Classeq dishwasher stops and shows E5; rinse boiler does not reach temperature or rinse cycle aborted.

Safety first: Isolate power and allow the machine to cool fully. The boiler and associated pipework can be extremely hot and under pressure.

• Check for descaling needs: If the machine has not been descaled regularly and is in a hard‑water area, heavy limescale on the boiler heater can cause slow heating and E5. Plan a full professional descale if scale is visible.
• Access the rinse boiler: Remove the top or side panel to locate the stainless‑steel rinse boiler. Identify the immersion heater, NTC sensor, and safety thermostat.
• Test boiler heater: Disconnect the heater leads and measure resistance. Compare with Classeq specifications. Infinite resistance or visible burn marks indicate a failed heater that must be replaced.
• Check boiler NTC sensor: Measure resistance at room temperature and again after gently warming the sensor (e.g., with a hairdryer, not an open flame). The resistance should change smoothly. Replace if open, shorted, or erratic.
• Inspect safety thermostat / cut‑out: Some Classeq models have a manual reset thermostat on the boiler. Press the reset button if present. If it trips repeatedly, investigate scaling or heater overrun.
• Verify wiring and relays: Check all spade connectors to the boiler heater and NTC. Inspect the control PCB heater relay for signs of overheating.