High Lockout
F0238 on Worcester Bosch CDi Classic

Your boiler has detected an internal electrical problem with the component that controls the gas supply, causing the system to 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

Gas valve or control box error – gas valve coils need checking

What causes this fault?

This fault occurs when the boiler's main computer loses reliable communication with the gas valve, which is the component responsible for releasing fuel into the burner. The most common reason is an internal electrical failure within the valve's coils or a fault on the circuit board that prevents it from sending the correct voltage to start the heating process.

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

F0View →EAView →C6View →

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 →