Fogged headlight – is there always a fault?

“Foggy” steam car headlights are associated with rather worn-out vehicles, in which the seal has long ceased to fulfill its role. Meanwhile, this phenomenon can also be found in new cars – often even with the so-called top shelf.


Many readers of this text will be surprised to see that the headlights installed in cars are not (because they cannot be) hermetically sealed. Why? The answer is both operational and security considerations. Both halogen bulbs and xenon burners produce a lot of heat when lit. It is drained through special ventilation gaps that prevent overheating of the interior of the headlights and their shades. Unfortunately, the same slits cause the penetration of external moisture into the headlights, which causes them to fog. This is especially evident in the summer season after washing the car in a car wash, despite the fact that the ambient temperature is still high. This is due to the differences in temperature and humidity inside the lampshades compared to the surroundings. The fogging on the inside of the headlight shades usually disappears after driving a few kilometers due to proper air circulation inside them.

However, if we observe moisture condensing inside one of the headlights or in extreme cases noticeable standing water, then we can definitely say that the diffuser or car headlight housing has been damaged. The causes of the damage may be different: from, for example, a point impact of a stone thrown from under the wheels of another vehicle on the road, to unprofessional accident repair after the so-called “Cullet”.

And here the bad news for all motorists who have had to deal with this problem: professionals strongly advise against attempts to dry the headlights and reassemble them – damaged ones should be replaced with new ones. Despite all efforts, they cannot be properly sealed. If only one headlight is damaged, it should not be changed individually. Installing a new one next to the one used so far causes a difference in the quality and intensity of road illumination, which may result in deterioration of driving safety. Therefore, always replace the headlights in pairs. When deciding to buy them, you should also compare the technical parameters in such a way that the lamps are used in accordance with the factory-fitted ones. TEAM

Audi maniac, owner of and big fan of Audi cars. Maps, firmware, car audio installer
Notify of

Inline Feedbacks
View all comments