U.S. Boiler Company · Error codes
U.S. Boiler Company 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.
U.S. Boiler Alpine condensing boilers (Sage2.X control; soft and hard lockout codes, I&O 103448-12)
1
Anti Short Cycle. Minimum time between starts has not been reached, a normal delay used to avoid excessive cycles. The table classifies it a…
Lockout
2
Boiler Safety Limit Open. A boiler safety limit wired to terminals J6-1, 2 or 3 is open, so check the limit devices for loose wiring and the…
Lockout
3
Boiler Safety Limit (External) Open. The boiler safety limit or external limit wired to terminals J5-1 is open, so check for loose wiring or…
Lockout
4
Supply High Limit. The Sage2.X supply sensor detected water temperatures in excess of 210°F, typically from a heating load far below minimum…
Lockout
5
DHW High Limit. The Sage2.X DHW sensor detected temperatures in excess of the setpoint, typically from a DHW load far below the minimum firi…
Lockout
6
Stack High Limit. The Sage2.X flue gas stack sensor detected temperatures in excess of 204°F, so check whether the heat exchanger needs clea…
Lockout
7
Return Sensor Fault. The return temperature sensor is shorted or open, so check for shorted or mis-wired return sensor wiring and replace a …
Lockout
8
Supply Sensor Fault. The supply temperature sensor is shorted or open, so check for shorted or mis-wired supply sensor wiring and replace a …
Lockout
9
DHW Sensor Fault. The Domestic Hot Water temperature sensor is shorted or open, so check for shorted or mis-wired DHW sensor wiring and repl…
Lockout
10
Stack Sensor Fault. The flue gas stack temperature sensor is shorted or open, so check for shorted or mis-wired flue temperature sensor wiri…
Lockout
11
Ignition Failure. Models ALP080B through ALP285B suffered flame failure after 5 tries to restart, so check gas pressure, purge the gas line,…
Lockout
12
Flame Detected Out of Sequence. A flame signal was present when there should be no flame, so check the gas valve before replacing it and ver…
Lockout
13
Flame Rod Shorted to Ground. The flame rod is shorted to ground, so check for shorted or mis-wired flame rod wiring and replace a defective …
Lockout
14
ΔT Inlet/Outlet High. The temperature rise between supply and return is too high, so verify the circulator is operating and that circulator …
Lockout
15
Return Temp Higher than Supply. The return sensor temperature reads higher than the supply sensor for at least 75 seconds, so check flow dir…
Lockout
16
Supply Temp Risen Too Quickly. The supply water temperature has risen too quickly, so check for inadequate boiler water flow and verify the …
Lockout
17
Blower Speed Not Proved. The control is waiting for blower speed to match the purge and light-off set point, indicating a normal sequencing …
Lockout
18
Light-off Rate Proving Failed. The blower is not running at light-off rate when it should or its speed signal is not detected, so check the …
Lockout
19
Purge Rate Proving Failed. The blower is not running at purge rate when it should or its speed signal is not detected, so check the 120 VAC …
Lockout
20
Invalid Safety Parameters. An unacceptable Sage2.X control safety related parameter was detected, so check the parameter selection, reset th…
Lockout
21
Invalid Modulation Parameter. An unacceptable Sage2.X control modulation related parameter was detected, so reset the control to clear the l…
Lockout
22
Safety Data Verification Needed. A safety related parameter change was detected and a verification has not been completed, so verify the cha…
Lockout
23
24VAC Voltage Low/High. The Sage2.X control 24 VAC power is high or low, so check the 24 VAC power wiring, harness, and transformer for loos…
Lockout
24
Fuel Valve Error. Power was detected at the fuel valve output when the fuel valve should be off, so check the gas valve harness connections …
Lockout
25
Hardware Fault. An internal control failure was detected, so reset the control and replace the Sage control if the problem reoccurs. The tab…
Lockout
26
Internal Fault. An internal control failure was detected, so reset the control and replace the Sage control if the problem reoccurs. The tab…
Lockout
27
Unknown Fault. An unknown fault was detected by the control, so reset the control and replace the Sage control if the problem reoccurs. The …
Lockout
ER0011
Adjustment Mode Password Timeout. The control and display are not defective but the password timed out, so cycle power to the display to res…
Details
ER0012
Control Failed. A control failure was detected by the display, so replace the defective Sage control. The table classifies it as Display Fau…
Details
U.S. Boiler K2 watertube condensing boilers (soft and hard lockout codes, I&O 107672-03)
2
Boiler Safety Limit Open. The boiler safety limit wired to terminals J6-1 or 3 is open; listed causes are an external limit with water tempe…
Lockout
3
Boiler Safety Limit Open. The boiler safety limit wired to terminal J5-1 (blocked flue/inlet switch) is open; before a call for heat the air…
Lockout
4
Supply High Limit. The control supply sensor detected temperatures in excess of 210°F; listed causes are a heating load far below the minimu…
Lockout
6
Stack High Limit. The control flue gas (stack) sensor detected temperatures in excess of 214°F (101°C); listed causes are a heat exchanger t…
Lockout
7
Return sensor (10 KOhms) fault. The return temperature sensor is shorted or open; listed causes are shorted or mis-wired return sensor wirin…
Lockout
8
Supply sensor (10 KOhms) fault. The supply temperature sensor is shorted or open; listed causes are shorted or mis-wired supply sensor wirin…
Lockout
10
Stack sensor (10 KOhms) fault. The flue gas (stack) temperature sensor is shorted or open; listed causes are shorted or mis-wired flue tempe…
Lockout
11
Ignition failure. Flame failure after 5 tries to restart with the flame rod not detecting flame; listed causes include no gas pressure, gas …
Lockout
12
Flame detected out of sequence. A flame signal was present when there should be no flame; the listed cause is a defective gas valve, so make…
Lockout
13
Flame rod shorted to ground. The flame rod is shorted to ground; listed causes are shorted or mis-wired flame rod wiring, a defective flame …
Lockout
14
Differential Temperature inlet/outlet high. The temperature rise between supply and return is too high; listed causes are inadequate boiler …
Lockout
15
Return temp higher than supply. The control reads a return sensor temperature higher than the supply sensor temperature for at least 75 seco…
Lockout
16
Supply temp has risen too quickly. The supply water temperature has risen too quickly; the listed cause is inadequate boiler water flow, so …
Lockout
17
Normal waiting for blower speed to match purge and light-off setpoint. The control is waiting for blower speed to match the purge and light-…
Lockout
18
Light off rate proving failed. The blower is not running at light-off rate when it should or its speed signal is not detected; listed causes…
Lockout
19
Purge rate proving failed. The blower is not running at purge rate when it should or its speed signal is not detected; listed causes are a l…
Lockout
20
Invalid Safety Parameters. An unacceptable control safety related parameter was detected; safety parameter verification is required and the …
Lockout
21
Invalid Modulation Parameter. An unacceptable control modulation related parameter was detected; reset the control to clear the lockout. The…
Lockout
22
Safety data verification needed. A safety related parameter change was detected and verification has not been performed. The table classifie…
Lockout
23
24VAC Voltage low/high. The control 24 VAC power is high or low; listed causes are loose 24 VAC power wiring or harness, miswired harness ca…
Lockout
24
Fuel Valve Error. Power was detected at the fuel valve output when the fuel valve should be off; reset the control and replace it if the pro…
Lockout
25
Hardware Fault. An internal control failure was detected; reset the control and replace it if the problem reoccurs. The table classifies it …
Lockout
26
Internal Fault. An internal control failure was detected; reset the control and replace it if the problem reoccurs. The table classifies it …
Lockout
27
Undefined Fault. An undefined fault was detected; consult the factory. The table classifies it as Soft Lockout.…
Lockout
27
Undefined Fault. An undefined fault was detected; reset the control and replace it if the problem reoccurs. The table classifies it as Hard …
Lockout
28 or 53
Air Proving Switch Failed to Close. The air proving switch failed to close; listed causes are a defective switch or switch connection and wi…
Lockout
54
Air Proving Switch Failed to Open. The air proving switch is closed when it should be open; listed causes are a jumpered or defective air pr…
Lockout
54
Air Proving Switch Failed to Open. The air proving switch failed to open and the control went to a manual reset hard lockout; see the soft l…
Lockout
U.S. Boiler PVG power-vented cast-iron boilers (IQ Boiler Control error codes, I&O 103997-07)
2
Pressure Switch Failed to Open. While the blower is off the pressure switch failed to open (contact stuck closed); listed causes are wiring,…
Details
4
Flame Current Lower than Threshold. The flame current is lower than the threshold, so check the pilot assembly per the troubleshooting secti…
Lockout
6
Flame Sensed Out of Normal Sequence. Flame was sensed out of normal sequence, before opening the gas valve or after closing it, so check gas…
Details
18
Electronics Failure. The control electronics reported a failure, so cycle power to the control and replace it if the problem persists. The t…
Details
23
Flame Sensed During Pre-Purge. Flame was sensed during post-purge before the gas valve was signaled open, so check the gas valve for proper …
Details
29
Pressure Switch Failed to Close. While the blower is on the pressure switch failed to close; listed causes are a differential pressure below…
Details
32
Temperature Sensor Failure. Temperature sensor or interface failure (open or short connection, increased connection resistance, dual sensor …
Details
35
Duplicate Zone Alarm. A duplicate zone alarm was reported; refer to the IQ Zone Panel instructions. The table classifies it as Error.…
Details
57
Flame Rod Shorted to Burner Ground. The flame rod is shorted to burner ground, which can result from excessive flue gas condensation; check …
Lockout
58
AC Line Frequency Error. The AC signal is too noisy or its frequency is incorrect, so check the supply voltage. The table classifies it as E…
Details
59
Line Voltage Error. The AC voltage is out of specification high or low, so check the supply voltage. The table classifies it as Error.…
Details
60
Thermostat Input Higher than Threshold. The thermostat input is higher than the threshold, so check the thermostat wiring. The table classif…
Details
61
Line Voltage Unstable. Heavy loads switching on and off may cause an erratic supply voltage, so check the supply voltage. The table classifi…
Details
63
Soft Lockout - Maximum Recycles Exceeded. The maximum number of recycles was exceeded; refer to the troubleshooting section for recycles. Th…
Lockout
64
Soft Lockout - Internal Failure. The electronics detected an error, which can be caused by an actual controller internal fault or a wiring f…
Lockout
89
Communication Lost. Communication was lost, so check the wiring between the control and the IQ Zone Panel or IQ Reset Card. The table classi…
Details
Talk to a boiler technician
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.