Code 99
Rinnai
Flame Loss / Flame Detection Error
Unit displays Code 99 and shuts down; may be intermittent
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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
Unstable gas supply, Dirty flame rod, Poor grounding, Faulty control board flame circuit
How to Fix / Troubleshooting
Safety first: Turn OFF gas and power. Do not continue to reset the unit if flame loss recurs.
Steps to check:
- Check gas supply: Ensure gas valves are fully open and supply is stable.
- Clean flame rod: Remove and gently clean the flame rod with fine abrasive pad.
- Verify ground: Confirm the unit is properly grounded at the electrical connection.
- Reset and test: Restore power and gas and reset the unit.
When to call a professional: Persistent Code 99 requires a technician to evaluate gas pressure, combustion, and control board.
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Repair Difficulty
Hard
4/5
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