BoilerFaultCodesYour boiler has stopped working because it has detected a specific internal fault and has safely shut itself down as a precaution.
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, the display will be blinking alternating with a number and letter to show what kind of error is detected
What causes this fault?
This fault occurs when the boiler fails to light or cannot detect a flame after several attempts. The most common reasons include a lack of gas supply to the unit, a worn-out ignition spark, or a faulty sensor that cannot confirm the fire is burning safely. In some cases, it can also be caused by an internal electronic failure in the main control board.
While this can happen year-round, it is slightly more frequent in winter when gas pressure may fluctuate or internal components are under higher stress from constant use.
DIY fix possible
Check if your gas supply is active (e.g., check other gas appliances or your meter credit).Locate the reset knob or button on the front control panel.Turn the knob to the reset position for two seconds, then back to the desired temperature setting.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like L — no call-out fees, no surprises.
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