What is an auxiliary heater in a car or Webasto?

Because the car’s engine heats up quite hard at low temperatures in winter, especially diesel engines. A new heating system has been developed, that has the role to heat the engine faster and not only that.

These devices are generally from companies called Webasto, Eberspacher or Airtronic.

However, by far, the most well-known name in this field is Webasto. A German brand with its name from the one who opened the company in 1901 and its location, ie Wilhelm Baier, Stockdorf. Webasto is today the largest manufacturer of auxiliary heaters for cars and retractable car ceilings. So everything that means a Cabrio or a hatchback car nowadays has a Webasto ceiling

Today, these Webasto systems are more and more present in cars both diesel and petrol.

How does a car auxiliary heater work?

When it is cold outside, the role of an auxiliary heater is to quickly heat the engine and coolant. So, the car will heat up as soon as you get in it.

This process can be started from a remote control, so it is not necessary for the engine to be started for the auxiliary heating system to work.
Auxiliary heating systems can be both independent and parallel. The independent ones work as I said above, without the need to start the engine, and the parallel ones work when the engine is started.

Parallel auxiliary heating systems are found mainly on diesel engines, engines that are known to be very difficult to heat at low temperatures in winter. The parallel systems start together with the engine, and after the coolant reaches the optimum operating temperature, the system stops automatically.
Both parallel and independent heating systems need a maximum of 5-10 minutes to heat the antifreeze.

The auxiliary heating system uses the car’s fuel to operate. The fuel is extracted from the tank by a pump attached to the system, which sprays it on an incandescent spark plug that ignites at startup.

The incandescent spark plug causes the mixture of outside air and fuel to ignite in a housing. Outside the housing, the coolant circulates in a closed system through the engine helped by a heater pump. If it is an independent heating system, the coolant is circulated in the radiator from the air conditioner, to heat the air.

Is it worth having an auxiliary heater in the car?

Auxiliary heating is good if you are a comfortable person and you want to get in the winter directly in a heated car, with clean windows, as in the video below.

The auxiliary heating system helps the engine because after you allow the system to warm up the coolant when you turn it on automatically, the engine will not be subjected to a cold start, which is bad for your engine over time, thus decreasing its wear.

It depends especially on the places where you live. If winters there are long and the cold period lasts many months, it is worth having these heating systems installed. But if you are in an area where winter does not exist and 10 months a year temperatures are good, an auxiliary heater will not be of much help to you.

Auxiliary heaters use the car’s fuel to heat the coolant faster which, in turn, heats the engine faster. All for the passengers to benefit from increased comfort when it is cold outside.

My opinion is that it is worth investing in a Webasto or auxiliary heater if you live in a very cold area and if you have a diesel engine that heats up very slow.

Stationary heaters have a minimum fuel consumption. They need only 0.6 liters to operate a full hour at full power. At the same time, the consumption of fuel decreases, because the engine will be preheated.

You can also install an auxiliary heating system on your car if it does not have one, there are specialized workshops that do this operation very well.

Advantages of using a car auxiliary heater:

  • Increased comfort for driver and passengers.
  • Decreases engine wear.
  • The engine is already heated, so no waiting time is needed.
  • The snow and ice on the car will melt instantly.
  • You won’t find frozen doors anymore.
  • Low consumption.
  • It can be installed on most cars.
  • It does not pollute.

What risks does an auxiliary heater have?

The risks that this type of system presents are only related to reliability. There are no major risks in having an auxiliary heating system installed in your car. The heating process that this system is meant to do takes place in a safe and isolated place.

One thing to note is that, when having this system installed, the lifespan of the car battery is reduced by approximately 1 year. But this is a minor price paid for your comfort.

Common problems and symptoms for a car auxiliary heating system

  • Regarding the system reliability, the incandescent spark plug may lose its efficiency over time and, instead of eliminating clean gas on the Webasto exhaust, white smoke will come out, a sign that the spark plug burning is not correct. There may also be problems with the coolant recirculation pump, with the programming system and remote control. 
  • Internal memory errors. Usually, they do not affect the mode of operation.
  • The heater may lock due to a number of duplicate codes. If the device crashes 4 to 6 times, then the system will crash and save an error report. The heater will not unlock independently. You must contact the company’s service and diagnostic center. The heater can block because of overheating.
  • Heater errors may occur if the fuel is bad. If you fill the tank with bad fuel or fuel that does not have enough additives for winter conditions, it can cause some errors.
  • Accidental shut down due to low or high voltage. When the voltage reaches 11.5V, the mechanism stops for a while. The voltage can be measured by the control unit. When the voltage is too high, it is measured by a heater. Usually, at 16V, the voltage no longer works, it stops and cleans. If the problem is resolved, the system will work again.

You also have error codes and manual instructions with all the error codes explained. The errors can be read by connecting the auxiliary heater to a PC.

How much do car auxiliary heaters cost?

If you want to install an auxiliary heating system in your car prepare to invest a nice amount of money in this operation because they are not cheap. Costs start from approximately $1000 and can be even more expensive than $2000. This does not include the labor which is in the price range of $400 to $650


In conclusion, a Webasto or an auxiliary heater for the car is a system that has many advantages.

It is not cheap to install it on your car, and also it is not cheap to repair this system if it worns. Anyway, many specialists can repair a Webasto, which requires adjustment on the bank and on the computer, which causes many to simply disconnect it.

I will advise you not to buy one from the junkyard. But overall, a Webasto is a great deal, well thought out system that will help both the engine and the driver when extreme cold is present.

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