E50
Rheem Internal Control Board Error

Rheem tankless water heater shows E50 and will not operate

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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

Corrupted firmware, Power surge damage, Moisture on PCB, Failed microcontroller

How to Fix / Troubleshooting

Safety first: Turn OFF power at the breaker.

  • Power cycle: Leave power OFF for 10 minutes, then restore and see if the error clears.
  • Inspect PCB: Remove front cover and look for signs of water damage, burnt components, or insect infestation on the main control board.
  • Check grounding: Ensure the unit is properly grounded and that line and neutral are correctly wired.
  • If E50 persists: The main control board likely needs replacement. Label all connectors, take photos, and swap the board with an identical Rheem replacement, or have a technician perform the work.
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Repair Difficulty

Hard 4/5

Required Part

Main Control Board
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