Digital Drazice electric water heater will not heat; display shows E1 and heating icon is off.

Safety first: Switch OFF the circuit breaker feeding the Drazice heater and verify no voltage at the terminal block with a multimeter before opening any covers.

Steps to check the NTC sensor:

• Remove the front service cover to access the electronic thermostat/control board and sensor terminals (usually inserted into a dry well on the tank).
• Locate the NTC temperature sensor leads (refer to the wiring diagram on the heater cover; typically labeled NTC or sensor).
• Disconnect the sensor plug from the control board and measure resistance across the sensor with a multimeter. At room temperature (~20–25°C), most Drazice NTCs should read in the tens of kΩ range (check the technical label or manual for exact value).
• If the reading is infinite (open) or near 0 Ω (short), the sensor is defective and must be replaced.
• Inspect the sensor cable for cuts, crushed insulation, or signs of overheating. Repair or replace damaged wiring.
• Clean any oxidation from the connector pins on the control board and reseat the plug firmly.
• Install a new OEM Drazice NTC sensor into the sensor well, ensuring it is fully inserted and clamped as designed.
• Restore power and clear the error by switching the heater OFF/ON at the main switch or breaker. Monitor operation and verify that the E1 code does not return.

If E1 persists after sensor replacement, the fault may be on the control board input circuit; contact a qualified technician.