Boiler displays H17, often related to flue gas temperature or sensor issues.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Faulty flue gas temperature sensor, Blocked or restricted flue, Incorrect flue installation, PCB sensor input fault

Safety first: Do not attempt to dismantle the flue. Isolate power if you suspect flue gas leakage and ventilate the area.

Visual flue check: From outside, ensure the flue terminal is clear and not damaged.
Reset boiler: Perform a single reset and observe operation.
Engineer tasks: A Gas Safe engineer should test the flue gas sensor, inspect the flue for blockages or incorrect falls, and replace the sensor or rectify the flue as needed.

Professional Required 5/5

Flue Gas Temperature Sensor

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