Chevrolet Cobalt owners have reported 2 problems related to service engine light on (under the engine and engine cooling category). The most recently reported issues are listed below. Also please check out the statistics and reliability analysis of Chevrolet Cobalt based on all problems reported for the Cobalt.
Service engine light on along with traction light which appears when engine gets hot usually at an idle. So when traction light is on & your driving in normal traffic, car will slow down and you'll have to step on gas really hard to keep up with traffic, if and when transmission decides to shift gears it will bang really hard into second gear .
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Service engine light has been on intermittently for a year. Dealer said it was probably due to a loose gas cap and nothing more. Engine started shaking when stopped at stop lights and the service traction and traction off lights would come on. The engine light would start blinking, and if the car was stopped for too long the engine would shut off. One mechanic said it was the cam shaft, which I got fixed and still continued to have the same problem. Took it to another mechanic who replaced the cylinders. Problem continues to occur which engine shutting off if stopped longer than a minute.