I've noticed that one of the headlights in my Ford Focus has become opaque. However, this doesn't seem to match with what people call "foggy" or "hazy headlights": not only the fog is not evenly spread (it's more of a "stain"), but it really looks like it is the inside of the lens that got opaque, not the outside.

Some friends suggested that the lamp may not be the right one, and that it gets too hot and burns the plastic. However, I didn't change the lamp myself when it broke, but I had it changed in a shop. Also, the same shop changed the lamp in the other headlight, which is fine instead. Some suggested that maybe when the previous lamp broke it sent out a quick burst of heat which caused the damage.

It is more of a side stain, it doesn't sit in front of the lamp and it doesn't seem to affect the projection of the light, however some people suggested that it might be an issue for the next mandatory inspection (I live in Italy). Anyway, it's a bit ugly, and I would really rather fix that.

Is it possible that the damage is on the inside? If that is the case, do I have any other choice than to replace the headlights?

Thanks in advance.

EDIT Here are a few pictures of the headlight (they're a bit dirty, sorry about that, but the issue is quite visible): 1234

For reference, here is a picture of the other headlight: 5

  • 2
    I think if you could post a picture of the headlight it would help get you answers, it's hard to visualize from your description.
    – GdD
    Commented Jul 28, 2017 at 8:25
  • Is it a HID lamp?
    – Martin
    Commented Jul 28, 2017 at 9:17
  • @Myself (funny :) ) I have no idea. How can I find out?
    – Simone
    Commented Jul 28, 2017 at 10:09
  • 1
    If the headlamp is hazy at all, try polishing it anyway. It may surprise you with it actually having the haze on the outside and not the inside. You say "it really looks like it is the inside", which seems to tell me you really don't know. It could be worth a shot. Commented Jul 28, 2017 at 10:49
  • 3
    Could it be trapped moisture? I'd try taking it off and seeing if I could polish it from the inside.
    – GdD
    Commented Jul 28, 2017 at 13:13

2 Answers 2


Headlights can quite often suffer from condensation on the inside of the lens unit or protective cover.. Sometime you'll notice this get better in the sun as the heat evaporates the moisture?

As you say the bulb has been changed condensation is possible in the light if the rubber protection boot (at the back of the headlight) has not been replaced properly, as moisture will then get in there and into the light unit itself.

  • You know?...from the first picture, my answer above looks relevant, but now looking at the second photo, water droplets towards the bottom of the reflector make this answer more probable. Dry it out before your wires get corroded!
    – Ted Pants
    Commented Aug 4, 2017 at 1:51

Don't rule out absolute UV damage. I've seen this occur to acrylic when exposed to strong sunlight repeatedly reflected off glass buildings. Ever hear about the car in England that caught fire because of Archimedes Len's effect? It happened to my motorcycle lens just like this one. It's not from the bulb(s), if it's not moisture, it's the plastic. If it's only on the exterior surface, try rubbing a circle with toothpaste and see if it improves. If it improves, get a headlight polishing kit. And park differently. Cheers!

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