Heater shows E11 and does not respond to thermostat changes
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.
Possible Causes
How to Fix / Troubleshooting
Safety first: Disconnect power before accessing sensors or the control board.
- Confirm correct sensor part: Check that any recently replaced water temperature sensor is a genuine BWT part with the correct resistance curve for your model.
- Inspect connections: Ensure all NTC sensor connectors are fully seated on the control board and free of corrosion.
- Check for mixed sensors: Verify that inlet and outlet sensors have not been swapped accidentally. Refer to the wiring diagram on the unit.
- Power cycle: Turn power off for 5 minutes, then restore and see if E11 clears.
If E11 remains, the sensor(s) may be out of tolerance or the control board may require firmware update or replacement. Contact BWT support or a qualified technician.
Repair Difficulty
Required Part
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