BoilerFaultCodesTechnical description
Printed circuit board (PCB) lockout error
What causes this fault?
This fault occurs when the boiler's control board experiences a communication failure or an internal memory error, often caused by unstable electrical supply or aging components. It essentially means the boiler is 'confused' by inconsistent data and has shut down as a safety precaution to avoid operating unpredictably.
This fault is more common during winter months or stormy weather, as power surges, local grid fluctuations, and damp conditions can interfere with sensitive electrical components.
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 →