I have 2006 Chevy cobalt LS 2.2 keeps throwing p0300 and I changed coils, ignition module, spark plugs, fuel filter, my battery reads 12.45. I don't know what to do.
Please help.
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Clarification: What is the mileage?
Yes sir sorry about that it has 145,331
Check all of your grounding connections for looseness and corrosion.
https://www.autocodes.com/p0300_chevrolet.html
Have you checked your connectors/wires & made sure each connector is hooked to the correct cylinder?
Yes sir what's crazy when the code pops up car misses when I clear the code car runs perfect for about 150 Miles then throws the same p0300
Sometimes it might seem to run slightly better during the relearning cycle after you reset but since it keeps coming back there's either something you missed or the replacement hardware can be defective. So try swapping for another set as well.
Have you been able to isolate it to multiple misfires on one cylinder or is it across all of them?
Depending on where the parts come from you can have failures do to cheap manufacture , having to swap them out numerous times.
I had this issue with an ignition control module in a 97 bravada. I went through over 20 in 4 years & they kept failing without rhyme or reason. Apparently I wasn't the only one as the guys at the parts store said they got countless complaints.
As @doc mentioned, don't forget to check for corrosion (usually blue or white colored, Electronics cleaner & a extra firm nylon brush will clear that out) & that your grounds are not loose at all.
It only takes one slightly loose or corroded ground to mess with modern electronics.