High Lockout
power on Grant Vortex Pro Combi 26

Your boiler has lost electrical power and cannot start any heating or hot water functions.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

If the boiler is not lit it could be a problem with power supply to the boiler switched off or possibly blown a fuse

What causes this fault?

This fault occurs when the boiler is not receiving the electrical current required to operate its internal components. The most common reason is a simple blown 3-amp fuse in the fused spur switch or a tripped circuit breaker in your home's main consumer unit. In more serious cases, it can be caused by a surge that has damaged the boiler's 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.

Find a Gas Safe engineer
Search the official register →

Related guides you might find useful

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →