BoilerFaultCodesTechnical description
The heating return thermistor is short circuited.
What causes this fault?
This fault occurs when the sensor responsible for measuring the temperature of the water coming back from your radiators fails or develops an electrical fault. The most common reason is that the internal components of the sensor have degraded over time or moisture has compromised the electrical connection, causing it to send a faulty signal to the main control board.
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.
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