BoilerFaultCodesYour boiler is failing to detect a flame, which prevents it from heating up even if it seems to be trying to start.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: No or insufficient ionisation flow
What causes this fault?
This fault occurs when the boiler's internal sensor fails to confirm that a flame has successfully ignited. The most common reasons include a worn-out ignition spark, a blockage in the gas supply, or a dirty sensor that can no longer 'see' the heat produced by the burner.
This issue often surfaces during the first cold snap of autumn when the boiler is forced to work harder after sitting idle through the summer months.
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 F007 — 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.