Hello all,
I have an issue with my 2010 HHR (2.2). code reads PO301 Cylinder one misfire. I replaced the spark plug and coil pack on the first cylinder closest to the passenger side (which would be the front of the engine in my opinion). should the fault have cleared itself or do I have to clear the fault manually via a reader OR did I replace the wrong one??? Thanks in advance,
Dennis

 

That is number 1. However, just because the description of the code is "misfire on cylinder 1" does not mean a plug or coil problem, it means "find out what is causing the misfire on cylinder 1". Could be an injector or a valve or a head gasket among other things.

Use the search box near the top of this page for lots of info about misfire causes and fixes. That code should reset itself after a few cold start/warm up cycles if the condition is fixed.

 

... or to clear the code you can try disconnecting the NEGATIVE side of the battery for a couple of minutes. It should do the trick.