F07 Boiler Fault Code: What It Means on Every Brand

The F07 fault code appears on 3 brands — Ferroli, Johnson & Starley and Protherm — and it does not mean the same thing on each. The same two or three characters can signal a pressure problem on one boiler and an ignition fault on another, so identify your brand first and use the table below to jump to the right page.

Up to: Lockout — engineer likely 3 brands use this code Meaning differs by brand

Which brand is your boiler?

The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.

Brand	What F07 means	Severity	DIY?
FFerroli	The F07 code is a blocking fault on Ferroli boilers, meaning the boiler pauses operation but may recover automatically once the underlying condition clears. Full guide →	Engineer may be needed	No
JSJohnson & Starley	F07 on a Johnson & Starley unit reports an exhaust sensor fault: the temperature probe monitoring the flue gases has failed electrically or is returning implausible readings. Full guide →	Engineer may be needed	No
PProthermshown as F.07	The F.07 code appears on Protherm boilers when the flame monitoring system detects a problem confirming that a flame is present and stable. Full guide →	Lockout — engineer likely	No

F07 brand by brand

Ferroli F07

The F07 code is a blocking fault on Ferroli boilers, meaning the boiler pauses operation but may recover automatically once the underlying condition clears. It indicates that the air pressure switch contacts have closed earlier than expected during the startup sequence, or that flue gas temperatures have climbed too high. In plain terms, the boiler's safety system has detected that either the fan isn't creating the correct draught to safely expel combustion gases, or that the exhaust gases are running hotter than they should be. On certain Ferroli models — including the DOMIcondens HE 26C — F07 is specifically defined as a high fume temperature fault, while on other units it can relate to a pressure switch timing issue or an electronic parameter problem. It is worth knowing that if F07 triggers three times within a 24-hour period, Ferroli boilers will escalate this to an A04 lockout fault, which requires a manual reset and indicates a persistent underlying problem rather than a one-off glitch.

Causes, fixes & costs for Ferroli F07 → · All Ferroli codes

Johnson & Starley F07

F07 on a Johnson & Starley unit reports an exhaust sensor fault: the temperature probe monitoring the flue gases has failed electrically or is returning implausible readings. The exhaust sensor is a quiet but important guardian — abnormally high flue-gas temperature is an early sign of poor combustion or a fouling heat exchanger, so the controller watches it continuously and restricts operation when it loses the reading. The fault itself is usually mundane: a failed sensor element, heat-damaged wiring near the flue connection, or a corroded connector. Because it sits in the combustion-monitoring chain of a gas appliance, diagnosis and replacement are strictly a Gas Safe engineer's work.

Causes, fixes & costs for Johnson & Starley F07 → · All Johnson & Starley codes

Protherm F.07

The F.07 code appears on Protherm boilers when the flame monitoring system detects a problem confirming that a flame is present and stable. When the boiler attempts to fire, the ignition electrode produces a spark to light the burner. A separate ionisation (flame-sensing) electrode then checks that combustion is actually taking place and sends a signal back to the PCB. If that signal is absent, too weak, or inconsistent, the boiler shuts off the gas supply as a safety measure and displays F.07. On the Protherm display, the letter F flashes alongside the error number. The fault can stem from a gas supply interruption, a degraded or dirty ionisation electrode, or a fault within the main control board that prevents it from correctly reading the flame signal. The boiler also stores the ten most recent fault codes, so an engineer can review whether F.07 has been appearing repeatedly or as a one-off event.

Causes, fixes & costs for Protherm F.07 → · All Protherm codes

Frequently asked questions

Is the F07 fault code the same on every boiler?

No. F07 means different things on different brands — see the table above. Always identify your boiler's brand (it is printed on the front casing) before acting on any advice about the code.

Can I fix a F07 fault myself?

Not usually. On every brand listed, F07 points to a fault that needs a suitably registered engineer to diagnose and repair. A single reset to rule out a transient glitch is reasonable; repeated resets are not.

Who should I call about a F07 fault?

For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.

General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.