BoilerFaultCodesTechnical description
S2 sensor short circuit
What causes this fault?
This fault occurs when the boiler's control system detects that the S2 temperature sensor has developed an electrical short circuit, meaning it can no longer safely track the heat level. The most common reason is that the sensor's internal components have failed due to age or heat stress, or moisture has compromised the electrical connections. Because the boiler doesn't know the exact temperature of the water, it shuts down as a safety precaution to prevent overheating.
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 →