What Causes Daytime Running Lights to Turn Yellow?
2 Answers
Daytime running lights turn yellow due to prolonged exposure to air, high temperatures, UV rays, and oxidation, which cause the headlight covers to age, resulting in yellowing and cracking. Here are some maintenance tips for car headlights: 1. Replacement: Ensure the headlights maintain good sealing, especially to prevent contamination and damage to the reflector coating. When replacing bulbs or diffuser glass, avoid touching the lens with your fingers to prevent sweat or oil marks that can dull the reflector and reduce its efficiency. 2. Regular Inspection: Periodically check and adjust the headlight beams to ensure the illumination distance meets requirements and the beams are aligned vertically. The diffuser glass should be correctly installed according to specifications to prevent loosening or misalignment, keeping the prism vertical.
My car also experienced the issue of daytime running lights turning yellow. The main reason is that the plastic lens cover, after prolonged exposure to sunlight, undergoes material aging and oxidation due to UV radiation, causing it to yellow. If the car is parked outdoors for extended periods under constant sun exposure, the plastic starts to yellow and fade, much like old toys. Additionally, some car cleaning agents with overly strong alkaline properties can corrode the surface during washing, accelerating discoloration. In areas with poor air quality, accumulated dust and pollutants can also make the lens cover more prone to yellowing if not cleaned promptly. I recommend parking in shaded areas whenever possible to avoid direct sunlight. When washing the car, use specialized pH-neutral automotive cleaning products instead of household chemicals. If the lens has already yellowed, try polishing it with automotive polishing compound to restore brightness. If that doesn’t work, consider replacing the lens cover at a professional shop. While this issue doesn’t affect the light’s functionality, it makes the car look aged, so regular maintenance is crucial.
