SEN
Raypak Water Temperature Sensor Fault

Display shows SEN, SENSOR, or a similar code; unit may not start or may shut down intermittently.

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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 thermistor sensor, Shorted or open sensor wiring, Sensor not fully inserted into well, Corroded connector at control board

How to Fix / Troubleshooting

Safety first: Disconnect power before accessing the control board or sensor wiring.

  • Locate the sensor: Find the water temperature sensor on the Raypak manifold (often in a threaded well or clip). Ensure it is fully seated and not loose.
  • Inspect wiring and connector: Follow the sensor cable to the control board. Reseat the connector and look for corrosion or moisture. Dry and clean as needed.
  • Resistance check: Using a multimeter and the Raypak service chart, measure the sensor resistance at a known water temperature. If the reading is far off spec, replace the sensor.
  • Replace sensor: Shut off water, relieve pressure, remove the old sensor, apply appropriate sealant if threaded, and install the new Raypak sensor. Restore water and check for leaks before powering up.
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Repair Difficulty

Medium 3/5

Required Part

Water Temperature Sensor
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