What Causes Cracks in Car Headlights?

[StSteven]

Car headlight cracks can be attributed to the following reasons: Aging due to prolonged use: Fine cracks in car headlights may result from aging over time. Modern car headlight covers are made of plastic, and prolonged exposure to wind and sunlight can lead to fine cracks. These are typically repaired through a polishing and restoration process. Scratches on the car headlights: Fine cracks in car headlights could also be caused by scratches. Repairing headlight scratches requires professional technicians at auto detailing shops using specialized products. The process usually involves polishing and restoration to restore smoothness and evenness as much as possible. However, severe physical damage may not be successfully repaired through detailing.

[DelKing]

I just experienced this issue with my car's headlights being completely cracked. It mainly started when a stone hit them on the highway, leaving a dent. At first, I didn't pay much attention, but then I washed the car with hot water directly spraying the heated headlight covers, and the sudden temperature difference caused them to crack. Plastic materials are prone to becoming brittle under thermal shock, especially in older cars where the outer shell has aged and weakened over time, making it unable to withstand such stress. Long-term exposure to UV rays also accelerated the deterioration, turning the covers yellow and cracked, which allowed water to seep in and risked short-circuiting the bulbs. Later, I replaced the headlights and took the opportunity to remind everyone to use lukewarm water when washing their cars—don’t try to save money by spraying hot water on the headlights. Also, fix minor damages promptly to prevent them from spreading into bigger problems.

[DelJaxson]

This is a common issue in winter. Once I went out early in the morning and found the headlight cover cracked. Looking back, I had washed the car the night before with scalding hot water directly poured on it—thermal expansion and contraction caused immediate cracks. Stones hitting the cover are also common; small chips can turn into larger cracks due to vibration at high speeds. Over time, materials naturally age, and plastic becomes brittle, making it prone to damage. It's recommended to let the lights cool before washing the car or choose a professional car wash that uses warm water. Park in the shade to prevent UV rays from accelerating aging. If you notice small cracks, applying some sealant can prevent worsening, saving both money and hassle.

[SanGemma]

Headlight cracks should be dealt with immediately. Water ingress can cause bulb short circuits, making night driving dangerously unclear. My neighbor once hit a guardrail in the rain due to poor visibility from this issue. Common causes include impacts, temperature shocks from car washes, and material aging. Safety first—don't delay.