High Lockout
F62 on Glow-worm Ultracom 2 CXI

Your boiler has detected an internal electronics failure that prevents it from safely controlling the gas supply, meaning it has shut down for safety.

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

Main PCB gas valve shutdown fault

What causes this fault?

This fault occurs when the boiler's main control board detects a safety timing issue or an electrical failure when trying to shut off the gas valve. It is typically caused by a malfunctioning circuit board that can no longer communicate correctly with the valve, or a valve that is physically sticking and failing to close when prompted.

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 fault codes

F61View →F63View →F64View →F65View →

Related guides you might find useful

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Pilot light keeps going out

Older boilers — thermocouple, draught, gas supply.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →