F9 High
Your boiler’s internal computer brain hasn't been programmed correctly, meaning it doesn't know which model it is and cannot start up.
Technical description: Unconfigured printed circuit board (PCB)
Typical repair cost: £100-350 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Protect yourself from future repair bills
A boiler cover plan would cover faults like F9 — no call-out fees, no surprises.
*Affiliate links — we may earn a commission at no extra cost to you. Prices shown are starting prices.
Parts commonly replaced
- Printed Circuit Board (PCB)
- PCB Data Chip
*Affiliate links — we may earn a commission at no extra cost to you.