38
Noritz
CO2 / Combustion Feedback Abnormality
Error code 38 appears; unit may not fire or may shut down shortly after ignition.
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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
Blocked or restricted exhaust, Incorrect gas type or manifold pressure, Dirty burner causing improper combustion, Faulty combustion feedback sensor or PCB logic
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas. Do not operate the unit if you suspect combustion or venting issues; risk of carbon monoxide exposure.
Steps to check and correct:
- Inspect venting: Follow the vent inspection steps from error 10. Ensure vent length, diameter, and terminations comply with Noritz specifications. Clear any obstructions.
- Verify gas type and pressure: Confirm the unit is set up for the correct gas type (NG or LP) and that the gas supply regulator is correct. A licensed technician should measure manifold pressure and adjust or replace regulators as needed.
- Clean burner assembly: Remove and inspect the burner for dust, rust, or debris. Clean with compressed air and a soft brush. Reinstall carefully.
- Professional combustion analysis: A Noritz-trained technician should perform a combustion analysis and verify CO2/O2 levels. If the combustion feedback sensor or PCB is faulty, they must be replaced with OEM parts.
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Repair Difficulty
Professional Required
5/5
Required Part
Burner Assembly
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