If your Noritz combi boiler is showing error code 12, here's what it means: Flame failure (flame loss). This is an urgent fault. Stop using the boiler if it keeps recurring and book a licensed repair promptly — especially if it involves gas, ignition, overheating or the flue.
Noritz boilers report faults using numeric codes (e.g. 10, 11, 90). Knowing the code helps a technician arrive prepared with the right parts, which usually means a faster, lower-cost repair.
What causes the 12 code?
Error 12 on a Noritz boiler is most commonly caused by one of the following:
- Gas pressure
- Flame rod fouling
- Gas valve
What you can safely check first
- Note the exact code and your boiler's model number
- Check the pressure gauge — low pressure triggers many faults
- Confirm the gas supply is on and other gas appliances work
- Reset the boiler once, per the manual, only if it's safe to do so
- If the code returns, stop and call a licensed technician
Why this needs a licensed technician
Resolving a 12 fault almost always involves the gas, combustion, sensor or pressurized side of the appliance. Under BC's Safety Standards Act, that work must be performed by a licensed gas fitter — and doing it correctly protects your warranty and your safety. We diagnose Noritz boilers, carry common parts, and verify clean combustion before returning your boiler to service.
Smell gas or suspect carbon monoxide? Leave now.
If you smell gas, hear hissing, or your CO alarm sounds, leave the building immediately and call your gas utility's emergency line from outside. Do not operate switches or relight the appliance. Once you are safe, call us for a licensed repair.
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Fix Your Noritz 12 Fault
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