BoilerFaultCodesIdeal 27 Fault Code
The Ideal 27 fault code means: your boiler is unable to light the flame because the gas supply is blocked or a safety sensor is cutting out.. It appears on 2 Ideal models in our database.
Technical description: The first and/or second gas valve does not open, check for a 24 V supply during the ignition phase. Check the resistance of the burner thermostat (unit electrically disconnected) maximum resistance of 3Ω.
What causes the Ideal 27 fault?
This fault occurs when the boiler is unable to establishes a flame because the internal gas valves are failing to open or a safety sensor has detected overheating. The most common reason is an electrical failure in the gas valve motor or a tripped burner thermostat which acts as a safety cut-out to prevent damage. Essentially, the boiler is trying to start, but the 'gates' that allow gas into the burner are staying shut.
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 27 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 27 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