Code p0326

Same thing happened to my 2008 Cobalt - I have a code reader and got the same problem code - p0326. "Knock" sensor pertains to spark knock & usually indicates that the timing is too advanced or gas octane is too low. Simple fix; I put a tank of premium in mine (after turning off the code with my code reader) and that kept the check engine light off. Since the engine computer "learns" by running, it will eventually adjust the engine to an optimum running condition; HOWEVER, when the check engine light comes on, the computer resets everything to the default settings until the code is turned off and stays off, so your engine is probably running rich and the timing somewhat retarded.

Also, remember the wiring is deteriorating on these older cars. (Trust me, I have 4 of them) Just because the scanner says a sensor has failed it may no be the actual sensor. It may be the wiring that leads to it. Do all your diagnostics before spending more money on parts that may not be needed. If you don't have the skill to do that then have a shop do it. It will save you money in the long run.