Short answer: Run your parking heater once for 15–20 minutes before winter, watch out for smoke, smells and noises, keep the tank at least a quarter full and have the battery checked. The heater should also run briefly once a month in summer. If it won’t start or switches off again, the fault memory helps to find the cause.
Most parking heaters sit idle from March to October. The first cold morning then shows whether everything works. A quick check in autumn helps you avoid unpleasant surprises.
1. Do a test run
Start the parking heater once with the ventilation running and let it run for 15–20 minutes. This shows whether it ignites reliably and keeps running. A little smoke may appear briefly after starting – that is normal, but it should clear quickly.
2. Watch out for warning signs
- Persistent white or black smoke from the heater’s exhaust
- Strong smell of diesel
- Whistling, grinding or rattling noises (often the fan)
- The heater switches off after a few minutes
If you notice any of these signs, have the unit checked before winter really sets in.
3. Don’t run the tank dry
The parking heater draws its fuel through its own line, which does not reach the bottom of the tank. In winter, keep the tank at least a quarter full, otherwise the heater won’t start.
4. Keep an eye on the battery
The parking heater draws a lot of power, especially when starting. A weak battery leads to shutdowns – and in the worst case the engine won’t start afterwards. Short trips combined with long heating times put a particular strain on the battery. Have the battery tested before winter.
5. Run it briefly in summer too
Webasto recommends running the heater for a few minutes about once a month outside the heating season as well. This keeps the fuel pump and fan moving and reduces deposits.
6. Have the fault memory read
If anything seems unusual during the test run, have the fault memory read out. Entries for flame failure, glow plug, fan or overheating show where the problem lies. If the unit has locked itself after several failed starts, the lock can also be cleared at the same time.
And if the parking heater is faulty?
It doesn’t have to be an expensive new unit. We repair Webasto heaters such as the Thermo Top C, Thermo Top C-Z and Thermo Top V at a fixed price – by post from all over Germany and the EU. If you need it quickly, reconditioned exchange units are also available for many models. Everything comes with a 12-month warranty. Shipping is free within Germany and costs €25 to other EU countries.
Frequently asked questions
How long should the parking heater run?
20–30 minutes is usually enough for a warm cabin. If you only drive a very short distance afterwards, limit the running time to protect the battery.
Is smoke when starting normal?
Brief, light smoke in the first few minutes: yes. Heavy or persistent smoke indicates a coked combustion chamber or incorrect combustion.
Which parking heater do I have?
The part number on the heater’s type plate tells you. Feel free to send us a photo or call us on +49 5671 7664710.
Go to repair: Webasto parking & auxiliary heaters – repair and exchange
