E20 displayed; Sime water heater indicates sensor mismatch or calibration error.

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

Incorrect NTC type fitted, Poor thermal contact of sensor, Control board calibration error, Wiring cross-connection between sensors

Safety: Turn off power before working on sensors.

Steps:

Verify correct sensors: If a sensor was recently replaced, ensure it is a genuine Sime NTC with the correct specification.
Check mounting: Ensure sensors are firmly clipped to pipes or fully inserted into wells with thermal paste if specified.
Check wiring order: Confirm that DHW and inlet NTC connectors are not swapped on the PCB.

Professional help: If E20 persists, a Sime technician may need to recalibrate or replace the control board.

Hard 4/5

DHW and Inlet NTC Sensors

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