Utica cast iron LIMITS (blinking) — External Limits Open
LIMITS (blinking)
External limits open. The LIMITS light illuminates on a call for heat when external limits are satisfied; if the external limits are open (flame rollout, spill switch, secondary low water cut-off, etc.) the LIMITS light blinks. Check the external limit circuit. The table classifies it as fault.
If a carbon-monoxide alarm sounds
- Leave the building immediately and get fresh air.
- Call 911. Do not go back inside until emergency services say it is safe.
- Have every fuel-burning appliance inspected before use.
Only after that, call ROMA about the boiler. Official guidance: Health Canada on carbon monoxide.
Applies to
This overheating code is displayed by the HydroStat-style control (LED diagnostics) on MGB-K and MGC Series 4 cast-iron models, as documented in Utica MGB/DXL Boiler Manual, doc 240013750 Rev B (LED diagnostics) — MGC Series 4 in 240013818 Rev A (240013750 Rev B). Codes can differ between controller generations, so always check the manual that matches your unit.
- Utica Boilers MGB-K (MGB Series)
- Utica Boilers MGC Series 4 (MGC-8D/9D)
- Utica MGB-060K
- Utica MGB-095K
- Utica MGB-120K
- Utica MGB-150K
- Utica MGB-175K
- Utica MGB-205K
- Utica MGB-235K
- Utica MGC-8D
- Utica MGC-9D
Controller: HydroStat-style control (LED diagnostics). Source manual: 240013750 Rev B.
Why a code is not a diagnosis
An over-temperature code protects the heat exchanger or venting; it does not reveal whether the cause is low water flow, a failed pump, trapped air, fouling or a sensor fault.
Safe things to observe
- Note the code and whether rooms or hot water are still working.
- If you see steam, melted wiring or smell burning, switch the appliance off at its service switch and call a technician.
Do not
- Do not reset the appliance repeatedly while the cause is unknown.
- Do not remove covers or bypass any high-limit device.
How professional service helps
- A technician checks pump operation, flow, system pressure and the cleanliness of the heat exchanger.
- Combustion and safety devices are verified with an analyser and the manufacturer's procedure after any repair.
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Parts and service
Parts commonly involved
These parts appear in the documented text for this alert. A code reports a condition, not a failed part — a technician confirms the cause by testing before anything is replaced.
Flame rollout switch
A flame rollout switch is a one-time safety device that shuts a boiler down when flame or hot gas escapes the combustion chamber instead of passing…
What a technician checks →Spill switch / blocked-vent switch
A spill switch, also called a blocked-vent switch, shuts down an atmospheric boiler when flue gases spill from the draft hood instead of rising up…
What a technician checks →Low-water cutoff
A low-water cutoff is the safety device that stops a boiler from firing when there is not enough water inside it.
What a technician checks →
Service for this alert
- Gas Boiler Repair
Licensed gas technicians from ROMA Heating & Cooling diagnose and repair residential and light-commercial gas boilers across…
Every boiler part explained — what it does, how it fails and what a technician checks.
Documented for Utica Boilers MGB-K (MGB Series) and Utica Boilers MGC Series 4 (MGC-8D/9D).
Frequently asked questions
Is this code a carbon-monoxide danger?
The code relates to combustion or venting, so treat any CO alarm as an emergency and call 911 from outside. The appliance itself should be checked by a technician before it runs again.
Can I clear this code myself?
Clearing a code without fixing its cause usually just brings it back. Note the code, check the safe items on this page, then call a licensed technician. If your appliance manual describes a user reset for this exact code and it stays away, no call may be needed.
Boiler locked out? Call with the alert text ready.
The brand, model and this alert are passed along when you request service online, so the technician arrives prepared.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- Utica MGB/DXL Boiler Manual, doc 240013750 Rev B (LED diagnostics) — MGC Series 4 in 240013818 Rev A · 240013750 Rev B · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.