Engine Light On and On and On

Purchased 2008 Cobalt (29k mi) on 1/19/10. Almost every week since have taken back to dealer for same warranty work: engine light on. Dealer shop is great to work with, but the problem is only fixed for 24-48 hrs and then recurs. Always “300” type problem code (engine misfiring somewhere). After six trips to the shop, this is still happening. I have called GM Customer Assistance and they now have a ‘specialist’ involved. The car drives fine.

What might be causing this? I mean, after all this time (like when it was first put in to use), shouldn’t the engine light be acting up before now?

One idea I had for the cause of this problem, is that the car was previously owned by a rental car company in Hawaii. We live in Wisconsin and it is a very cold winter. The dealership tells me that the car’s onboard electronics makes the adjustment to climate, and they haven’t gotten any problem codes to indicate that it isn’t working properly.

Have they checked the engine’s compression? If so see if you can find out what the results were.

It would also be helpful if you went through your invoices and told people what has been done. Otherwise all people here will do is tell you things that you will say have been done already. So maybe save everyone some work.

The P0300 trouble code is for “random misfire”. Is the code P0300, or is it P0301, P0302, P0303, or P304?
Does the engine have an actual misfire, or does it just have the code? Does the engine ever buck, jerk, or run roughly? Are you using the correct octane gasoline?
Are there any other engine performance problems?

Thanks for the info everyone. I was informed this morning that the GM Zone Manager is involved and hope that this will be resolved shortly! I’ll let you know what the outcome is.

Good luck, hope it gets resolved. EVERY car maker has these poor bad apples. Luckily it is a very small percentage but sure is PITA for owner.