Vokera Vibe fault AF2
DHW anti-freeze protection active
Gas boilerWhat it means
Protective status (not a fault lockout) shown when DHW anti-freeze function activates because domestic hot water probe temperature drops below 5°C. Burner ignites at minimum output, maintained until delivery water temperature reaches 55°C.
Likely causes
- DHW probe temperature dropped below 5°C due to low ambient temperature or boiler being off
- DHW probe temperature below 5°C while boiler in OFF status with electrical and fuel supply active
- Damaged or worn burner insulating panel
Where to start
- Verify DHW probe temperature reading
- Confirm burner ignites at minimum output during this condition
- Remove the burner insulating panel (D) by inserting a blade underneath the surface
The full answer, free
- 17 more checks in order
- The readings and component tests from the manual
- How to put it right, step by step
- The manual page for this fault (page 29), right under the answer
Safety: Isolate gas and power before you open the case. If you have been into the gas side, do a tightness test, and a combustion and flue check before you hand back. Gas Safe (UK) or RGI (Ireland) work only.
From the Vokera manual for the Vibe. Check the model on the data plate before you order parts.
Other Vokera Vibe fault codes
- A10Flame lockout / condensate drain obstructed / flue gas exhaust/air suction obstructed
- A30Fan fault
- A40Fill the system
- A41Fill the system (transitional)
- A59High power supply voltage
- A60DHW probe fault
- A70Flow sensor fault / flow sensor overtemperature / flow/return sensor differential
- A80Return probe fault / return probe overtemperature / return-flow sensor differential
- A90Flue gas probe fault
- A91Reset operating hours counter (related to fault A91)
- AF1Heating anti-freeze protection active
- CFSService call signal / periodic boiler control
- E091Heat exchanger cleaning required (unusual usage threshold)
- SFSSTOP FOR SERVICE (permanent inhibition)