Noritz Error 90: Combustion Abnormality
The fuel/air mixture is not balanced correctly (a combustion gas alert). The unit detects abnormal combustion and shuts down. Error code 903 is the same condition flagged as more severe. We diagnose and repair it across Greater Vancouver — same-day and after-hours.
The fuel/air mixture is not balanced correctly (a combustion gas alert). The unit detects abnormal combustion and shuts down. Error code 903 is the same condition flagged as more severe.
Noritz fault codes can vary by model and series. Use this as a guide — the same code can have more than one cause. Our Technical Safety BC–licensed technicians read the code, confirm it against your unit's manual, and diagnose the true cause before any repair.
Likely causes of Noritz error 90
- Blocked or restricted intake/exhaust venting
- Dirty gas burner or fouled heat exchanger surfaces
- Incorrect gas supply pressure
- Faulty air-gas mixer / fan affecting the mixture (premix models)
- Improper combustion setup or wrong gas type
What you can safely check
- Inspect outside intake/exhaust terminals and clear any blockage
- Confirm the gas supply is on and other gas appliances work
Beyond these checks, do not open the unit or touch gas/electrical parts — BC law requires a licensed gas fitter. Call us for a proper diagnosis.
Error 90 usually leaves you without heat or hot water and can indicate a safety-related fault. Don't keep resetting it — call for priority after-hours Noritz repair.
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For your safety and to keep your manufacturer warranty valid, BoilerPart.ca does not sell loose boiler parts over the counter or for self-installation. Under BC regulations, gas appliance components must be installed by a licensed gas fitter. Every part we source is genuine OEM and is professionally fitted, tested, and certified by our Technical Safety BC–licensed technicians as part of a complete repair or installation.
Parts often behind Noritz error 90
Genuine Noritz parts we supply and professionally install — never for DIY.
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Noritz Error 90 Repair Across Metro Vancouver
Related Noritz Venting & Combustion Codes
Frequently Asked Questions
Fix Noritz Error 90 Today
Licensed Noritz diagnosis and repair with genuine parts — same-day and after-hours across Greater Vancouver.
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