I have a 2001 gm ls,I had an amp installed at a local shop and the dummy screwed a hole in the gas tank. Since then i've had the tank replaced but the check engine light comes onevery3 days or so. I had the code read, its a code 42 they keep telling me its the gas cap so i bought a new one and the light still comes on any ideas ?

 

If the gas tank is not sealed (air tight essentially) you get that code. The gas cap is the most common culprit. Since your tank has been replaced you probably have a vapor leak somewhere else causing the code.

Who replaced the tank? The dealer?