BoilerFaultCodesIdeal Lock-out signal lamp E blinks Fault Code
Also written as LOCKOUTSIGNALLAMPEBLINKS — same fault.
The Ideal Lock-out signal lamp E blinks fault code means: your boiler has tried to start up but failed to ignite the gas flame, causing the system to shut down for safety.. It appears on 6 Ideal models in our database.
Technical description: The burner did not light within 20 seconds. Refer to the 'Fault Finding' section.
What causes the Ideal Lock-out signal lamp E blinks fault?
This fault occurs when the boiler's internal computer tries to start the combustion process but cannot detect a stable flame within the safety timeframe. It is often caused by a lack of gas reaching the burner, a build-up of carbon on the spark electrodes, or a worn-out sensor that can no longer 'see' the flame even if it has lit.
This issue can occur more frequently during the first cold snap of winter, as gas valves may stick after sitting idle during the summer months.
DIY fix possible
Check that your gas prepay meter has creditEnsure other gas appliances in your home (like a hob) are workingPress the reset button once to see if the boiler restarts
Find a Gas Safe engineer
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Gas Safe Register →Ideal models that show the Lock-out signal lamp E blinks fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal Lock-out signal lamp E blinks fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026