BoilerFaultCodesTechnical description
Fault codes 5x appear if a problem with the main board exists.
What causes this fault?
This fault occurs when the boiler’s main control board suffers a critical electronic failure or loses communication with its internal sensors. It is usually caused by age-related degradation of the circuit components or a sudden electrical surge that damages the board's memory. Because the 'brain' can no longer guarantee the boiler is operating safely, it shuts the entire system down as a precaution.
While this can happen at any time, it is slightly more common during stormy weather when power surges or lightning strikes can cause electrical damage to the sensitive circuit 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.