Water heater
Noritz water heater error codes
Every Noritz water heater code in our database, with plain-English meanings, likely causes, and what to try before calling for service. Codes can vary by model and year — always confirm against the legend on your unit or its manual.
- Code 10 Flame failure / flame loss
- Code 11 Ignition failure
- Code 16 Abnormally high outlet temperature
- Code 20 High limit switch triggered
- Code 29 Condensate drainage problem
- Code 31 Cold water inlet thermistor abnormality
- Code 32 Hot water outlet thermistor abnormality
- Code 33 Heat exchanger outlet thermistor abnormality
- Code 35 Exhaust thermistor abnormality
- Code 45 Internal water leak detected safety
- Code 51 Gas manifold solenoid valve fault
- Code 52 Exhaust blockage
- Code 61 Fan motor abnormality
- Code 63 Recirculation pump abnormality
- Code 65 Main water servo abnormality
- Code 66 Bypass water servo abnormality
- Code 67 Air-gas mixer (AGM) abnormality
- Code 70 Circuit board abnormality
- Code 73 Circuit board setting error
- Code 90 Combustion abnormality
- Code 903 Combustion abnormality (sub-code)
- Code 91 Incorrect gas type
- Code 92 Neutralizer life cycle warning