What do Vaillant boiler error codes mean?
Vaillant boilers display fault codes starting with F (fault) or S (status). The most common are F22 (low pressure), F28 (ignition failure) and F75 (pressure sensor fault).
What Do Vaillant Boiler Error Codes Mean?
Vaillant boilers display fault codes when a problem is detected. These appear on the boiler display — usually starting with F (fault) or S (status/information).
Most Common Vaillant Error Codes
| Code | Meaning | DIY Fix? | |------|---------|----------| | F22 | Low water pressure | Re-pressurise to 1–1.5 bar | | F23 | Pump circulation fault | Engineer required | | F24 | Pump overrun / temperature fault | Engineer required | | F28 | Ignition failure | Check gas supply; engineer if persists | | F29 | Flame loss | Engineer required | | F62 | Gas valve fault | Engineer required | | F75 | Pressure sensor/pump fault | Engineer required | | F83 | Flow/return sensor fault | Engineer required |
F22 — What to Do
- Locate the pressure gauge (should read 1–1.5 bar when cold)
- If below 1 bar, use the filling loop to re-pressurise
- Open both filling loop valves slowly, watch the gauge, close at 1.2 bar
- If pressure drops repeatedly, call an engineer — there's a leak
F75 — Common in London
The F75 code is particularly common in London due to hard water. It often indicates a failing pressure sensor or pump. This requires a Gas Safe engineer.
For all Vaillant fault codes, see our full boiler error codes guide or call 020 7458 4949.
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