Webasto Furnace: “F14”
warning RV furnace fault codes
What it means
On the Air Top EVO 40/55: the blow-out (warm-air outlet) temperature sensor circuit has a short or open circuit. On the Air Top 2000 STC: 'gradient undershoot during start' - the overheat sensor is mis-positioned or reads too small a temperature rise.
Most likely causes
- EVO: short or open circuit in the blow-out temperature sensor or wiring common
- 2000 STC: overheat sensor wrongly positioned (temperature gradient too low) common
- 2000 STC: fuel supply problem causing slow temperature rise less common
Safe checks you can do yourself
- Inspect the relevant temperature-sensor wiring and connector for damage.
- On the 2000 STC, check fuel supply and that the overheat sensor is correctly seated.
How to reset / clear F14
- Correct the wiring or sensor-position fault.
- Switch the heater off and on; clear a lock-out with the fuse-pull reset if needed.
When to call a technician
If wiring and sensor position are correct but the fault persists, have the sensor tested and replaced by a technician.
Applies to
Air Top EVO 40 · Air Top EVO 40 B (petrol) · Air Top EVO 40 D (diesel) · Air Top EVO 55 · Air Top 2000 STC
FAQ
What does Webasto Furnace code "F14" mean?
On the Air Top EVO 40/55: the blow-out (warm-air outlet) temperature sensor circuit has a short or open circuit. On the Air Top 2000 STC: 'gradient undershoot during start' - the overheat sensor is mis-positioned or reads too small a temperature rise.
How do I reset Webasto Furnace F14?
Correct the wiring or sensor-position fault. Switch the heater off and on; clear a lock-out with the fuse-pull reset if needed.
What is the most common cause of F14 on a Webasto Furnace?
The most likely cause is evo: short or open circuit in the blow-out temperature sensor or wiring.
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Sources
- Air Top Evo 40 / Air Top Evo 55 - Fault Codes / Troubleshooting (Fig. 503) — Section 5.4, Fault code F 14 (PC codes 1B short / AB open, blow-out sensor) (Butlertechnik / Webasto)
- Webasto Air Top 2000 STC Fault Error Codes — Section 5.5, F14 Gradient undershooting during start (Butlertechnik / Webasto)
Note: F14 has a DIFFERENT meaning between the two model families: blow-out sensor fault on EVO 40/55 vs start-gradient undershoot on the 2000 STC. Both are documented; treat the meaning per your specific heater.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.