Your boiler's control panel has stopped communicating with the main computer, meaning you cannot adjust settings or see what the boiler is doing.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: User interface fault
What causes this fault?
This fault occurs when the data link between the display screen and the boiler's internal computer is broken or interrupted. The most common cause is a loose connection or damaged wiring inside the unit, though a hardware failure on one of the circuit boards can also prevent the components from talking to each other.
DIY fix possible
Switch the boiler off at the main electrical fused spur switchWait for 30 secondsSwitch the power back on to see if the control screen resets and clears the error
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 F18 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Glow-worm Xtramax HE is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.