306 V Emergency
Your boiler is still detecting a flame even after it has tried to shut off the gas, which is a safety conflict that requires a professional inspection.
Technical description: Flame signal after closing the fuel supply – the air/gas ratio control valve might need replacing
Typical repair cost: £220-£450 (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 306 V — 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
- Gas valve
- Ionisation electrode
- Control PCB
*Affiliate links — we may earn a commission at no extra cost to you.