Noritz · Water heater
Code 73 Circuit board setting error
What this code means
The control board's dip switch or jumper configuration doesn't match what's expected — distinct from Code 70's general board fault.
Most likely causes
- Dip switch or jumper changed while powered
- Improperly programmed board after service
What to try first
Have a technician verify the dip switch settings match the installation manual for your specific model.
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 73 mean?
Circuit board setting error. The control board's dip switch or jumper configuration doesn't match what's expected — distinct from Code 70's general board fault.
Can I fix Noritz code Code 73 myself?
Usually not. Have a technician verify the dip switch settings match the installation manual for your specific model. If the code returns after one reset, it needs a licensed technician.
What causes Noritz code Code 73?
The most common causes are: dip switch or jumper changed while powered; improperly programmed board after service.
Other Noritz water heater codes
All Noritz water heater error codes →
Other water heater brands: Rheem · Ruud · Rinnai · Navien · Takagi · A.O. Smith · Bradford White · State / American · Generic electric · Generic tankless
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.