BoilerFaultCodesYour boiler’s internal computer has developed an electronic fault, preventing the system from running safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Main PCB fault
What causes this fault?
This fault occurs when the boiler's main control board suffers an internal electronic failure, meaning it can no longer process data or send signals to other components. The most common reasons for this are general wear and tear of the electrical circuits over time or damage caused by a power surge in the home.
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 F65 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Glow-worm Flexicom 18sx 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.