If you see that the headlights have only water vapor formed underneath and the upper surface is still very clean, then it is usually a normal condition of fogging. It is recommended to turn on the headlights frequently to dry the water vapor inside. Generally use one normally. It will disperse in about a week. (You can also turn on the headlights at idle for a long time or connect the charger and turn on the headlights)
For the cleaning work in the engine compartment, you should wipe it with a cloth or use high-pressure air to avoid “moisture wading” in the engine part as much as possible.
If the water accumulation inside the headlight is serious, disassemble it, open the lampshade, and after drying, check the surface of the headlight for damage or possible leakage. If no abnormality is found, it is recommended to replace the headlight. Back cover sealing strip and vent pipe.