BoilerFaultCodesIdeal LED3 on PCB 37 Fault Code
Also written as LED3ONPCB37 — same fault.
The Ideal LED3 on PCB 37 fault code means: this light is actually a positive signal showing that your boiler's internal electrical fuse is working correctly and the control board has power.. It appears on 1 Ideal model in our database.
Technical description: Lit confirms the fuse is good on PCB 37.
What causes the Ideal LED3 on PCB 37 fault?
This light is not actually a fault, but a status indicator showing that the boiler is receiving electrical power. It confirms that the internal glass fuse is intact and the circuit board is functioning as intended. If your boiler is not working while this light is on, the issue lies with a different component or external control rather than the power supply.
DIY fix possible
No action required as this light indicates a healthy electrical connection to the board.If the boiler is not working despite this light being on, check that your room thermostat is turned up.Ensure the main power switch to the boiler is in the ON position.
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Gas Safe Register →Ideal models that show the LED3 on PCB 37 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal LED3 on PCB 37 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