BoilerFaultCodesYour boiler's internal computer has lost communication with its electronic components and needs a professional reset or repair.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Main board connection fault
What causes this fault?
This fault occurs when the boiler's main control centre can no longer send or receive signals from its internal components, causing the system to freeze up for safety. The most common reason is a physical breakdown of the circuitry on the main board or a loose connection in the wiring that links the components together.
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 F13 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
Affiliate links — we may earn a commission at no extra cost to you.