SEn
Heat Siphon Temperature Sensor Fault (Water or Air)

Display shows “SEn” or “SEN ERR”; unit will not run or cycles erratically.

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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

Open or shorted temperature sensor, Damaged sensor wiring harness, Faulty control board sensor input

How to Fix / Troubleshooting

Safety first: Turn off power at the breaker before testing sensors.

  • Identify which sensor: Consult the Heat Siphon service label or manual to determine if SEn refers to water, air, or coil sensor on your model.
  • Inspect wiring: Trace the sensor cable from the manifold or coil to the control board. Look for cuts, abrasions, or rodent damage. Reseat connectors.
  • Measure resistance: Disconnect the sensor and measure its resistance with a multimeter. Compare to the Heat Siphon temperature/resistance chart for the current temperature.
  • Replace sensor: If readings are far off spec or open/shorted, replace the sensor with an OEM Heat Siphon part.
  • Control board: If a known‑good sensor still triggers SEn, the control board may be defective and should be evaluated by a technician.
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Repair Difficulty

Medium 3/5

Required Part

Temperature Sensor
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