High Lockout
A05 on Vokera Condexa Pro

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

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 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.

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

Related guides you might find useful