BoilerFaultCodesTechnical description
Return thermistor error
What causes this fault?
This fault occurs when the boiler's control board stops receiving a reliable signal from the sensor that monitors the temperature of the water returning from your radiators. The most common reason is that the sensor itself has developed an internal electrical failure, or the wiring connecting it to the main computer has become loose or damaged.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register →