Emergency Lockout
FA364 on Worcester Bosch Greenstar Si Combi / i System

Your boiler has detected a potential internal gas leak during its safety checks and has shut down to keep your home safe.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description

Gas valve EV2 leak test failed – gas valve leak

What causes this fault?

This fault occurs when the boiler's internal safety checks detect that gas is passing through the system when it should be shut off. The most common reason is a mechanical failure in the gas valve which prevents it from sealing properly, or a communication error from the main control board that incorrectly monitors the gas flow.

Engineer required

This is a emergency 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

EAView →F7View →E9View →

Related guides you might find useful

Boiler keeps losing pressure

Six most common causes of dropping pressure.

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 →