High Lockout
F004 on Intergas Xclusive 24

Your boiler is failing to light the gas flame required to provide heating and hot water.

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

No flame during start-up.

What causes this fault?

This fault occurs when the boiler's control system attempts to start the combustion process but cannot detect a stable flame. The most common reasons are a lack of gas supply to the unit, a worn-out ignition spark, or a build-up of carbon on the internal probes that monitor the fire. Without a confirmed flame, the boiler stops for safety reasons to prevent unburnt gas from entering the system.

This fault can occur more frequently during the first cold snap of autumn when internal components that have been dormant all summer are suddenly required to work under high load.

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