On the 2006 Chevy Cobalt, when the Check Engine light is “blinking” this is the universal sign for “P0300-Random Cylinder Misfire”. This means that one or more of the cylinder is not firing correctly. Unfortunately, there are many different causes of a random misfire. This can be; faulty or worn spark plugs, a faulty ignition coil, a faulty ignition control module, intake air leaks, etc… On this vehicle, due to the setup, a very common problem associated with this is a problem with the coils and/or control module. At this point, best bet is to start with the spark plugs. Inspect them for any cracks in the body or worn diodes. Replace as needed. If the spark plugs look ok, or replacing doesn’t solve the problem, I would suggest having the Diagnostic Trouble Codes (aka “P-Codes”) retrieved from the on-board computer, and see if there are any other codes besides the P0300 that may give a little insight as to where the problem lies (like an ignition control module code, or a “lean” code that would point towards an injector or air leak problem). You can have these p-codes read FREE (except in California) at any local “big chain” part store (ie. AutoZone, PepBoys, Advanced, etc). If there are any other codes, the associated items would need to be looked into. Or the P0300 is the only code, then deeper testing and diagnostics would need to be done.
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