--- title: Webasto Air Top 2000 STC Air Heater Fault Codes description: This guide will assist you in identifying the cause of a fault, should one occur in the Webasto Air Top 2000 STC Air Heater fitted to your CamperKing campervan --- [Skip to content](https://guides.camperking.co.uk/webasto-airtop-2000-stc-fault-code-finder#main-content) [![CamperKing Logo](https://guides.camperking.co.uk/hubfs/camperking-horizontal-white-rgb.svg)](https://guides.camperking.co.uk/?hsLang=en) - [Main site](https://www.camperking.co.uk/) - [Blogs](https://blog.camperking.co.uk/) - [Guides](https://guides.camperking.co.uk/) Open main navigation Close main navigation - [Main site](https://www.camperking.co.uk/) - [Blogs](https://blog.camperking.co.uk/) - [Guides](https://guides.camperking.co.uk/) - [Go to camperking.co.uk](https://www.camperking.co.uk/) [Go to camperking.co.uk](https://www.camperking.co.uk/) Welcome to CamperKing Guides. 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[Diesel heater guides](https://guides.camperking.co.uk/owners-guide?hsLang=en#diesel-heater-guides) # Webasto Air Top 2000 STC Air Heater Fault Codes ## This guide will assist you in identifying the cause of a fault, should one occur in the Webasto Air Top 2000 STC Air Heater fitted to your CamperKing campervan | **Fault Code** | **Fault Message** | **Fault Details** | **Recommended Measures** | | --- | --- | --- | --- | | 00 | No error | No error | No action necessary | | 01 | Defective control unit | Defective control unit, wrong end-of-line programming or coolant temperature sensor (at water heaters) failure | Replace control unit | | 02 | No start | After start-up has been repeated, combustion still fails to occur | 1) Check for faults in the air intake and exhaust systems 2\) Check for faults in fuel system 3\) Check the fuel pump 4\) Electrical check of glow plug | | 03 | Flame failure | The flame went out during operation and combustion | See error 02 | | 04 | Supply Voltage too high | The supply voltage was too long above the maximum threshold value | Check system voltage | | 05 | The flame was detected prior to combustion | Flame detector signals flame before combustion operation | 1) Check for fault in the air intake, exhaust systems 2\) Check for faults in the fuel system 3\) Check the fuel pump 4\) Electrical check of glow plug | | 06 | Heating unit overheated | Overheat protection has been activated or the temperature at the the heat exchanger has exceeded the upper limit | 1) Check for fault in air intake/blowout side, exhaust systems 2\) Check for faults in the fuel system | | 07 | Heater lock-out | Heater interlocked | 1) Reset heater lock-out and attempt restart 2\) Read out further fault messages and work through instructions Reset heater lock-out: switch on the heater. Pull fuse F1 for at least 10 s. Switch off the heater. Reinsert fuse F1. Switch on the heater. NOTE The following fault occurred several times: Fault counter: \> 10x False start counter: \> 7x Overheating counter: \> 20x | | 08 | Fuel pump short circuit | The fuel pump has a short circuit to ground | Electrical check of fuel system | | 09 | Combustion air fan short circuit | The combustion air fan has short circuit to ground | Electrical check of combustion air fan motor | | 11 | Wrong fuel coding | Incorrect parameter block or wrong heater (diesel/gasoline) used | Replace control unit | | 12 | W-bus communication failure | W-bus communication failure | 1) Check for fault in area of W-bus communication/W-bus control element/W-bus Telestart 2\) Replace control unit | | 14 | Temperature sensor short circuit (internal, external) | The temperature sensor has short circuit to ground | Electrical check of external/internal temperature sensor | | 15 | Combustion air fan blocked | Combustion air fan blocked | 1) Check for fault in fan motor 2\) Heating air intake fan wheel snagging or jammed 3\) Combustion air intake fan wheel snagging or jammed | | 17 | Gradient exceedance overheat protection | The temperature rise at the heat exchanger has exceeded the upper limit. | Check for fault in air intake/blowout side, exhaust systems | | 18 | Communication failure on customer-specific bus | Communication failure on customer specific bus | - | | 19 | Glow plug/flame monitor short circuit | Glow plug / electronic ignition unit has a short circuit to ground | Electrical check of glow plug | | 81 | EOL checksum error | The checksum of EOL dataset is wrong | Replace control unit | | 82 | No start during test-run | No start during test-run | See error 02 | | 83 | Flame failure | Flame interruption during combustion operation, more than FAZ (EEPROM) times. | See error 02 | | 84 | Operating voltage too low | The supply voltage was too long below maximum threshold value | Check system voltage | | 88 | Fuel pump interruption | Fuel pump interrupted or short circuit to supply voltage UB | Electrical check of fuel system | | 89 | Combustion air fan interruption | Combustion air fan interrupted or short circuit to supply voltage UB | Electrical check of fan motor | | 91 | Wrong control unit coding | Control unit locked or coded as neutral | Replace control unit | | 92 | Command refresh failure | Command refresh failure | Check for fault in the area of W-bus communication/W-bus control element/W-bus Telestart | | 94 | Temperature sensor interruption (internal, external) | Temperature sensor interrupted or short circuit to supply voltage UB | Electrical check of external/internal temperature sensor | | 97 | Gradient undershooting during start | Overheat sensor position wrong (temperature gradient too low) | 1) Check position of overheating sensor 2\) Check fuel supply system | | 99 | Glow plug / electronic ignition unit interruption | Glow plug / electronic ignition unit interrupted or short circuit to supply voltage UB | Electrical check of glow plug | | 0 A | Glow plug/flame monitor short circuit | Glow plug/Flame monitor circuit has a short circuit to ground | Electrical check of glow plug | | 1 A | Flame sensor short circuit | The flame sensor has a short circuit to ground | Electrical check of flame monitor | | 1B | Overheat sensor short circuit | The overheat sensor has a short circuit to ground | Electrical check of overheating sensor | | 8 A | Glow plug / electronic ignition unit interruption | Glow plug/Flame monitor interrupted or short circuit to supply voltage UB | Electrical check of glow plug | | 9 A | Flame sensor interruption | Flame sensor interrupted or short circuit to supply voltage UB | Electrical check of flame monitor | | 9B | Setpoint potentiometer interruption | Setpoint potentiometer interrupted or short circuit to supply voltage UB | Electrical check of setpoint sensor | | AB | Overheat sensor interruption | Overheat sensor interrupted or short circuit to supply voltage UB | Electrical check of overheating sensor | | F00 | Defective control unit | Control unit defective EOL programming error | 1) Check for fault in area of the W-bus communication/W-bus control element/W-bus Telestart 2\) Replace the control unit | | F01 | No start | No flame formed even after a repeated start attempt | 1) Check for faults in air intake and exhaust systems 2\) Check for faults in fuel system 3\) Check the fuel pump 4\) Electrical check of glow plug | | F02 | Flame failure | The flame goes out during operation and no longer reformed after a restart attempt. | See error 01 | | F03 | Supply Voltage too high | The operating voltage was higher than the maximum permissible value for too long | Check system voltage | | F04 | The flame was detected prior to combustion | The flame monitor detected a flame before combustion started | 1) Check for fault in air intake, exhaust systems 2\) Check for fault in fuel system 3\) Check fuel pump 4\) Electrical check of glow plug | | F05 | Flame sensor interruption | There is a break or short to UB in the electrical circuit of the flame detector | Electrical check of flame monitor | | F06 | Temperature sensor interruption (internal, external) | There is a break or short to UB in the temperature sensor | Electrical check of external/internal temperature sensor | | F07 | Fuel pump interruption | There is a break or short to UB in the electrical circuit of the fuel pump | Electrical check of fuel system | | F08 | Combustion air fan short circuit | The combustion air fan has a short to the ground or the fan motor is overloaded | Electrical check of combustion air fan motor | | F08 | Combustion air fan blocked | Combustion air fan blocking guard has tripped | 1) Check for fault in fan motor 2\) Heating air intake fan wheel snagging or jammed 3\) Combustion air intake fan wheel snagging or jammed | | F09 | Glow plug / electronic ignition unit interruption | There is a break or short to UB in the glow plug/ignition spark generator | Electrical check of glow plug | | F10 | Heating unit overheated | Overheating lock-out has tripped (heater overheated) | 1) Check for fault in air intake/blowout side, exhaust systems 2\) Check for fault in fuel system | | F11 | Overheat sensor interruption | There is a break or short to UB in the electrical circuit of the overheating sensor | Electrical check of overheating sensor | | F12 | Heater lock-out | Heater lock-out was activated | 1) Reset heater lock-out and attempt restart 2\) Read out further fault messages and work through instructions Reset heater lock-out: switch on heater. Pull fuse F1 for at least 10 s. Switch off heater. Reinsert fuse F1. Switch on the heater. NOTE The following fault occurred several times: Fault counter: \> 10x False start counter: \> 7x Overheating counter: \> 20x | | F14 | Gradient undershooting during start | Wrong position of overheating sensor (overheating sensor gradient too small) | 1) Check the position of overheating sensor 2\) Check the fuel supply system | | F15 | Setpoint potentiometer interruption | There is a break or short to UB in the electrical circuit of the setpoint potentiometer | Electrical check of setpoint sensor |   - [Owners Guide](https://guides.camperking.co.uk/owners-guide?hsLang=en#main-content) - [Operating Instructions](https://guides.camperking.co.uk/owners-guide?hsLang=en#operating-instructions) - [Diesel heater guides](https://guides.camperking.co.uk/owners-guide?hsLang=en#diesel-heater-guides) - [Awning guides](https://guides.camperking.co.uk/owners-guide?hsLang=en#awning-guides) - [Leisure battery guides](https://guides.camperking.co.uk/owners-guide?hsLang=en#leisure-battery-guides) - [Care and maintenance guides](https://guides.camperking.co.uk/owners-guide?hsLang=en#care-and-maintenance-guides) - [Useful guides](https://guides.camperking.co.uk/owners-guide?hsLang=en#useful-guides) - [Accessory guides](https://guides.camperking.co.uk/owners-guide?hsLang=en#accessory-guides) - [Buyers Guide](https://guides.camperking.co.uk/buyers-guide?hsLang=en#main-content) - [Base van guides](https://guides.camperking.co.uk/buyers-guide?hsLang=en#base-van-guides) - [Conversion guides](https://guides.camperking.co.uk/buyers-guide?hsLang=en#conversion-guides) - [Finance guides](https://guides.camperking.co.uk/buyers-guide?hsLang=en#finance-guides) - [CamperKing FAQ](https://guides.camperking.co.uk/camperking-faq?hsLang=en#main-content) - [Sales guide](https://guides.camperking.co.uk/camperking-faq?hsLang=en#sales-guide) - [Main site](https://www.camperking.co.uk/) - [Blogs](https://blog.camperking.co.uk/) - [Guides](https://guides.camperking.co.uk/) [![camperking-badge-vintage-red-rgb](https://guides.camperking.co.uk/hubfs/camperking-badge-vintage-red-rgb.svg "camperking-badge-vintage-red-rgb")](https://camperking.co.uk)   [mailto:info@camperking.co.uk](mailto:info@camperking.co.uk) Copyright © 2025, CamperKing