Heater stops heating and displays E02; unit may attempt to start and then shut down quickly.

Safety: Isolate power at the breaker and close the water supply before removing covers.

• 1. Access the NTC sensor: Remove the front cover. Locate the outlet temperature sensor (NTC) clipped or screwed into the hot-water outlet pipe or heat exchanger block.
• 2. Visual inspection: Check for signs of moisture, corrosion, or scale around the sensor. Ensure it is firmly seated in its well or clamp.
• 3. Check wiring: Follow the NTC leads to the main control board. Confirm the plug is fully inserted and wires are intact. Clean any oxidation on contacts with electrical contact cleaner.
• 4. Measure resistance: With power off and wires disconnected, measure the NTC resistance with a multimeter. Compare to Kospel’s service chart (typically several kΩ at room temperature). If reading is open, shorted, or far off spec, replace the NTC sensor.
• 5. PCB evaluation: If a known-good sensor still triggers E02, the temperature input circuit on the main PCB may be damaged. Replacement of the control board is usually required.

Do not bypass or short the sensor; this can cause overheating and serious damage.