99
Noritz
Flame Detection Failure at Ignition
Boiler displays error 99 and locks out; may be accompanied by strong exhaust smell.
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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
No flame at burner, Igniter failure, Gas supply interruption, Flame rod not sensing flame
How to Fix / Troubleshooting
Critical safety: If you smell gas or see signs of incomplete combustion, shut OFF gas and power and ventilate the area. Do not attempt repeated restarts.
- 1. Verify gas supply: Confirm gas shutoff valves to the Noritz boiler are open and other gas appliances function.
- 2. Inspect igniter and flame rod: With power and gas OFF, remove the front cover and inspect the igniter and flame rod for cracks, heavy deposits, or loose wiring. Clean or replace as needed.
- 3. Check venting: Ensure intake and exhaust are not blocked, which can prevent proper ignition.
- 4. Professional service: Persistent error 99 requires a technician to test ignition voltage, gas pressure, and flame sensing circuits.
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Repair Difficulty
Professional Required
5/5
Required Part
Igniter and Flame Rod Assembly
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