GM like other manufacturers have Tech Assist services to help techs. Techs are to report back with corrections, which becomes a data base to aid future techs with similar concerns. GM only helps back to the 2000 model year at this time.

 

I would just like to add to this thread

I was getting the P0300 code as well on my 2001 SLS. I replaced the serpentine belt today because it had worn enough to break in one spot. I was getting random engine light flashing all the time (every 10 miles at least with an always on light) and have driven 30 miles since and NO LIGHT! I am at 51k miles and I'm certain it was the original belt.

If you have an inexplicable engine light this is definitely the first thing to do.

 

Is there a Technical explanation why the Serp Belt would cause misfires? It doesn't seem to make sense. It runs from the crank to th alternator, to the idler and tensioner, to the ac compressor, to the alternator, to the P/S pump and back to the crank!

 

I think the idea is that it causes the misfire sensors to believe that there was a misfire when there was not. Also potentially then the engine tries to correct for a misfire that didn't happen?

 

thanks for all the information guys