F.67 Burner in a fault state Ionisation current lies out- side the permissible range Check gas supply (gas pressure and gas flow switch), check gas solenoid valve and inlet strainer
The F67 error code on Viessmann boilers indicates f.67 burner in a fault state ionisation current lies out- side the permissible range check gas supply (gas pressure and gas flow switch), check gas solenoid valve and inlet strainer.
Viessmann F67 means: f.67 burner in a fault state ionisation current lies out- side the permissible range check gas supply (gas pressure and gas flow switch), check gas solenoid valve and inlet strainer. The usual causes are gas valve coil failure (electrical fault), gas valve stuck closed or partially open or gas supply interrupted (prepayment meter, emergency control valve). A Gas Safe registered engineer should diagnose the root cause.
What Does F67 Mean
The F67 code is shown by the boiler’s control board when it detects f.67 burner in a fault state ionisation current lies out- side the permissible range check gas supply (gas pressure and gas flow switch), check gas solenoid valve and inlet strainer. The boiler then stops instead of continuing to run in that condition: the code is the appliance reporting a problem, not proof that the boiler is broken.
| What you see on the boiler |
|---|
| The display shows F67 and the boiler stops until the fault is cleared |
Common Causes
Causes documented in 4 technical sources.
| Cause |
|---|
| Gas valve coil failure (electrical fault) |
| gas valve stuck closed or partially open |
| gas supply interrupted (prepayment meter, emergency control valve) |
| incorrect gas pressure (too high or too low) |
| gas valve wiring fault |
| PCB not sending open signal to the gas valve |
Safety Warning
F67 is a gas-related fault. Never attempt to repair or adjust the gas valve, burner assembly, or flue system yourself. All gas work must be carried out by a Gas Safe registered engineer (UK) or licensed HVAC technician (US). Repeated resets after ignition failure can cause unburnt gas to accumulate inside the combustion chamber — this is a serious safety hazard. If you smell gas at any point, turn off the gas supply at the meter, open windows, leave the property, and call your gas emergency service immediately. Warning: this fault code may relate to gas supply, flue or combustion issues. Do not attempt repair — contact a Gas Safe registered engineer immediately.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
Step-by-Step Diagnosis
67 Burner in a fault state Ionisation current lies out- side the permissible range Check gas supply (gas pressure and gas flow switch), check gas solenoid valve and inlet strainer
How to Fix It
Restore the gas supply if interrupted
replace the gas valve if it is stuck or electrically faulty — Gas Safe registered engineer only
adjust gas pressure if out of specification
repair wiring between gas valve and PCB
if PCB is not sending signal, replace the PCB. Warning: never attempt gas work unless you are Gas Safe registered
Refer to the Viessmann service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
Diagnostic Tools
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Affected Models
Viessmann models that can display fault code F67:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Viessmann models | — | Possible |
Frequently Asked Questions
Restore the gas supply if interrupted. According to the technical documentation, this is the first check on the list for F67.
F67 is classified as a high-severity fault: it involves gas, combustion or flue components. Do not keep resetting the boiler and do not attempt the repair yourself — call a Gas Safe registered engineer.