Your boiler has detected an internal electrical fault with the component that controls the gas supply, meaning it cannot safely ignite.

Gas valve relay error

What causes this fault?

This fault occurs when the boiler's main control board detects a failure in the electrical circuit that opens and closes the gas valve. The most common reason is that the physical relay on the circuit board has worn out or become stuck, preventing the boiler from safely managing the flow of fuel. Because the system can no longer guarantee the gas will shut off correctly, it stops operating as a safety precaution.