Vaillant error codes
Common Vaillant combi boiler fault codes and what they mean.
- F.0 Flow temperature sensor interrupted
- F.1 Return temperature sensor interrupted
- F.10 Flow temperature sensor short-circuited
- F.11 Return temperature sensor short-circuited
- F.12 Hot water temperature sensor short-circuited
- F.20 Safety thermal cut-out has operated
- F.22 Low water pressure in the system
- F.23 Temperature difference between flow and return too great
- F.24 Temperature rising too quickly
- F.25 Flue gas temperature too high
- F.27 Flame signal detected while the burner is off
- F.28 No flame detected during ignition
- F.29 Re-ignition after flame loss was unsuccessful
- F.32 Fan fault
- F.35 Air/flue pipe blocked
- F.52 Mass flow sensor fault
- F.53 Combustion regulation fault
- F.54 Fault in the gas supply
- F.57 Boiler not burning correctly in comfort mode
- F.62 Flame switch-off detected after a delay
- F.70 Device specific number (DSN) incorrect or missing
- F.72 Invalid temperature difference between flow and return sensors
- F.75 Pressure change too low when the pump starts
- F.83 Little or no temperature rise when the burner starts
- F.84 Flow and return sensor readings are implausible
- F.88 Electrical connection to the gas valve interrupted