So I recently purchased my 2008 XC70 (3.2) from my roommate. I knew that he had small issues with it and that is all fine. He did mention that once a month or so, this check engine code (P0301) comes up. He has replaced the coil pack and the spark plug, and seems to think it is a leaky injector. Before you ask, yes we did swap cylinder 1 with other coils and plugs and still have had the same issue and code. So it is something specific to this cylinder.I was just curious if anyone else has had thtis issue pop up and how did you deal with it. Along with the P0301 on cold starts every once in a while, I am now getting P0420 stating Catalyst Efficiency.... Is it possible it is the catalytic converter, or should I be checking other components first. I have uploaded a screenshot of the system when the code was thrown. Any input is welcome! Thanks in advance.

I posted pictures with this just for reference.

 

So the P0301 is saying that a misfire in cylinder 1 (nearest the timing cover) is being detected. Could be spark, could be fuel or could be compression. Seems you've ruled out spark (unless there's an issue with the wiring harness/connector to the coilpack) so next would be to either swap injectors between 1 and 2 or do a compression test to make sure there's not a burn valve etc. The P0420 may not be totally unrelated. This code is saying there's too much O2 after the cat converter which can point to a fuel trim issue, an exhaust leak or a gunked up cat. Fuel trim issues can be caused by fuel pressure, air leaks, MAF or temp sensor issues, O2 sensor issues etc. As to a gunked up cat, you may need to correlate to other symptoms. Are there any other things going on like excessive oil consumption or poor fuel economy or low on power?

 

I went ahead and took a little video snapshot on my phone using the OBD2 reader to show the 02 sensor activity and this was the result.

 

Grrr.stop buying cars that don't have current smog.its illegal and if you were to go to court you would win.the law is in place for a reason.No it doesn't matter if the car was sold "as is" it's illegal period.There I said it.Ok now on to the good stuff- here are your options: either do a leak down test and find out WHERE the leak is going ,Or - hook it up to Vida Dice and get a reading to see if it's ignition related.Next is replace intake manifold gasket.if it's reading lean u either have a intake leak ,a clogged injector,a burnt valve or somehow someway a timing issue....if it's vvt u have a possibility but you would get a cam crank correlation code far as I know so probably not.A misfire can be tricky but there's only so many reasons it can happen.last reason I can think is the injector is missing the fuel pulse......that would be computer based.Dont ever buy a car that doesn't have current smog.No matter how appealing it is.good luck.