Noritz · Water heater
Code 51 Gas manifold solenoid valve fault
What this code means
The gas manifold solenoid valve has failed or is malfunctioning, often due to water intrusion or low inlet gas pressure — a hard lockout requiring professional repair.
Most likely causes
- Water intrusion into the gas manifold assembly
- Low inlet gas pressure
- Failed solenoid valve
What to try first
Not a DIY repair given the gas and combustion components involved.
Safety note: if this code returns after one clean reset, stop resetting it — repeated lockouts usually mean a real fault that needs a licensed technician. Never bypass a safety switch.
FAQ
What does Noritz error code Code 51 mean?
Gas manifold solenoid valve fault. The gas manifold solenoid valve has failed or is malfunctioning, often due to water intrusion or low inlet gas pressure — a hard lockout requiring professional repair.
Can I fix Noritz code Code 51 myself?
Usually not. Not a DIY repair given the gas and combustion components involved. If the code returns after one reset, it needs a licensed technician.
What causes Noritz code Code 51?
The most common causes are: water intrusion into the gas manifold assembly; low inlet gas pressure; failed solenoid valve.
Other Noritz water heater codes
All Noritz water heater error codes →
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This information may contain errors or not apply to your exact model — always double-check it against your appliance's own manual before acting. If there's any chance of a gas, fire, electrical, carbon monoxide, or other safety hazard, stop and call a licensed professional or the appropriate agency (e.g. your gas utility) instead of relying on this page alone.