Is It Normal for Mercedes-Benz Headlights to Fog Up?
2 Answers
Mercedes-Benz headlights fogging up is normal. This is because there is a ventilation and heat-dissipating rubber tube at the rear cover of the headlight structure, and the moisture in the air enters the headlight through this rubber tube, attaching to the lens and creating fog. Reasons for Mercedes-Benz headlights fogging up: Mercedes-Benz headlights adopt a non-sealed design for heat dissipation. There is an intake hole and an exhaust hole on the headlight, which are used to balance the air temperature inside the headlight. The exhaust hole expels hot air, while the intake hole draws in cold air from outside. When the outside air is humid (such as during rain or snow), the air drawn in contains relatively high moisture. After turning off the headlights, the temperature inside the headlight drops, causing the drawn-in air to condense into fog. Methods to deal with headlight fogging: First, keep the engine idling, then open the engine hood, unscrew the dust cover or dust cap, and keep the headlights on for about 30 minutes. Then use an air spray gun to increase the airflow speed inside the lens until the moisture and fog are removed. At the same time, be sure to locate any areas with poor sealing, clean and dry them thoroughly, and reseal them. Alternatively, you can choose to go to a repair shop for defogging.
Just the other day, a Mercedes-Benz GLC owner came in to fix his headlights, saying he noticed fog inside the lens after washing the car. Actually, it depends on the situation: if fog appears after highway driving or driving in the rain, it usually dissipates on its own within ten minutes. Every Mercedes headlight is designed with a vent hole, so a small amount of moisture is quite normal. But if it hasn't cleared after three days of parking, or if the fog condenses into water droplets that run down, then it's likely due to aging seals or cracks in the lamp housing, especially common in older vehicles. Some brand-new cars that develop severe fogging right after delivery are definitely suffering from assembly quality issues. The official Mercedes manual actually states that minor fogging isn't considered a fault, but if it causes blurred lighting or water accumulation inside the housing, you're absolutely entitled to claim compensation. Last year, our shop helped a customer replace two complete headlight assemblies for this very reason.
