The F67 fault code appears on 6 brands — Ferroli, Glow-worm, Heatline, Protherm, Saunier Duval and Vaillant — 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.
The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.
F67 brand by brand
The F67 code on a Ferroli boiler indicates that a Boiler Chip Card (BCC) service key is detected as connected to the PCB. In Ferroli's fault classification system, codes prefixed with 'F' are blocking faults — they may resolve on their own once the underlying condition is cleared, rather than requiring a manual reset like an 'A'-series lockout code. In practical terms, F67 is the boiler telling you that the BCC service key is present or being read; the closely related code F68 (or A68) takes this a step further and signals an actual error loading the BCC service key file. If you're seeing F67, the electronics have detected something connected to the board that is causing the boiler to pause. Note that code meanings can vary slightly between Ferroli model ranges including the Modena, Bluehelix, Optimax, and i-Series — always cross-reference with your specific model's manual if in doubt.
Causes, fixes & costs for Ferroli F67 → · All Ferroli codes
The F67 fault code on a Glow-Worm boiler points to a problem with the main printed circuit board (PCB) — the central control unit that coordinates every component in your boiler, from the ignition sequence through to the pump, fan, and gas valve. When the PCB detects an internal fault or loses reliable communication with connected parts, it triggers a lockout and displays F67 to prevent unsafe operation. Note that F67 sits within a family of related PCB fault codes (F61–F67) on Glow-Worm boilers; while they all point broadly to the main board, each sub-code can indicate a slightly different aspect of the failure, so always tell your engineer the exact code shown on the display. Because the PCB is the brain of the boiler, this fault will typically prevent heating and hot water until the underlying issue is resolved. A Gas Safe registered engineer is required to diagnose and repair this fault — it is not suitable for DIY intervention.
Causes, fixes & costs for Glow-worm F67 → · All Glow-worm codes
The F67 code on a Heatline boiler indicates that the boiler's control board has detected an abnormal or absent flame signal during the ignition sequence. Heatline is part of the Vaillant Group and shares the same underlying technology platform, so F67 carries identical meaning across both brands. The flame monitoring circuit expects a clean electrical signal — typically either 0V or 5V — to confirm whether a flame is present or absent. When the signal falls somewhere unexpected between those two values, or is missing entirely, the boiler cannot verify safe ignition and shuts down as a precaution. The result is a complete loss of heating and hot water until the underlying cause is identified and resolved.
Causes, fixes & costs for Heatline F67 → · All Heatline codes
The F.67 code appears when the boiler's control electronics receive a flame signal that is absent, unreadable, or doesn't make sense — often described internally as an implausible or irregular ionisation signal from the ASIC (Application-Specific Integrated Circuit) chip on the main board. In plain terms, the boiler cannot confirm whether a flame is present or not, so it shuts down as a safety precaution. This fault sits at the intersection of the flame-detection system and the main PCB, meaning the root cause could be a dirty or faulty ionisation electrode, damaged wiring, or a failing control board. Because the boiler has locked out to protect itself and the property, the fault will need to be properly diagnosed before the appliance can run reliably again.
Causes, fixes & costs for Protherm F.67 → · All Protherm codes
The F.67 fault code appears on Saunier Duval boilers when the main PCB (printed circuit board) is not receiving a valid flame signal during or after the ignition sequence. In straightforward terms, the boiler attempts to light, but its control board either sees no flame signal at all, or the signal it receives is too weak or erratic to confirm a stable flame is present. As a safety response, the boiler locks out to prevent unburned gas from building up. Saunier Duval shares its boiler platform and fault-code architecture with Vaillant (both are part of the same group), so F.67 carries an identical meaning on Vaillant appliances. The most common culprits are a faulty ionisation (flame-sensing) electrode and PCB-related issues such as loose connections, water ingress, or a damaged board. A professional diagnosis is always needed because the fault sits squarely within the electrical and gas-detection side of the appliance.
Causes, fixes & costs for Saunier Duval F.67 → · All Saunier Duval codes
The F.67 code appears on Vaillant boilers when the control board receives a flame signal that falls outside the expected range — in other words, the boiler's flame detection circuitry is reporting something that doesn't add up. The boiler can't confirm a stable, genuine flame during ignition, so it shuts itself down as a precaution. In practice this means no heating and no hot water. You may notice the boiler attempting to fire two or three times before locking out and displaying F.67. Although there is no immediate safety emergency, the fault does need proper investigation because it often points to a failing electronic component, moisture ingress, or a wiring problem rather than anything the boiler can recover from on its own.
Causes, fixes & costs for Vaillant F.67 → · All Vaillant codes
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.
