Weil-McLain · Error codes
Weil-McLain error codes and alerts
Identical code numbers can mean different things on different controllers, so every entry is tied to the documented series, controller and manual version. A code is never a diagnosis.
If you smell gas
- Stop what you are doing. Do not use phones, switches, matches or anything that can spark inside.
- Go outside and leave the door open behind you.
- Call the FortisBC 24-hour emergency line at 1-800-663-9911 or dial 911.
Only after that, call ROMA about the boiler. Official guidance: FortisBC gas leaks and odour.
Weil-McLain ECO Tec Series 2 boilers and combis (display fault messages, manual 550-100-270)
control-not-receiving-24v-power
Control is not receiving 24V power. The control is not receiving 24V power, so nothing is shown on the display screen and the boiler will no…
Details
control-not-receiving-120v-power
Control is not receiving 120V power. The control is not receiving 120V power, so nothing is shown in the display screen and no other boiler …
Details
display-communication-lost
Communication lost between the control and the display. This condition occurs if communication is lost from the control to the display, so n…
Details
TEMP RISE TOO QUICKLY
Supply water temperature rises too quickly during the first two minutes the burner is on. This fault occurs if the supply water temperature …
Details
Communication errors
Display or main control communications out for 30 seconds. Communication errors occur if the display or main control communications are out …
Details
Control fault
Micro-controllers on the main board have a RAM or ROM error. A control fault occurs when the micro-controllers on the main board have a RAM …
Details
LOW WTR CUTOFF OPEN
Internal low water cutoff contacts open. This fault occurs if the internal low water cutoff contacts open, and a manual reset of the control…
Details
RETURN > SUPPLY
Return water temperature greater than the corresponding supply temperature by 10°F or more. This fault occurs if a return water temperature …
Details
Boiler Output sensor or Flue sensor
Dual temperature sensor values have spread by more than 10°F. This fault occurs if the dual temperature sensor values have spread by more th…
Details
FLUE TEMP TOO HIGH
Flue temperature sensor exceeds 210°F warning or 220°F lockout. This fault occurs if the flue temperature sensor exceeds 210°F, which is a w…
Details
LIMIT OPEN
Manual or automatic reset limit opens. This fault occurs if the manual or automatic reset limit opens, and an automatic external limit will …
Details
HIGH TEMP LIMIT
Boiler temperature sensor reached the High Temp Limit setting. This fault occurs when the boiler temperature sensor has reached the High Tem…
Details
FALSE FLAME
Flame detected when there should be no flame. This fault occurs if flame is detected when there should be no flame, so turn the boiler off a…
Lockout
GAS RELAY FAULT 1-4
Control detected a problem with the gas valve output circuit. This fault occurs when the control has detected a problem with the gas valve o…
Lockout
IGNITION 1 FAULT
Flame not detected or flame sense below minimum threshold after five ignition attempts. This fault occurs when the boiler went through five …
Lockout
IGNITION 2 FAULT
Running flame threshold not met after five ignition attempts. This fault occurs when the boiler went through five ignition attempts and did …
Lockout
FLAME LOSS FAULT
Flame value dropped below Proof of Ignition during stabilization. This fault occurs when the boiler went through five ignition attempts and …
Lockout
AIR PRESSURE Switch Open
Air pressure switch connection is open. This fault occurs when the air pressure switch connection is open, and it must be reset using the Ma…
Details
Closure Switch fault
Proof of Closure connections on J18 pins 2 and 3 are open. A Closure Switch fault occurs when the Proof of Closure connections on J18 pins 2…
Lockout
Configuration fault
Configuration data in the safety micro does not match the application micro. A configuration fault occurs when the configuration data in the…
Details
DHW Outlet > Boiler Out
DHW Outlet temperature greater than Boiler Outlet temperature on Combi models. This fault occurs on Combi models when the DHW Outlet tempera…
Details
Internal Clock Fault
Internal clock of the control is out of sync. This fault occurs when the internal clock of the control is out of sync, and it clears when th…
Details
Supply 60F > Return
Boiler Out temperature more than 60°F above Boiler In temperature. This fault occurs if either Boiler Out temperatures are greater than the …
Lockout
Flue 1 Sensor Open
Flue 1 sensor sensed open. The Flue 1 sensor is sensed as Open, and this fault clears automatically when the sensor is no longer sensed as O…
Details
Flue 1 Sensor Short
Flue 1 sensor sensed short. The Flue 1 sensor is sensed as Short, and this fault clears automatically when the sensor is no longer sensed as…
Details
Flue 2 Sensor Open
Flue 2 sensor sensed open. The Flue 2 sensor is sensed as Open, and this fault clears automatically when the sensor is no longer sensed as O…
Details
Flue 2 Sensor Short
Flue 2 sensor sensed short. The Flue 2 sensor is sensed as Short, and this fault clears automatically when the sensor is no longer sensed as…
Details
Boiler Out 1 Sensor Open
Boiler Out 1 sensor sensed open. The Boiler Out 1 sensor is sensed as Open, and this fault clears automatically when the sensor is no longer…
Details
Boiler Out 1 Sensor Short
Boiler Out 1 sensor sensed short. The Boiler Out 1 sensor is sensed as Short, and this fault clears automatically when the sensor is no long…
Details
Boiler Out 2 Sensor Open
Boiler Out 2 sensor sensed open. The Boiler Out 2 sensor is sensed as Open, and this fault clears automatically when the sensor is no longer…
Details
Boiler Out 2 Sensor Short
Boiler Out 2 sensor sensed short. The Boiler Out 2 sensor is sensed as Short, and this fault clears automatically when the sensor is no long…
Details
Boiler In Sensor Open
Boiler In sensor sensed open. The Boiler In sensor is sensed as Open, and this fault clears automatically when the sensor is no longer sense…
Details
Boiler In Sensor Short
Boiler In sensor sensed short. The Boiler In sensor is sensed as Short, and this fault clears automatically when the sensor is no longer sen…
Details
Blower Fault 1
Blower does not reach zero RPM within 4 minutes in Standby or Prepump mode. Blower Fault 1 occurs when the blower does not reach zero RPM wi…
Details
Blower Fault 2
Blower unable to reach required pre-purge or ignition speed or complete calibration. Blower Fault 2 occurs when the blower is unable to reac…
Lockout
Blower Fault 3
Blower outside of minimum or maximum speed for 10 seconds. Blower Fault 3 occurs when the blower is outside of the minimum or maximum speed …
Details
Wrong J6 Jumper
Voltage configuration jumper on J6 installed incorrectly. This fault occurs when the voltage configuration jumper on J6 is installed incorre…
Details
Hardware A2D Fault
Analog reading of the internal voltage reference on U1 read out of range twice in a row. This fault occurs when the analog reading of the in…
Details
Flame Circuit Fault
Digital flame input does not sense the circuit to have discharged appropriately. This fault occurs when the digital flame input does not sen…
Details
Supply Sensor
Boiler In sensor open or short while Supply Sensor is the target modulation sensor. This warning occurs when Supply Sensor is chosen as the …
Details
Return Sensor
Boiler Out sensor open or short while Return Sensor is the target modulation sensor. This warning occurs when Return Sensor is chosen as the…
Details
DHW Outlet Sensor
DHW Outlet sensor reads invalid on Combi models. On Combi models, this warning occurs when the DHW Outlet sensor reads invalid, and it clear…
Details
Outdoor Sensor Error
Outdoor temperature sensor short or open. This warning occurs when the outdoor temperature sensor is short or open, and it will automaticall…
Details
Exceeded Flow Rate
Combi block flow rate above the Maximum Flow Rate for the boiler model. On Combi models, this warning occurs when the Combi block has a flow…
Details
Target Reduced - Flue
Flue temperature between 200°F and 210°F reduces target temperature. This warning occurs when the flue temperature is detected between 200°F…
Details
Target Reduced - Boiler
Boiler Outlet sensor detected above Max Boiler Temp minus Boiler Out On Diff. This warning occurs when the Boiler Outlet sensor is detected …
Details
Target Reduced - Flow
Boiler Outlet sensor detected more than 50°F above the Boiler Inlet sensor. This warning occurs when the Boiler Outlet sensor is detected gr…
Details
Clock Fault
Real time clock chip is unable to be read. This warning occurs when the real time clock chip is unable to be read, and it clears when the re…
Details
Software Incompatible
Main control and display software are not compatible. This warning occurs when the main control and display software are not compatible, and…
Details
Virtual Input Active
Modbus is activating a virtual TT input. This warning occurs if Modbus is activating any virtual TT input, and it clears when no virtual inp…
Details
Unconfigured Net 1 or Net 2 Demand
Net 1 or Net 2 input active when its priority settings are not configured. This warning occurs when a Net 1 or Net 2 input is active while i…
Details
Weil-McLain Evergreen boilers (display fault messages; fault set identical in manuals 550-100-210 and 550-100-211)
Nothing shown on display screen and boiler will not respond to call for heat
Control is not receiving 24V power. The control is not receiving 24V power, so nothing appears on the display and the boiler will not respon…
Details
Nothing is shown in display screen and no other boiler components are operating
Control is not receiving 120V power. The control is not receiving 120V power, so nothing is shown on the display screen and no other boiler …
Details
Nothing is shown on display screen, but boiler is operating
Communication lost between control and display or display contrast misadjusted. Nothing is shown on the display screen while the boiler oper…
Details
TEMP RISE TOO QUICKLY
Supply water temperature rises too quickly during the first two minutes the burner is on. This fault occurs if supply water temperature in t…
Details
DISPLAY COMM Fault
Display communications out for 30 seconds. This fault occurs if display communications are out for 30 seconds, and it automatically resets w…
Details
Hardware Fault
Micro-controllers on main board have RAM or ROM error or communication is cut off. This fault occurs when the micro-controllers on the main …
Details
LOW WTR CUTOFF OPEN
Internal low water cutoff contacts open. This fault occurs if the internal low water cutoff contacts open, requiring manual reset of the con…
Details
SUPPLY 58° F > RETURN
Boiler Out temperature exceeded Boiler In temperature by more than 58° F. The Boiler Out temperature has exceeded the Boiler In temperature …
Details
RETURN > SUPPLY
Return water temperature greater than supply temperature by 10° F or more. This fault occurs if a return water temperature is greater than t…
Details
SUPPLY WATER TEMPERATURE TOO HIGH
System Supply temperature above 200° F while burner is running. This fault occurs when the System Supply temperature goes above 200º F while…
Details
TEMPERATURE SENSOR FAULT
Temperature sensor shorted or disconnected, or dual sensors spread by more than 10° F. This fault occurs if a temperature sensor has electri…
Details
FLUE TEMP TOO HIGH
Flue temperature sensor exceeds 210° F warning or 220° F lockout. This fault occurs if the flue temperature sensor exceeds 210º F as a warni…
Details
LIMIT OPEN
Manual or automatic reset limit opened. This fault occurs if a manual or automatic reset limit opens, and the external limit will reset auto…
Details
HIGH TEMP LIMIT
Boiler temperature sensor reached High Temp Limit setting. The boiler temperature sensor has reached the High Temp Limit setting, which is s…
Details
FLAME FAULT
Flame detected when there should be no flame. This fault occurs if flame is detected when there should be no flame, and it must be reset usi…
Lockout
GAS VALVE FAULT
Control detected a problem with the gas valve output circuit. The control has detected a problem with the gas valve output circuit, and it w…
Lockout
BLOWER FAULT
Blower unable to reach required speed or does not reach 0 RPM when turned off. The blower is unable to reach the required speed, or it does …
Details
IGNITION FAULT
Flame not detected after five ignition attempts. The boiler went through 5 ignition attempts and never detected flame, or the flame sense va…
Lockout
OUTDOOR SENSOR ERROR
Outdoor temperature sensor short or open (warning only). The outdoor temperature sensor is short or open, and this warning only fault will a…
Details
AIR PRESSURE Switch Open
Air Pressure switch connection open. This fault occurs when the Air Pressure switch connection is open, which can be caused by high pressure…
Details
Closure Switch fault
Proof of Closure connections on P7 Pins 2 and 3 open. The Proof of Closure connections on P7 Pins 2 and 3 are open, and each consecutive fai…
Lockout
Weil-McLain Ultra Series 4 boilers (display fault messages, manual 550-100-440)
TEMP RISE TOO QUICKLY
Temp Rise Too Quickly. Occurs when supply water temperature in the heat exchanger rises faster than 2 degrees F per second during the first …
Details
SUPPLY 58F > RETURN
Supply 58F > Return. Occurs when the boiler out temperature has exceeded the boiler in temperature by more than 58 degrees F while the burne…
Details
RETURN > SUPPLY
Return > Supply. Occurs when a return water temperature is greater than the corresponding supply temperature by 10 degrees F or more. The ta…
Details
TEMPERATURE SENSOR
Temperature Sensor. Occurs when a temperature sensor has electrically shorted (SHORT) or has become disconnected (OPEN). The table classifie…
Details
FLUE TEMP TOO HIGH
Flue Temp Too High. Occurs when the flue temperature sensor exceeds 216 degrees F. The table classifies it as auto reset, manual reset.…
Details
TEMPERATURE SENSOR
Temperature Sensor. Occurs when dual temperature sensor values have spread by more than 10 degrees F. The table classifies it as auto reset.…
Details
LOW WTR CUTOFF OPEN
Low Water Cutoff Open. Occurs when the Low Water Cutoff Device contacts open for more than 1 second. The table classifies it as manual reset…
Details
DISPLAY COMM
Display Comm. Occurs when display communications are out for 30 seconds. The table classifies it as auto reset.…
Details
LIMIT OPEN
Limit Open. Occurs when a manual or automatic reset limit opens. The table classifies it as auto reset, manual reset.…
Details
HIGH TEMP LIMIT
High Temp Limit. Occurs when the boiler temperature sensor reaches the High Temp Limit setting, which is no higher than 200 degrees F. The t…
Details
FLAME FAULT
Flame Fault. Occurs when flame is detected when there should be no flame. The table classifies it as manual reset.…
Lockout
BLOWER FAULT
Blower Fault. Occurs when the blower is unable to reach the required speed or does not reach 0 RPM when turned off. The table classifies it …
Details
IGNITION FAULT
Ignition Fault. Occurs when the boiler went through 5 ignition attempts and never detected flame. The table classifies it as auto reset, man…
Lockout
GAS VALVE FAULT
Gas Valve Fault. Occurs when the U-Control has detected a problem with its gas valve output circuit. The table classifies it as auto reset, …
Details
AIR PRESSURE SW FAULT
Air Pressure Switch Fault. Occurs when the air pressure switch is open, though residential Ultra boilers use a wire jumper between P7 pins 4…
Details
GAS PRESSURE SW FAULT
Gas Pressure Switch Fault. Occurs when the gas pressure switch is open, high or low, though residential Ultra Boilers do not use gas pressur…
Details
HW FAULT EXPANSION BRD
HW Fault Expansion Board. Occurs when the Expansion Control Board hardware has failed. The table classifies it as manual reset.…
Details
GV FAULT EXPANSION BRD
GV Fault Expansion Board. Occurs when the gas valve output of the Expansion Board has failed. The table classifies it as manual reset.…
Details
EXP BOARD COM FAULT
Exp Board Com Fault. Occurs when communication between the Expansion Control Board and the U-Control Board has failed. The table classifies …
Details
Weil-McLain GV90+ Series 2 (POWER LED flash-code diagnostics, manual 550-143-010)
POWER LED flashes once per second
Reversed 120 VAC connection or insufficient earth ground. This flash pattern means the 120 VAC connection to the boiler is reversed or the e…
Details
POWER LED 2 flashes
Internal fault, microprocessor or memory. Flash code 2 indicates an internal fault involving the microprocessor or the memory of the control…
Lockout
POWER LED 3 flashes
Low water cutoff (LWCO) circuit fault. Flash code 3 indicates a fault condition in the low water cutoff circuit of the boiler. The table cla…
Lockout
POWER LED 4 flashes
Unused flash code. Flash code 4 is printed as unused, meaning it is not assigned to any fault condition.…
Details
POWER LED 5 flashes
Internal fault, water thermistors disagree. Flash code 5 indicates an internal fault exists because the water thermistors disagree with each…
Lockout
POWER LED 6 flashes
Internal fault, gas valve circuit. Flash code 6 indicates an internal fault has been detected in the gas valve circuit of the boiler. The ta…
Lockout
POWER light flashing alone
Reversed polarity of 120 VAC power wires. POWER light flashing alone usually indicates reversed polarity of the 120 VAC power wires to the b…
Details
POWER and TSTAT/CIRC lights flashing
Stray voltage on thermostat wires or return water below 130° F. Flashes on the POWER and TSTAT/CIRC lights together usually mean stray volta…
Details
POWER and PRESS SWITCH lights flashing
Pressure switch closed unexpectedly or failed to close in time. Flashes on the POWER and PRESS SWITCH lights mean the pressure switch is clo…
Details
POWER and FLAME lights flashing
Flame sensed out of sequence or three failed ignition attempts. Flashes on the POWER and FLAME lights mean flame was sensed without a call f…
Lockout
FLAME lights flashing
Flame loss or flame not sensed during ignition trial. FLAME lights flashing indicates flame loss, or flame not sensed during the trial for i…
Lockout
Solid LWCO light
Low water condition occurred. A solid LWCO light indicates that a low water condition has occurred in the boiler.…
Details
LWCO light flashing alone
LWCO requires maintenance. The LWCO light flashing alone with three rapid pulses indicates that the LWCO requires maintenance.…
Details
TSTAT/CIRC light flashing alone
Return water below 40° F with continuous circulator run. TSTAT/CIRC light flashing alone usually indicates the return water temperature sens…
Details
LIMIT light flashing alone
Open or shorted return water or supply temperature or LWCO sensor. LIMIT light flashing alone usually indicates an open or shorted return wa…
Details
POWER and LIMIT lights flashing
Over-temperature lockout. Flashes on the POWER and LIMIT lights together indicate an over-temperature lockout, and the control will only res…
Lockout
Weil-McLain Simplicity (display fault messages and warnings, manual 550-143-073)
Nothing shown on display screen and boiler will not respond to call for heat
Control is not receiving 24V power. The control is not receiving 24V power, so nothing is shown on the display screen and the boiler will no…
Details
Nothing is shown in display screen and no other boiler components are operating
Control is not receiving 120V power. The control is not receiving 120V power, so nothing is shown in the display screen and no other boiler …
Details
Nothing is shown on display screen, but boiler is operating
Communication lost between control and display. Communication from the control to the display has been lost, so nothing is shown on the disp…
Details
TEMP RISE
Supply water temperature rises too fast during burner startup. Supply water temperature in the heat exchanger rose faster than 20° F over 2 …
Details
COMM ERR
Display or main control communication error. Display or main control communications have been out for 30 seconds, and the fault resets autom…
Details
CTRL FAULT
Micro-controllers on main board have RAM or ROM error. Micro-controllers on the main board have a RAM or ROM error, which causes a control f…
Details
LWCO OPEN
Internal low water cutoff contacts open. The internal low water cutoff contacts have opened, and the control requires a manual reset while t…
Details
RETURN > SUPPLY or BLR IN > BLR OUT
Return water temperature greater than corresponding supply temperature. A return water temperature is greater than the corresponding supply …
Details
BOILER OUT SNSR or FLUE SENSOR
Dual temperature sensors have spread by more than 10° F. The dual temperature sensors have values that have spread by more than 10° F, which…
Details
FLUE TOO HIGH
Flue temperature sensor exceeds limit. The flue temperature sensor exceeded 210° F, which is a warning, or 220° F, which is a lockout condit…
Details
MANUAL LIMIT or AUTO LIMIT
Manual or automatic reset limit opened. The manual or automatic reset limit has opened, and an automatic external limit will reset 2½ minute…
Details
HIGH TEMP LIMIT
Boiler temperature sensor reached High Temp Limit setting. The boiler temperature sensor reached the High Temp Limit setting of the boiler. …
Details
FALSE FLAME
Flame detected when there should be no flame. Flame was detected when there should have been no flame present in the boiler. The table class…
Lockout
GAS RELAY 1-4
Control detected a problem with gas valve output circuit. The control has detected a problem with the gas valve output circuit and will perf…
Lockout
IGN FAULT 1
Flame not detected after five ignition attempts. The boiler went through 5 ignition attempts and never detected flame, or the flame sense va…
Lockout
IGN FAULT 2
Running flame threshold not met after five ignition attempts. The boiler went through 5 ignition attempts but did not meet the running flame…
Lockout
FLAME LOSS
Flame value dropped below Proof of Ignition during stabilization. The boiler went through 5 ignition attempts and the flame value dropped be…
Lockout
AIR P-SW OPEN
Air Pressure switch connection open. The Air Pressure switch connection is open, which can be caused by high pressure in the exhaust pipe or…
Details
CLOSURE SWITCH
Proof of Closure connections on J18 Pins 2 and 3 open. The Proof of Closure connections on J18 Pins 2 and 3 are open, which leads to repeate…
Lockout
CONFIG FAULT
Configuration data mismatch between safety micro and application micro. Configuration data in the control safety micro does not match the co…
Details
DHW OUT > BLR OUT
DHW Outlet temperature greater than Boiler Outlet temperature. The DHW Outlet temperature is greater than the Boiler Outlet temperature plus…
Details
CHIP FAULT
Internal clock of the control is out of sync. The internal clock of the control is out of sync, and this fault clears when the control sees …
Details
60F > RETURN
Boiler Out temperature more than 60° F above Boiler In temperature. Boiler Out temperatures were greater than the Boiler In temperature by m…
Lockout
FLUE 1 OPEN
Flue 1 sensor sensed open. The FLUE 1 sensor is sensed as Open, and the fault clears automatically when the sensor is no longer open or shor…
Details
FLUE 1 SHORT
Flue 1 sensor sensed short. The FLUE 1 sensor is sensed as Short, and the fault clears automatically when the sensor is no longer open or sh…
Details
FLUE 2 OPEN
Flue 2 sensor sensed open. The FLUE 2 sensor is sensed as Open, and the fault clears automatically when the sensor is no longer open or shor…
Details
FLUE 2 SHORT
Flue 2 sensor sensed short. The FLUE 2 sensor is sensed as Short, and the fault clears automatically when the sensor is no longer open or sh…
Details
BOILER OUT1 OPEN
Boiler Out 1 sensor sensed open. The BOILER OUT1 sensor is sensed as Open, and the fault clears automatically when the sensor is no longer o…
Details
BOILER OUT1 SHRT
Boiler Out 1 sensor sensed short. The BOILER OUT1 sensor is sensed as Short, and the fault clears automatically when the sensor is no longer…
Details
BOILER OUT2 OPEN
Boiler Out 2 sensor sensed open. The BOILER OUT2 sensor is sensed as Open, and the fault clears automatically when the sensor is no longer o…
Details
BOILER OUT2 SHRT
Boiler Out 2 sensor sensed short. The BOILER OUT2 sensor is sensed as Short, and the fault clears automatically when the sensor is no longer…
Details
BOILER IN OPEN
Boiler In sensor sensed open. The BOILER IN sensor is sensed as Open, and the fault clears automatically when the sensor is no longer open o…
Details
BOILER IN SHORT
Boiler In sensor sensed short. The BOILER IN sensor is sensed as Short, and the fault clears automatically when the sensor is no longer open…
Details
BLOWER FAULT 1
Blower does not reach zero RPM in Standby or Prepump mode. The blower does not reach zero RPM within 4 minutes when the mode is Standby or P…
Details
BLOWER FAULT 2
Blower unable to reach required speed or complete calibration. The blower is unable to reach the required pre-purge speed or ignition speed,…
Lockout
BLOWER FAULT 3
Blower outside of minimum or maximum speed while burner firing. The blower is outside of the minimum or maximum speed for 10 seconds while t…
Details
BLOWER FAULT 4
Blower drops to zero RPM while burner firing. The blower drops to zero RPM while the burner is firing, which triggers this fault condition. …
Details
WRONG J6
Voltage configuration jumper on J6 installed incorrectly. The voltage configuration jumper on J6 is installed incorrectly, such as a 24VAC j…
Details
A2D FAULT
Internal voltage reference analog reading out of range. The analog reading of the internal voltage reference on U1 was read out of range 2 t…
Details
FLAME CIRCUIT
Digital flame input does not sense circuit discharge. The digital flame input does not sense the circuit to have discharged appropriately, w…
Details
SUPPLY SENSOR
Boiler In sensor open or short while Supply Sensor is the modulation sensor. When Supply Sensor is chosen as the Target Modulation sensor, a…
Details
RETURN SENSOR
Boiler Out sensor open or short while Return Sensor is the modulation sensor. When Return Sensor is chosen as the Target Modulation sensor, …
Details
DHW OUT SNSR
DHW Outlet sensor read invalid. The DHW Outlet sensor read invalid, and the warning clears when the DHW Outlet sensors both read as valid. T…
Details
OUTDOOR SENSOR
Outdoor temperature sensor short or open. The outdoor temperature sensor is short or OPEN, and this warning will automatically reset if the …
Details
EXCEEDED FLOW RATE
Combi block flow rate above Maximum Flow Rate. On Combi models, the Combi block has a flow rate above the Maximum Flow Rate for the boiler m…
Details
REDUCED TGT - FLUE
Flue temperature between 200° F and 210° F reduces target temperature. Flue temperature was detected between 200°F and 210°F, so the control…
Details
REDUCED TGT - BLR
Boiler Outlet sensor above Max Boiler Temp minus Boiler Out On Diff. The Boiler Outlet sensor is detected above Max Boiler Temp minus Boiler…
Details
REDUCED TGT - FLOW
Boiler Outlet sensor more than 50° F above Boiler Inlet sensor. The Boiler Outlet sensor is detected greater than the Boiler Inlet sensor pl…
Details
CLOCK FAULT
Real time clock chip unable to be read. The real time clock chip is unable to be read, which causes this warning to be displayed. The table …
Details
WRONG SOFTWARE
Main control and display software not compatible. The main control and display software are not compatible, which causes this warning to be …
Details
LOW FLAME SHUTDOWN
Flame quality drops below desired running value. This warning occurs if flame quality drops below the desired running value, and it clears w…
Details
INTL DISPL COMM ERR
Display loses communication with its radio. The display has lost communication with its radio, and this warning clears after the display suc…
Details
PREHEAT ACTIVE
Boiler is running the PREHEAT function. This message occurs when the boiler is running the PREHEAT function, and it clears when PREHEAT is n…
Details
CALIBRATE NEEDED
Blower motor has not yet undergone calibration. The boiler blower motor has not yet undergone calibration, which triggers this message. The …
Details
CALIBRATE IS ACTIVE
Blower calibration is underway. Blower calibration is underway, and this message clears when calibration is successfully completed or anothe…
Details
Weil-McLain AquaBalance Series 2 (A## hard lockouts and F## soft lockouts, manual 550-100-325)
A01
No burner ignition after five attempts. After five failed ignition attempts the boiler goes into lockout and manual reset is required to ret…
Lockout
A02
False flame indication. The control sees a flame present signal while the burner is off, indicating an electrode, ignition cable, or wiring …
Lockout
A03
High limit protection: pump does not run or no water circulation. High limit protection activates when the pump does not run or there is no …
Details
A04
F07 repeated 3 times in the last 24 hours. The exhaust duct safety device activates when fault F07 has been generated three times in the las…
Details
A05
No frequency feedback from fan after 1 hour. Fan protection is activated when fault F15 has occurred continuously for one hour without frequ…
Details
A06
6 times flame loss in 4 minutes time frame. The boiler locks out after the flame is lost six times within a four minute time frame and manua…
Lockout
A16
Outside sensor is not connected. This error means the outdoor temperature sensor is not connected to the boiler control. The table classifie…
Details
A23
Nominal water pressure not reached within maximum allowed time. The boiler locks out because the nominal water pressure was not reached with…
Details
A26
F40 repeated 3 times in the last hour. This system installation fault is generated when the F40 error has been repeated three times in one h…
Details
A41
Temperature sensor not or bad connected to the pipe (CH mode). The supply sensor is disconnected from the pipe or badly positioned so the CH…
Details
A42
Too high difference between two CH supply water temperature sensors. A too high temperature difference between the two CH supply water tempe…
Details
A44
Temperature sensor not or bad connected to the pipe (DHW mode). The temperature sensor is not connected or is badly connected to the pipe in…
Details
A61
Flame circuit error. A controller ABM08A internal error is detected in the flame circuit, requiring ground connection checks and possible co…
Details
A62
Gas valve circuit. There is no communication between the controller and the gas valve because the controller is not connected or the valve i…
Details
A63
E2 prom error. The E2 prom error is a controller ABM08A fault that may require checking the ground connection and replacing the controller. …
Details
A65
ADC circuit error. The ADC circuit error is a controller ABM08A internal error that may require ground checks and controller replacement. Th…
Details
F07
Exhaust gases temperature is too high. The controller stops the boiler when exhaust gas temperature stays too high for more than 5 seconds, …
Details
F10
CH supply water temperature sensor 1 error. The CH supply sensor 1 is out of normal operating range due to short circuit or open circuit, di…
Details
F11
CH return water temperature sensor error. The CH return sensor is out of normal operating range due to a short circuit or open circuit, disa…
Details
F12
DHW water temperature sensor error. The DHW sensor is out of normal operating range, and in error mode only the DHW heat demands will be dis…
Details
F13
Exhaust gases temperature sensor error. The exhaust sensor is out of normal operating range due to short circuit or open circuit, disabling …
Details
F14
CH supply water temperature sensor 2 error. The CH supply sensor 2 or high limit sensor is out of normal operating range, disabling heat dem…
Details
F15
Minimum and maximum frequency feedback from fan error. If the controller measures fan frequency lower than 20Hz or higher than 295Hz, the er…
Details
F20
Water pressure in the CH installation is near the low level. The water pressure measured by the sensor is above the low level but below nomi…
Details
F21
Water pressure in the CH installation is near the high level. The water pressure is near the high level, producing a warning with linear out…
Details
F27
Exhaust gas temperature is too high (PVC/CPVC/Polypro/AL29-4C selection). If flue gas temperature stays above the vent material maximum duri…
Details
F34
Low mains voltage. Low voltage below 100VAC triggers this indication, which is resolved when the voltage supply returns above 100VAC. The ta…
Details
F35
Frequency error. The controller measures a voltage supply frequency different from the supply frequency parameter, and the error resolves wh…
Details
F37
Water pressure in the CH installation is too low. Low water pressure in the central heating system switches off the heat demand and the pump…
Details
F39
Outside sensor error. The outside sensor is out of normal operating range from -22°F to +158°F, and the error resolves when the sensor retur…
Details
F40
Water pressure in the CH installation is too high or there's a Control fault. High water pressure above the high level switches off the heat…
Details
F43
Heat exchanger protection. A fault is generated due to lack of system water when the slope temperature rises beyond the heat exchanger prote…
Details
F47
Water pressure sensor not connected. The water pressure sensor is not connected, so heat demand and pumps are switched off until the sensor …
Details
F50
Variable input switch contact opened. The boiler reports that the variable input switch contact has opened, and the manual refers to the var…
Details
F51
Low water error. The low water cutoff sensor is open, an indication that occurs only when the variable input switch functionality parameter …
Details
F52
Too high difference between two CH supply water temperature sensors. Error 52 is created when the difference between the two CH supply senso…
Details
F53
High limit thermostat input error. When the high limit thermostat is open and variable input functionality is set to 4, the boiler is forced…
Details
F64
5 MicroCom reset in 15 minutes time frame. Five MicroCom resets within a 15 minute time frame stop the boiler, and main power must be remove…
Details
F66
Software doesn't match. The software mismatch stops the boiler, and the device must be reprogrammed or replaced to restore normal operation …
Details
Weil-McLain CGa Series 4 cast-iron boilers (display fault messages, manual 550-100-223)
CONFIRM CONFIGURATION
Board not configured. The board is not configured, so the configuration number shown must be confirmed to match the boiler model before oper…
Details
CONFIG MISMATCH
Configuration number stored in board does not match the configuration number the control reads from the harness. The configuration number st…
Details
AUTO LIMIT OPEN
Auto Limit chain electrical circuit is open. The Auto Limit chain electrical circuit is open, so the jumper, factory wiring, and connected l…
Details
MANUAL LIMIT OPEN
Manual Limit chain electrical circuit is open. The Manual Limit chain electrical circuit is open, so the jumper, factory wiring, and connect…
Details
FALSE FLAME
Flame detected when the gas valve is not powered. Flame is detected by the control when the gas valve is not powered, indicating flame is pr…
Lockout
IGNITION FAULT
Maximum number of failed ignitions has been reached. The maximum number of failed ignitions has been reached, so pilot spark, gas presence, …
Lockout
FLAME LOST
Flame has been lost during operation. Flame has been lost during boiler operation, so the pilot flame sense wiring, flame rod, and gas press…
Lockout
BOILER OUT OPEN
Boiler Control measures an open circuit. The Boiler Control measures an open circuit in the Boiler Out sensor, so wiring should be checked f…
Details
BOILER OUT SHORT
Boiler Control measures a closed circuit with no resistance. The Boiler Control measures a closed circuit with no resistance, which indicate…
Details
HARDWARE FAULT 1
Control Board hardware faults including A/D converter, flame circuit, RAM, ROM, sequence, and RAM disagrees faults. Control Board hardware f…
Details
HARDWARE FAULT 2
Control Board K3 relay open fault. A K3 relay open fault on the control board has occurred, which may indicate a possible control board fail…
Details
HARDWARE FAULT 3
Control Board K3 relay closed fault. A K3 relay closed fault on the control board has occurred, which may indicate a possible control board …
Details
HARDWARE FAULT 4
Control Board K4 relay open fault. A K4 relay open fault on the control board has occurred, which may indicate a possible control board fail…
Details
HARDWARE FAULT 5
Possible control board failure or pilot valve harness short to 24 Vac. A possible control board failure or pilot valve harness short to 24 V…
Details
HARDWARE FAULT 6
Control Board K5 relay open fault. A K5 relay open fault on the control board has occurred, which may indicate a possible control board fail…
Details
HARDWARE FAULT 7
Possible control board failure or main valve harness short to 24 Vac. A possible control board failure or main gas valve harness short to 24…
Details
HARDWARE FAULT 8
Control Board K6 relay open fault. A K6 relay open fault on the control board has occurred, which may indicate a possible control board fail…
Details
CH VOLTAGE HIGH
CH / Thermostat1 input excessive voltage. The CH/Thermostat1 input has excessive voltage, so the supply voltage must be measured between con…
Details
DHW VOLTAGE HIGH
DHW / Thermostat2 input excessive voltage. The DHW/Thermostat2 input has excessive voltage, so the supply voltage must be measured between c…
Details
SPILL SWITCH
Burner spill caused by possible vent blockage or wind. Burner spill caused by a possible vent blockage or wind triggers the spill switch, wh…
Details
Weil-McLain CGi Series 5 cast-iron boilers (display fault messages, manual 550-100-629)
CONFIRM CONFIGURATION
Board not configured. The board is not configured, so the configuration number shown must be confirmed to match the CGi boiler model configu…
Details
CONFIG MISMATCH
Configuration number stored in board does not match the configuration number the control reads from the harness. The configuration number st…
Details
AUTO LIMIT OPEN
Auto Limit chain electrical circuit is open. The Auto Limit chain electrical circuit is open, so the jumper, factory wiring, and connected l…
Details
MANUAL LIMIT OPEN
Manual Limit chain electrical circuit is open. The Manual Limit chain electrical circuit is open, so the jumper, factory wiring, and connect…
Details
FALSE FLAME
Flame detected when the gas valve is not powered. Flame is detected by the control when the gas valve is not powered, indicating flame is pr…
Lockout
IGNITION FAULT
Maximum number of failed ignitions has been reached. The maximum number of failed ignitions has been reached, so pilot spark, gas presence, …
Lockout
FLAME LOST
Flame has been lost during operation. Flame has been lost during boiler operation, so the pilot flame sense wiring, flame rod, and gas press…
Lockout
BOILER OUT OPEN
Boiler Control measures an open circuit. The Boiler Control measures an open circuit in the Boiler Out sensor, so wiring should be checked f…
Details
BOILER OUT SHORT
Boiler Control measures a closed circuit with no resistance. The Boiler Control measures a closed circuit with no resistance, which indicate…
Details
HARDWARE FAULT 1
Control Board hardware faults including A/D converter, flame circuit, RAM, ROM, sequence, and RAM disagrees faults. Control Board hardware f…
Details
HARDWARE FAULT 2
Control Board internal relay error. A control board internal relay error has occurred, which may indicate a possible control board failure.…
Details
HARDWARE FAULTS 3, 4, 6, 8
Control Board internal relay error. Control board internal relay errors for hardware faults 3, 4, 6, and 8 may indicate a possible control b…
Details
HARDWARE FAULT 5
Possible control board failure or pilot valve harness short to 24 Vac. A possible control board failure or pilot valve harness short to 24 V…
Details
HARDWARE FAULT 7
Possible control board failure or main valve harness short to 24 Vac. A possible control board failure or main gas valve harness short to 24…
Details
CH VOLTAGE HIGH
CH / Thermostat1 input excessive voltage. The CH/Thermostat1 input has excessive voltage, so the supply voltage must be measured between con…
Details
DHW VOLTAGE HIGH
DHW / Thermostat2 input excessive voltage. The DHW/Thermostat2 input has excessive voltage, so the supply voltage must be measured between c…
Details
PS FAULT
Pressure switch fault. A pressure switch fault requires checking the pressure switch wires and verifying the switch operation during an igni…
Lockout
Weil-McLain EG Series cast-iron boilers (display faults, manual 550-100-225)
CONFIRM CONFIGURATION
Board not configured. Does the configuration number displayed match the boiler model? EG Water with Tankless = Configuration # 14; EG Water …
Details
CONFIG MISMATCH
Configuration number stored in the board does not match the configuration number the control reads from the harness. Is the configuration nu…
Details
AUTO LIMIT
Auto Limit chain / electrical circuit is open. Is the Factory Jumper installed in the Auto Limit terminal block? Verify continuity of the Au…
Details
MANUAL LIMIT
Manual Limit chain / electrical circuit is open. Is the Factory Jumper installed in the Manual Limit terminal block? Verify continuity of th…
Details
FALSE FLAME
Flame detected when the gas valve is not powered. Verify flame is present at Pilot or Main Burners. If yes, close manual ball gas valves and…
Lockout
IGNITION FAULT
Maximum number of failed ignitions has been reached. Is the Pilot sparking? If not, verify wiring from control to pilot assembly; remove spa…
Lockout
FLAME LOST
Flame has been lost during operation. Check Pilot Flame Signal in the Control Diagnostics: a flame signal < 60 is required for proven flame.…
Lockout
BOILER OUT OPEN
Boiler Control measures an open circuit. Inspect Boiler Out Sensor and wiring. Measure the individual resistance values of Boiler Out and co…
Details
BOILER OUT SHORT
Boiler Control measures a closed circuit with no resistance. Inspect Boiler Out Sensor and wiring. Measure the individual resistance values …
Details
HARDWARE FAULT 1
Control Board Hardware faults - A/D converter fault, flame circuit fault, RAM fault, ROM fault, sequence fault, RAM disagrees fault. Possibl…
Details
HARDWARE FAULT 2
Control Board K3 Relay Open Fault. Possible Control Board failure. Cycle power on control. If fault reoccurs when transitioning from Steady …
Details
HARDWARE FAULT 3
Control Board K3 Relay Closed Fault. Possible Control Board failure. Cycle power on control. If fault reoccurs when ending the next heat cyc…
Details
HARDWARE FAULT 4
Control Board K4 Relay Open Fault. Possible Control Board failure. Cycle power on control. If fault reoccurs when ending the next heat cycle…
Details
HARDWARE FAULT 5
Possible Control board failure or Pilot valve harness short to 24 Vac. Disconnect Pilot valve harness at control P12. Check for voltage on t…
Details
HARDWARE FAULT 6
Control Board K5 Relay Open Fault. Possible Control Board failure. Cycle power on control. If fault reoccurs when ending the next heat cycle…
Details
HARDWARE FAULT 7
Possible Control board failure or Main valve harness short to 24 Vac. Disconnect Main Gas valve harness at control P12. Check for voltage on…
Details
HARDWARE FAULT 8
Control Board K6 Relay Open Fault. Possible Control Board failure. Cycle power on control. If fault reoccurs when ending the next heat cycle…
Details
CH VOLTAGE HIGH
CH / Thermostat1 input excessive voltage. Unplug the control P3 connector. Measure the voltage between the control connector's Pins 1 & 3. I…
Details
DHW VOLTAGE HIGH
DHW / Thermostat2 input excessive voltage. Unplug the control P3 connector. Measure the voltage between the control connector's Pins 4 & 6. …
Details
SPILL SWITCH
Burner spill caused by possible vent blockage or wind. Check Spill Switch for continuity. Press reset button if open circuit detected. If th…
Details
POWER (flashes once per second)
120 VAC connection to boiler reversed. MAY remove 120VAC power for more than 2 seconds to clear lockout OR ignition control will automatical…
Lockout
Flash code 2
Internal fault, microprocessor or memory. POWER LED flashes 2 times rapidly followed by 2 seconds off, then repeats. MAY remove 120VAC power…
Lockout
Flash code 5
Internal fault, water thermistors disagree. POWER LED flashes 5 times rapidly followed by 2 seconds off, then repeats. MAY remove 120VAC pow…
Lockout
Flash code 6
Internal fault, gas valve circuit. POWER LED flashes 6 times rapidly followed by 2 seconds off, then repeats. MAY remove 120VAC power for mo…
Lockout
ALL LED'S FLASHING
Failure to establish pilot flame after 4 attempts. See Troubleshooting Charts 1 through 7 (control supplement pages 30-35). MAY remove 120VA…
Lockout
Solid LWCO LED
Low water condition occurred. Low water cutoff condition; check boiler water level and LWCO circuit. The table classifies it as hard lockout…
Lockout
POWER + TSTAT/CIRC
High voltage detected on TSTAT circuit. MAY remove 120VAC power for more than 2 seconds, cycle thermostat for between 2 and 20 seconds, OR i…
Lockout
POWER + DAMPER
Damper stuck closed or unable to close end switch within 45 seconds from TSTAT call. MAY remove 120VAC power for more than 2 seconds, cycle …
Lockout
POWER + FLAME
Flame sensed without call for heat or out of sequence during ignition trial. MAY remove 120VAC power for more than 2 seconds, cycle thermost…
Lockout
DAMPER
Damper end switch opened after it had been proven closed. Indicator-light caution summary. See Troubleshooting Charts 1 through 7 (control s…
Details
LIMIT
Fault detected in temperature sensing hardware. Indicator-light caution summary. See Troubleshooting Charts 1 through 7 (control supplement …
Details
FLAME
Flame loss or flame not sensed during trial for ignition. Indicator-light caution summary. See Troubleshooting Charts 1 through 7 (control s…
Lockout
LWCO
LWCO circuit approaching lockout state - sensor requires maintenance. LWCO LED will flash 3 times when maintenance is required. The table cl…
Details
Talk to a boiler technician
Describe what the boiler is doing and get a straight answer about the next step.
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