Engine light comes on without any warning and the dashboard alert engine power reduced. Unable to get the car to accelerate past 25 miles an hour. Sensor reading throttle issue service pending with Chevrolet dealership. I have had problems with the engine light coming on in the past - no other warning and the engine idles very badly especially wit heater or air conditioner on - past service repair have never found an issue. Very alarming that the reduced engine power just comes on at any time now.

Update from Mar 13, 2017: After a $1400 repair bill and the issue re occurring in 2 weeks and the next repair bill estimate was $3000 with no guarantees it would fix the issue and a car 10 years old with 138,000 miles I opted to buy a new car. Thanks for all the feedback good luck to all the cobalt owners

traction control light comes on all the time and randomly. i can be idling and it comes on. it makes the engine light come on and shifts rough. I have taken it twice to chevy dealer and they replaced some sensors but it did not work. they want to run an hour and half diagnosis for $181.00 and I said no. How many things could it be?? its obviously not the stupid sensors they replaced twice!! surely there has to be other cars that have had same problem where they would have info. the car is 10 yrs old now. other than that its fine

Had 3 Chevrolets before I bought a Plymouth Colt which I kept for 8 to 10 years. This is the second Chevy since then -- had window problems with the other one and now the check engine light comes on and the dealership can't find out what the problem is!

Update from Feb 2, 2010: Went from bad to very good! About 3 weeks ago, while stopped at a stop light, my car stalled (never did that before). Now it was beginning to become a safety issue! The only problem was that when you wanted the car to have the "check engine" light on OR have the car stall on you for the dealer, of course, it wouldn't do it. They had it in one week--spent 2 hours on doing diagnostics and checking with Chevrolet. Could find no code in the system so they asked to keep the car for another day to run it. They ran it 85 miles and, of course, nothing happened. I picked up the car that afternoon and the next morning after running it for about 10 miles to an appointment and then stopping for breakfast, I went down the street, the "check engine" light came on again and I then had to stop for a red light! Lo and behold, it stalled on me while waiting for the light to change---this time in front of a school bus! Two days later I went to a flea market about 20 miles away and then returned home---no "check engine" light during that entire period. I stopped at a grocery store near home and the light went on twice on my way home. The next morning 5 instances of the light coming going about 15 miles away and then only once on my way home. I took it in the next day again. They did some other kind of test and hooked something up to the car and drove it around and to one of the employee's home overnight and back again to the dealership. Lo and behold, the light went on several more times for them and it had a code this time! It appeared to be in the engine module -- something about a power train. They had one in stock and replaced and asked to keep it again overnight to run it back and forth! That seemed to have worked as I've had the car back and have had no stalling and no "check engine" light come on. The dealership did a great job in finding the problem as I said, there was no rhyme or reason as to when the problem would happen. It's great to have a well functioning car again!