BoilerFaultCodesIdeal Ignition Lockout 1/2 Fault Code
Also written as IGNITIONLOCKOUT12 — same fault.
The Ideal Ignition Lockout 1/2 fault code means: your boiler has tried to light several times but failed, so it has locked itself for safety to prevent gas from building up.. It appears on 1 Ideal model in our database.
Technical description: Ignition lockout (screen 1 of 2) — check gas supply, restart
DIY fix possible
Check that your gas emergency control valve (usually located by the gas meter) is open.Check if other gas appliances, like a hob, are working to confirm your gas supply is active.Press and hold the 'Restart' button for two seconds to allow the boiler to try lighting again.
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Ideal models that show the Ignition Lockout 1/2 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal Ignition Lockout 1/2 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 7 July 2026