Ok so I had onstar do a diagnostic on engine and nothing. So I took it into my Machanic and he checked and it stated that the oil filler cap needed replacing. Or so he said (he is pretty honest). I figured he maybe right, seeing how I put on the new fangled one from 3800performance.com, you know the chrome one with the filter. Anyway has anyone heard of this. I just wanted to dress up the engine compartment with a little chrome. But if this is not a good thing then I'd really like to know. Thanks

This what your looking for? ZZ Performance Personally, I have never heard of a oil cap giving a error code.

Let'* get this straight.. you put a breather on where your valve cover cap used to be?

Makes sense to me that you caused a check engine light. Most of the 2000+'* that I've scanned run lean and would be pushed over the edge when you introduced the breather cap. The reason behind it is that the breather allows fresh air to be pulled into the crankcase and pcv system. More air than is usually present is being pulled into the intake via the pcv tract.

The short version is ....you created a vacuum leak. Try replacing the breather with the valve cover cap and drive the car at least 3 times of about 10 minutes and the light should turn off. It takes 2 consecutive times to turn on the light from minor codes and 3 consecutive good time for the light to go off.

Thanks. Will do!

I hope I'm right. =0)