It is plastic. I'll give this a try and update once done... Thanks for all the info. Dirt got in when I went to an automatic car wash, too much pressure water and soap, the headlight is probably not sealed 100% anymore...It did not come from the back as I have both covers on...
Sure if you want to give it a try that would be great! But why wouldn't the heat gun work?? If I do small sections at the time, heating pulling a bit, heating, pulling, ... wouldn't that work? I'm not sure I would put the complete headlight in the oven as there is a lot of stuff that could be damaged...no?? Also, the AHL module is attached to the headlight housing. I'm not sure it handles high heat so well. What temperature what you use and for how long?? Like 200 F for 30 minutes??What B~P said.
I have an old broken xenon unit I can stick in the oven. Id hate for you to ruin a working set. The heatgun likely will not work for this. The reason they get stuck in the oven is they need to be heated slowly and broadly for the heat to penetrate into the glue areas. A heat gun will likely get the surface too hot before it will penetrate to the glue. Been there, done that.
I guess we will find out at what temp the glue loosens. I dunno. Ill just start out low and work my way up. The problem with the heat gun is exactly what you said. You can only do small sections at a time and that usually leads to a cracked lense since one section is hot and loose and one is cold and stuck. Ive tried it on an old corner light, so Im saying this from first hand experience. It also would make the job painfully slow since you would need to heat each section slowly so you dont fry the plastic before you heat the glue.