Display shows E02 and water heater does not heat or shuts down shortly after opening a hot water tap.

Safety: Turn off power at the breaker and close the water supply before removing the cover.

• Locate the outlet NTC: Remove the front cover. The outlet temperature sensor is typically clipped or screwed onto the hot water outlet pipe and connected to the control board with two small wires.
• Check connection: Inspect the NTC plug at the control board. Unplug and replug to ensure a solid connection. Look for corrosion or moisture on the connector and dry if needed.
• Inspect sensor body: Check that the sensor is firmly attached to the outlet pipe and not physically damaged or covered in heavy scale. Clean light scale with a soft cloth.
• Test resistance (advanced): With power off, disconnect the sensor and measure resistance with a multimeter. Compare to the resistance/temperature chart in the service manual. A shorted (near 0 Ω) or open (infinite Ω) sensor must be replaced.
• Reset and test: Restore water and power, then run hot water. If E02 returns, replace the outlet NTC sensor with the correct Stiebel Eltron part. If a new sensor does not resolve the issue, the control board may be faulty and should be evaluated by a technician.