41
Noritz
Freeze Protection Sensor Fault
Error code 41 displayed; unit may not start or may shut down unexpectedly.
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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
Failed freeze protection thermistor, Damaged wiring to freeze sensor, Sensor unplugged from PCB, Exposure to extreme conditions beyond design limits
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas. If the unit is in a freezing environment, protect plumbing from burst risk.
Steps to check and correct:
- Locate freeze protection sensor: On Noritz outdoor models, freeze sensors are typically attached to water pipes or the heat exchanger. Refer to the service manual.
- Inspect wiring: Look for rodent damage, UV damage, or loose connectors. Repair or replace as needed.
- Test sensor: Measure resistance at ambient temperature and compare to Noritz specs. Replace the freeze sensor if out of range.
- Check installation conditions: Ensure the unit is installed within the environmental limits specified by Noritz and that freeze protection power is maintained in cold weather.
- Reset and test: Restore power and run the unit. Persistent error 41 may indicate a PCB fault requiring professional service.
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Repair Difficulty
Medium
3/5
Required Part
Freeze Protection Sensor
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