E17
CTC
Tank Thermostat / Sensor Fault
Display shows E17 and unit cycles off on high temperature; tank feels extremely hot (electric models)
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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 tank temperature sensor, Miswired or bypassed thermostat, Stuck relay on control board, Scale buildup around sensor well
How to Fix / Troubleshooting
Safety first: Turn off power and allow the tank to cool. Open a hot water tap to relieve pressure.
Steps to check:
- Locate the tank temperature sensor or electronic thermostat on the side of the tank.
- Inspect wiring for modifications or bypasses; restore to factory configuration if altered.
- Remove the sensor from its well and check for heavy scale or corrosion. Clean the well and reinstall.
- Test the sensor resistance and compare to CTC specifications. Replace the tank temperature sensor if out of range.
- If the sensor is good but elements continue to heat beyond setpoint, the control relay on the main control PCB may be stuck closed and the board must be replaced.
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Repair Difficulty
Hard
4/5
Required Part
Tank Temperature Sensor
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