I have a 2004 Buick Park Avenue, naturally aspirated with 160,000 miles on it. I have noticed in the last few months a burning smell coming from the car, and it smells like plastic. I have been trying to pinpoint this problem, but every time I think I have it figured out, it turns out to not be anything. (first the seat heater, maybe something in the heater itself). I feel like it is also worth noting that I have 2 subs in the trunk on a 1000 watt amp.

I'd suggest disconnecting anything aftermarket as a good start.

Does the smell get better or worse if you turn the blower on high and turn off Recirc?

Does the smell happen only when running? Driving? More details please!

okay. So, the smell started happening about 6-8 months ago (2 years after I have installed the head unit and the subs in the trunk). I drive in the morning with my seat heater on, my heater on, and sometimes my rear window defogger on, and that seems to be when the smell becomes the most prevalent. Except sometimes, it just doesnt smell. I thought it was the seat heater burning, but i left that on for a long time and nothing happened. I cant really tell where the smell is coming from either, it seems to be coming from somewhere in the front of the car rather than the back, but its so inconsistent that I can't pinpoint anything that would be causing it.

also yes, only happens when driving.

Is your back window tinted?

Are your seats leather? If so, they give off an odor after several years as they begin the inevitable decline into death. But, Thanks be to God who keeps it into a looonnng death many years down the road when it'* shell will be a rotting mass.

The radio antenna control module is on the passenger side, ahead of the rear window, behind the pillar cover.
When it starts to go they get super hot, and really can smell bad/stinky electronic smell . I am surprised mine did not cause a fire.

no, there are decals on my back window though.

ill check that out. Thanks!