BoilerFaultCodesIdeal 48 Fault Code
The Ideal 48 fault code means: your boiler is failing to keep the pilot light burning after you let go of the ignition button, meaning the heating cannot start.. It appears on 1 Ideal model in our database.
Technical description: PILOT WILL NOT STAY LIT WHEN THE GAS CONTROL VALVE KNOB IS RELEASED
What causes the Ideal 48 fault?
This fault occurs when the boiler's safety monitoring system fails to detect a stable flame after the lighting process. The most common reason is a worn-out thermocouple that can no longer send a signal to the gas valve, or the overheat thermostat has tripped and cut the internal circuit to prevent damage. Essentially, the boiler shuts down the gas supply because it believes it is unsafe to stay running.
This issue often surfaces during the first cold spell of autumn when the boiler is switched back on after being idle during the summer months.
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 48 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 48 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