How to Fix / Troubleshooting

Power off: Isolate the heater from mains before opening any covers.

Check the outlet sensor:

Identify the outlet (hot water) NTC sensor; it is usually installed in a dry well near the hot water outlet connection or on the flange plate.
Disconnect the sensor from the control board and measure its resistance at ambient temperature. Compare with the specification in the Drazice manual.
If resistance is out of range, replace the outlet NTC sensor with an OEM part.
Inspect the cable for cuts, pinched sections, or signs of water ingress. Replace the cable if damaged.
Ensure the sensor is fully inserted into its well and secured with the original clip or screw so it senses water temperature correctly.
Dry any moisture around the connector and board; if there are signs of water leaks, locate and repair the leak before reassembly.
Restore power and verify that the E3 code clears and temperature readings are stable.

Drazice electronic water heater displays E3 and stops heating; sometimes accompanied by irregular temperature readings.

Possible Causes