F02

Webasto Furnace: “F02”

warning RV furnace fault codes

Safety A flame that repeatedly dies mid-cycle can leave unburned fuel and produce dangerous exhaust. Ensure the exhaust is fully sealed and vented outdoors. With petrol (gasoline) units, fuel vapor is highly flammable - keep ignition sources away when inspecting lines.

What it means

Flame abort / flame failure - a flame was established but went out during operation and did not re-establish after a restart attempt.

Most likely causes

Fuel supply interruption: low fuel, blocked line, or air in the fuel system most likely
Partially blocked combustion air or exhaust path common
Fouled exhaust temperature sensor or worn evaporator less common

Safe checks you can do yourself

Check fuel level and lines for blockage or leaks.
Inspect intake and exhaust for partial obstruction.
Note whether the flame-out happens at a particular point in the cycle.

How to reset / clear F02

Address the fuel/air cause.
Switch the heater off and back on to restart.
Clear any resulting lock-out via the fuse-pull procedure if needed.

When to call a technician

If fuel delivery and air paths are good but the flame keeps failing, have a technician check the exhaust temperature sensor and evaporator.

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 "F02" mean?

Flame abort / flame failure - a flame was established but went out during operation and did not re-establish after a restart attempt.

How do I reset Webasto Furnace F02?

Address the fuel/air cause. Switch the heater off and back on to restart. Clear any resulting lock-out via the fuse-pull procedure if needed.

What is the most common cause of F02 on a Webasto Furnace?

The most likely cause is fuel supply interruption: low fuel, blocked line, or air in the fuel system.

Related · Webasto furnace

F00
The heater's control unit (ECU) has an internal fault, the h… F01
No start - the heater attempted ignition and, even after a r… F03
Supply voltage out of range - the heater's operating voltage… F04
Premature flame detection - the flame/exhaust temperature mo… F07
Fuel pump fault - the dosing/fuel pump circuit shows an open… F08
Drive/combustion-air motor fault - the fan motor has an open…

Sources

Air Top Evo 40 / Air Top Evo 55 - Fault Codes / Troubleshooting (Fig. 503) — Section 5.4, Fault code F 02 (Butlertechnik / Webasto)
Webasto Air Top 2000 STC Fault Error Codes — Section 5.5, F02 Flame failure (Butlertechnik / Webasto)

Note: On the 2000 STC the same flame-failure condition is also logged in hex as 03 / 83.

● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.