Thread: 98 GP GT with a PO442 code and light on.

Generally speaking, when that code pops up, the gas cap is the first thing to look at. If you replace it with a quality cap and the code remains, then its probably going to be elsewhere. A possible way to tell if it is the cap is to note whether or not the code comes on after such times as filling up with gas.

It could be a vac leak I suppose but Id still start with the gas cap.

I would start with the gas cap as well. And when replacing it, make sure that your filler neck is in good condition. One car I had, the gas cap was brand new. But the filler neck was rusted and not sealing well, giving me this code. Replaced the filler neck with a good one from the yard, and all was well.

But like scotty said, could be a vacuum leak as well. But I would start with the gas cap.