High Lockout
234 on Worcester Bosch Greenstar 8000 Life/Style

Your boiler has detected an electrical problem with the component that controls the gas supply, meaning it cannot safely light the burner to provide heat or hot water.

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

Gas valve electrical fault

What causes this fault?

This fault occurs when the boiler's main control board detects an unexpected electrical signal or a total loss of communication with the gas valve. The most common reason is an internal electrical failure within the valve itself or a loose connection in the wiring that prevents the system from safely managing the flow of fuel. Because the boiler cannot guarantee the burner will light correctly, it shuts down as a safety precaution.

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

232View →

Related guides you might find useful

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 →

Pilot light keeps going out

Older boilers — thermocouple, draught, gas supply.

Read →