BoilerFaultCodesIdeal L-01 Fault Code
Also written as L01 — same fault.
The Ideal L-01 fault code means: your boiler has tried to fire up five times without success and has shut itself down for safety.. It appears on 1 Ideal model in our database.
Technical description: If, after 5 attempts the burner has failed to light, the boiler will go to lockout and L-01 will be displayed on the screen.
What causes the Ideal L-01 fault?
This fault occurs when the boiler cannot detect a flame after several attempts to start. The issue is typically caused by a lack of gas reaching the burner, a faulty ignition system failing to create a spark, or a dirty sensor that cannot confirm the fire is actually lit.
This fault is more frequent during the first cold snap of autumn when internal components or gas valves may stick after being dormant throughout the summer.
DIY fix possible
Check if other gas appliances (like a hob) are working to confirm gas supplyEnsure your gas meter has credit if you use a prepay meterPress the 'Reset' button on the control panel to try and clear the lockout
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Ideal models that show the L-01 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal L-01 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