Boiler shows E10 and shuts down during operation, often with hot supply temperature

Safety: Turn off power and allow the boiler to cool before touching sensors or piping.

• Locate supply sensor: The supply temperature sensor is usually clipped to the hot outlet pipe or inserted into a sensor well on the Dettson boiler.
• Inspect and reseat: Check the sensor body and wiring for damage. Reseat the connector at both the sensor and the control board.
• Dry moisture: If there are signs of condensation or water near the sensor or connector, dry the area thoroughly and correct any leaks.
• Sensor replacement: If E10 persists, the sensor may be out of tolerance. A technician can test resistance and replace the Dettson supply NTC sensor if necessary.
• Control board: Persistent E10 with a known-good sensor suggests a faulty control board, which should be replaced by a professional.