E13
Rheem Water Temperature Differential / Sensor Mismatch

Heater displays E13; may occur when switching between pool and spa modes

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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

Inlet and outlet sensors reading unrealistic temperature difference, Cross-connected sensors, Rapid flow changes due to valve actuators

How to Fix / Troubleshooting

Safety First: Disconnect power before accessing sensors or control board.

  • Verify plumbing configuration: Ensure that the heater is plumbed correctly with proper inlet and outlet orientation and that valves are not causing short-circuiting of flow.
  • Check sensor placement: Confirm that the inlet and outlet temperature sensors are installed in the correct ports and wired to the correct terminals on the control board.
  • Inspect for air in system: Air pockets can cause erratic temperature readings. Bleed air from high points in the plumbing and ensure the pump is fully primed.
  • Test sensors: Measure resistance of both sensors and compare to each other and to Rheem charts. Replace any sensor that is significantly out of range.
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Repair Difficulty

Medium 3/5

Required Part

Temperature Sensor Set
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