BoilerFaultCodesYour boiler is simply reminding you that its annual service is due soon; it is a notification rather than a breakdown.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Service timer function
What causes this fault?
This notification is triggered by an internal clock within the boiler’s control board that tracks the time elapsed since its last professional maintenance check. It is not caused by a mechanical failure or a parts breakdown, but rather a pre-set countdown reaching its limit. Once the timer completes, the display shows this code to prompt you to book a Gas Safe engineer.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like SE — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.