BoilerFaultCodesYour boiler has detected an issue with the gas pressure or a component failure and has shut down as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Burner control switches to lockout
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the gas pressure is either too low or fluctuating, preventing the burner from staying lit. It is often caused by a failing gas valve that can't regulate the flow properly or worn ignition electrodes that are struggling to spark. In some cases, the main control board has developed a communication error and can no longer safely manage the combustion process.
This fault can be more frequent during extreme cold snaps when high local demand for gas can cause drops in mains pressure, or when debris in the gas line settles during the first heavy use of the winter.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 0A — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
Affiliate links — we may earn a commission at no extra cost to you.