Hi, I searched and could not find anything. I have gotten the engine light on and after scanning for codes got a PO 103 cylinder 1 misfire. After several starts, the light goes out, then a few days later will come on again.

Any ideas what it means? A friend told me the plugs and/or coil packs could be bad.

 

Firstly; Pzero103 is cylinder 3 misfire.

The code will reset itself if the condition does not repeat in a certain amount of starts.

It could be anything! requires troubleshooting not throwing parts. spark plug,coilpack,injector,head gasket among others.

 

wow. I thought the code would lead to a more narrowed down, specific diagnosis.

 

It does. Cylinder #3 occasionally misfires.

Troubleshooting is what technicians are suppose to do, the guy at AutoZone is supposed to sell parts after he misreads his scanner.

 

You didn't mention what year/model/engine you have, but to start diagnosing it, you can try SWAPPING coil packs (if so equipped????), and sparkplugs. Replace the plugs anyways if they have lots of miles on them.

My 2.4 was doing a similar thing with the p0303 - would clear up after a bit of injector/fuel cleaner - then tried SEAFOAM in half a tank (ran it till almost empty), and the problem has not come back since (2 months ago).

 

That was my scanner read, and I will check it again, but I could swear is said cylinder 1. I hear what you are saying about other possible problems. My mechanic friend was just saying that the most common cause for a misfire is the coilpack and/or plug. I have over 70k miles, and have the original coilpacks. Changed the plugs once at about 10k miles-put in Autolite, a tip from a long-gone HHR enthusiast (SoCal HHR) that I believe was an engineer, but also wrote auto articles and worked on cars. He had done extensive testing with his HHR, and found the Autolites to give improved performance. I used my GTech timer and they actually reduced 0-60 times by 3 or 4 tenths of a second (I know that is hard to believe).

 

But for everyday driving these little Trucklets need their AC Delco 41-103 iridium spark plugs, the Ecotec is designed around this plug! If you still have the originals they still have 90,000 miles left on them!