F01

Webasto Furnace: “F01”

warning RV furnace fault codes

Safety Repeated failed starts can flood the burner with unburned fuel. Always confirm the exhaust is clear and routed outside before retrying - unburned or partially burned diesel/petrol produces toxic exhaust including carbon monoxide. Never sniff the exhaust to test for fuel.

What it means

No start - the heater attempted ignition and, even after a repeated start attempt, no flame formed. The unit gives up and shuts down.

Most likely causes

Out of fuel or blocked/kinked fuel line, or air in the fuel line most likely
Blocked combustion air intake or exhaust outlet common
Fuel pump not delivering (electrical or mechanical fault) common
Exhaust temperature sensor fouled with deposits / failing glow plug or evaporator less common

Safe checks you can do yourself

Check the fuel tank level - many F01 faults are simply an empty or near-empty tank.
Look for kinked, leaking, or blocked fuel lines between tank and heater.
Make sure the combustion-air intake and exhaust pipe are clear of dirt, snow, or obstructions.
Listen for the fuel pump ticking during a start attempt.

How to reset / clear F01

Correct the underlying cause (refuel, clear blockage).
Switch the heater off and then on again to re-attempt a start.
If it has locked out after repeated failures, perform the fuse-pull reset (see F00/F12).

When to call a technician

If fuel and air paths are confirmed clear but the heater still will not light, or the glow plug/evaporator is suspected, have a technician check the fuel pump, glow plug and evaporator mount.

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 "F01" mean?

No start - the heater attempted ignition and, even after a repeated start attempt, no flame formed. The unit gives up and shuts down.

How do I reset Webasto Furnace F01?

Correct the underlying cause (refuel, clear blockage). Switch the heater off and then on again to re-attempt a start. If it has locked out after repeated failures, perform the fuse-pull reset (see F00/F12).

What is the most common cause of F01 on a Webasto Furnace?

The most likely cause is out of fuel or blocked/kinked fuel line, or air in the fuel line.

Related · Webasto furnace

F00
The heater's control unit (ECU) has an internal fault, the h… F02
Flame abort / flame failure - a flame was established but we… 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 01 (Butlertechnik / Webasto)
Webasto Air Top 2000 STC Fault Error Codes — Section 5.5, F01 No start (Butlertechnik / Webasto)

Note: On rotary/Multi Control elements without a display, F01 shows as one long blink pulse after the five short lead-in signals.

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