BoilerFaultCodesYour boiler is failing to light the gas burner and has gone into a safety lockout mode to prevent unburned gas from building up.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: The lockout light will be illuminated at the end of the 4 second ignition period and the fan will run on.
What causes this fault?
This fault occurs when the boiler's control system attempts to start the heating process but cannot detect a stable flame. The most common reasons are a lack of spark from a worn ignition lead or the gas valve failing to open and deliver fuel to the burner. Because the boiler cannot confirm the gas has lit safely, it shuts down to prevent any hazards.
This issue is frequently seen during the first cold snap of autumn when internal components like the gas valve can stick after being inactive over the summer months.
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 Burner fails to light — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Ideal Concord Super Series 4 is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.