The owners of around 800,000 Mercedes vehicles are being warned to reduce the use of their vehicles to a minimum following the revelation that a coolant issue could lead to a fire. Unfortunately, the automaker does not currently possess the parts to address the problem.

Germany’s Bild newspaper first published a letter that had been sent to owners affected by the defect, which stated that “the risk of a fire could not be ruled out.” Reuters later confirmed that the letter was authentic, though it could not confirm that Bild’s quoted figure of 800,000 vehicles was correct.

According to Daimler, the issue may affect certain of the following models:

Certain C-Class (W205, 2014-2021)
CLS (C257, 2018-present)
E-Class (W213, 2017-present)
E-Class Coupe/Convertible (C/A238, 2017-present)
G-Class (W463, 1990-2018)
GLC (C/X253, 2016-present)
GLE/GLS (W/X167, 2019-present)
S-Class (W222, 2014-2020)
S-Class (W223, 2020-present)

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A Mercedes spokesperson told us that in certain models of the vehicles listed above, all fitted with diesel engines, “the coolant pump, which is controlled by vacuum, might have a leakage between the vacuum system and the coolant circuit. In this case, ingress of coolant into the vacuum system might damage various components.”

In the event that any electrical switch valves come in contact with coolant, among other potential issues, the temperature of the corresponding parts might, in isolated cases, increase over time due to an electrochemical reaction. This issue is not applicable to the U.S. market, Mercedes said.

As stated, the company does not currently have the necessary parts to solve the leak but it says that it will issue a recall as soon as it can. In the meantime, the automaker warned owners in its letter that “the affected vehicles should be driven in a particularly prudent manner and usage reduced to the bare minimum.”

Mercedes said separately that the owners of recalled vehicles should always contact their nearest Mercedes-Benz service partner as soon as possible.