What Causes Daytime Running Lights to Turn Yellow?
4 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.
Yellowing daytime running lights are quite common, and I've seen many cars like this. The root cause is the aging of the lamp cover material. Plastic, when exposed to long-term UV radiation and high temperatures, oxidizes and turns yellow. Cleaning methods are also crucial. Using the wrong cleaning products, such as those containing alcohol or strong alkalis, can accelerate surface corrosion. Parking by the roadside can lead to dust accumulation, and prolonged friction from dust particles can also cause the lamp covers to yellow. I recommend that car owners not be lazy when washing their cars and use mild automotive cleaning solutions to clean the lamp covers. Try to park in garages or under shade to reduce sun exposure. If the covers have already turned yellow, try gently wiping them with baking soda or toothpaste using a soft cloth—sometimes this can be effective. However, if the damage is significant, it's better to replace them. Developing good maintenance habits can extend the lifespan of the lights and keep the car looking neat and attractive.
Yellowing of daytime running lights typically stems from the aging and oxidation process of the plastic lens cover. Prolonged exposure to strong UV rays at the front of the vehicle causes molecular structure changes in the plastic, leading to discoloration. Certain vehicle models using materials with poor UV resistance are more prone to this issue. External factors like air pollution or improper use of chemical cleaners can accelerate the process. While the internal LED light source usually functions normally, the cosmetic damage affects appearance. Preventive measures include parking in shaded areas and regular maintenance with UV-protective cleaners; existing yellowing can be improved through professional polishing or direct lens replacement. Prompt attention helps prevent potential problem escalation.
