BoilerFaultCodesTechnical description
Temperature too high during DHW demand.
What causes this fault?
This fault occurs when the water temperature within the boiler climbs too quickly or exceeds safe limits while you are using your hot water. It is usually caused by a blockage or a component failure that prevents heat from being transferred away from the burner and into your taps effectively. Common culprits include a faulty temperature sensor giving incorrect readings or a stuck diverter valve that isn't directing the hot water where it needs to go.
This fault can be more noticeable in summer when the incoming mains water is naturally warmer, giving the boiler less 'room' to manage high temperatures before hitting a safety limit.
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.