E12
Rheem
Flame Loss During Operation
Rheem tankless water heater displays E12 and shuts down 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
Unstable gas pressure, Blocked vent or intake, Dirty burner, Faulty flame sensor
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas. Allow the unit to cool.
- Check venting and intake: Inspect for obstructions, improper vent length, or sagging vent pipes that can cause condensation and flame instability.
- Verify gas supply stability: If other gas appliances flicker or go out, contact your gas supplier to check pressure.
- Clean flame sensor and burner: Access the burner and flame rod. Clean the flame rod with fine abrasive pad and blow dust out of the burner with compressed air.
- Check condensate drain (condensing models): Ensure the condensate trap and drain line are not blocked, which can affect combustion.
- If E12 recurs: A technician should check gas valve modulation, combustion analysis, and control board operation.
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Repair Difficulty
Hard
4/5
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