Heater displays E40 and will not fire in spa mode.

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.

Possible Causes

Failed spa temperature sensor, incorrect sensor wiring, misconfigured pool/spa mode settings.

Safety First: Turn off power before accessing sensors or control panel.

Verify mode selection: Ensure the front panel is correctly set to SPA mode and that any external automation is properly configured.
Locate spa sensor: Identify the dedicated spa temperature sensor (often installed in spa plumbing). Inspect its wiring for damage.
Test sensor: Measure resistance and compare it to Rheem's chart for the measured spa water temperature. Replace if out of range.
Check sensor assignment: Confirm that the control board terminals are wired to the correct pool and spa sensors and are not reversed.

Medium 3/5

Spa Temperature Sensor

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