E11
Rheem No Ignition / Ignition Failure

Rheem tankless water heater shows E11 and shuts down immediately after trying to start

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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 gas supply, Clogged burner orifice, Faulty igniter, Incorrect gas type or pressure

How to Fix / Troubleshooting

Safety first: Turn OFF power and gas. Do not repeatedly attempt ignition with a suspected gas issue.

  • Verify gas supply: Ensure the manual gas shutoff valve is open. Check that other gas appliances operate normally.
  • Check gas type and pressure: Confirm the heater is configured for the correct gas (natural gas vs LP) and that the gas regulator is properly set. This typically requires a manometer and should be done by a technician.
  • Inspect igniter: Remove the front cover and burner access. Check the igniter for cracks, heavy scale, or damage. Replace if defective.
  • Clean burner: If accessible, gently clean burner ports with compressed air to remove dust and debris.
  • If E11 continues: Professional diagnosis of gas valve operation, combustion, and control board is recommended.
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Repair Difficulty

Professional Required 5/5

Required Part

Igniter
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