E31
Rheem Line Frequency / Power Quality Fault

Heater intermittently shuts down with E31 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

Unstable power supply, Generator power with poor regulation, Control board sensitivity to frequency variations

How to Fix / Troubleshooting

Safety First: Disconnect power before inspecting wiring.

  • Check power source: If running on a generator or inverter, verify it provides stable voltage and 60 Hz frequency (or local standard). Poor-quality power can cause E31.
  • Inspect wiring runs: Long undersized runs can cause voltage fluctuations. Upgrade wiring to the correct gauge if necessary.
  • Install surge protection: Consider adding a whole-house or dedicated surge protector to protect the heater's electronics.
  • Consult electrician: Persistent E31 indicates a power quality issue that should be evaluated by a licensed electrician.
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Repair Difficulty

Medium 3/5

Required Part

Main Control Board
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