BoilerFaultCodesIdeal 25 Fault Code
The Ideal 25 fault code means: your boiler is unable to create a spark to light the gas, meaning your heating and hot water will not work.. It appears on 4 Ideal models in our database.
Technical description: The connecting wires of the igniter do not make contact or the igniter is defective or the fuse F1 is defective. Control panel should supply 120 V to connector.
What causes the Ideal 25 fault?
This fault occurs when the boiler's control system attempts to start the heating process but cannot generate the electrical spark needed to ignite the gas. The most common reason is that the ignition components have worn out over time or a small internal fuse has blown, preventing power from reaching the burner. This results in a safety shutdown because the boiler cannot detect a flame.
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 25 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 25 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