73
Noritz
Internal Control Board Configuration Error
Boiler displays error 73 and does not respond to user inputs.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Incorrect DIP switch settings, Corrupted control board memory, Incompatible replacement board
How to Fix / Troubleshooting
Safety: Turn OFF power before adjusting any internal switches.
- 1. Verify DIP switches: Remove the front cover and locate the DIP switches on the Noritz control board. Compare their positions to the installation manual for your specific boiler model and gas type.
- 2. Correct settings: If any switches are set incorrectly (e.g., wrong altitude or gas type), set them to the proper positions.
- 3. Power cycle: Restore power and see if the error clears.
- 4. Board compatibility: If a control board was recently replaced, confirm with the installer that the correct Noritz part number was used.
- 5. Professional reprogramming: Persistent error 73 may require board replacement or reprogramming by an authorized Noritz service provider.
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Repair Difficulty
Hard
4/5
Required Part
Main Control Board
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