F4 High

Heatline F4 Fault Code

The Heatline F4 fault code means: your boiler has failed to start the flame needed to heat your home or water, often because internal waste pipes are clogged or the ignition system isn't sparking correctly.. It appears on 6 Heatline models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Lockout due to ignition problem or Condensate Trap Blockage
Typical repair cost £120-250 (including labour)

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 →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like F4: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Heatline models that show the F4 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Heatline F4 fault code information on this page is sourced and cross-checked against the official Heatline service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026