Rheem
Marginal Flame Detection / Weak Flame Signal
Boiler ignites but shuts down after a few seconds, with no specific error code displayed
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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
Dirty flame sensor, Poor burner grounding, Low gas pressure, Partially blocked burner ports
How to Fix / Troubleshooting
Safety first: Turn off power and gas before removing burner or flame sensor components.
- Step 1 – Clean flame sensor: Remove the flame sensor and gently clean the rod with fine abrasive pad until shiny. Reinstall ensuring it is fully in the flame.
- Step 2 – Check grounding: Verify that the boiler chassis is properly grounded and that burner mounting screws are tight and free of corrosion.
- Step 3 – Inspect burner: Remove the burner and check for rust, debris, or blocked ports. Clean per Rheem’s instructions.
- Step 4 – Gas pressure check: Have a qualified technician measure inlet and manifold gas pressures during operation. Correct any supply issues.
Warning: Do not bend the flame sensor excessively or damage its ceramic insulator. Replace if cracked.
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Repair Difficulty
Hard
4/5
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