E8
Rheem
Fan Motor / Combustion Blower Fault
Rheem tankless water heater shows E8 and shuts down during operation
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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
Failed combustion fan motor, Blocked fan wheel, Loose fan connector, Faulty fan speed feedback sensor
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas. Allow the unit to cool.
- Listen for fan: When starting, you should hear the combustion fan spin up. If it is silent or makes grinding noises, suspect the fan.
- Inspect fan assembly: Remove the front cover. Locate the combustion blower. Check for debris, insect nests, or foreign objects in the fan wheel.
- Check wiring: Ensure the fan motor connector is fully seated on the motor and control board.
- Spin test: With power OFF, gently spin the fan wheel by hand. It should rotate freely without binding. If stiff or noisy, replace the fan motor assembly.
- Advanced testing: A technician can verify fan voltage and tachometer feedback. If the board is not sending power or not reading speed, the main control board may be faulty.
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Repair Difficulty
Hard
4/5
Required Part
Combustion Blower Motor
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