I have a 2007 chevy cobalt 2.2L. I went to autozone and got the code checked out and it was the camshaft positioning sensor. A while back when I changed both exhaust valves for the number 1 cylinder I notice that the camshaft positioning sensor reads off the intake camshaft. When assembling everything back together I started the engine and the check engine light went on. Took it to autozone to get it checked out and they said that code P0340 was pending. So I took the car out for a spin so the engine could get back to its regular self. After about 10 miles of driving I got the car checked out again and it still read code P0340. I'm thinking the timing might be off just a tad but when I put everything back together the timing marks on the camshafts and crank were where they were supposed to be. Can someone give me a remedy to this problem.