E17
Comenda Tank Overtemperature / Thermostat Fault

Excessive tank temperature; machine may stop heating and show E17.

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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

Stuck heating relay or contactor, Faulty tank thermostat or NTC, Failed safety thermostat not tripping, Control board logic fault

How to Fix / Troubleshooting

Safety first: Isolate power and allow the tank to cool fully before inspection.

  • Check actual temperature: Use an external thermometer to verify tank temperature. If it is significantly above setpoint, suspect control issues.
  • Inspect relays/contactors: In the electrical panel, check if the heater contactor is welded closed (contacts stuck). Replace if it remains engaged with no control signal.
  • Test thermostats: Verify that the safety thermostat has not failed closed. Replace if it does not open at its rated temperature.
  • Sensor check: Confirm the tank NTC is reading correctly; a faulty sensor can cause overheating.

Overheating can be dangerous; if unsure, contact a qualified technician.

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Repair Difficulty

Professional Required 5/5

Required Part

Tank Safety Thermostat
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