BoilerFaultCodesYour boiler has stopped working and locked itself for safety because it has detected a specific internal fault.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Boiler is in lockout for a specific error. Display will be blinking, alternating with a number or letter to show which error is detected.
What causes this fault?
The 'L' code indicates a permanent lockout, which is a safety state triggered when the boiler's internal computer detects a critical failure. This usually happens when the burner fails to light after multiple attempts or if a vital component like the gas valve or circuit board stop communicating correctly. The boiler shuts down completely to prevent any potential safety risks and will not restart until the underlying hardware issue is resolved.
DIY fix possible
Check the display for a number or letter flashing after the 'L' (e.g., L2 or L5)Look up the specific instructions for the secondary code shownSwitch the boiler off and on again or press the 'Reset' button
Find a Gas Safe engineer
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