BoilerFaultCodesIdeal 6L Fault Code
The Ideal 6L fault code means: your boiler is successfully lighting, but it cannot stay lit and keeps cutting out while it is running.. It appears on 1 Ideal model in our database.
Technical description: The ionisation (the flame) extinguishes during operation of the unit.
What causes the Ideal 6L fault?
This fault occurs when the boiler successfully starts but cannot maintain a stable flame, leading the safety sensors to shut the system down. The most common reasons are a worn-out sensor that can no longer 'see' the flame or an inconsistent gas supply that causes the fire to flutter and go out. It can also be caused by a buildup of carbon on the internal components which interferes with the electrical signal required to keep the boiler running.
This fault is often seen during the first cold snap of autumn when the boiler is pushed to run for longer periods after being mostly idle throughout the summer.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ideal models that show the 6L fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 6L 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