2005 Cooper S Code P0302
 

I have a 2005 Mini Cooper S with 102000 miles. Had an intermittent CEL now the CEL flashes and car runs extremely rough. Code scanner showed P0136 and P0302. Replaced plugs, wires, ignition coil, and after cat O2 sensor. While replacing plugs noticed plug #2 had oil on the porcelain and the threads but not on the electrodes. Code P0136 is now gone but P0302 remains and CEL flashes as soon as you start car. HELP!

Bad spark plug seal on the valve cover, maybe.

https://www.obd-codes.com/p0302
https://www.northamericanmotoring.co...2-misfire.html

P0302 is a cylinder 2 misfire so if you're still getting that and your check engine light is flashing at you, there is still an issue at foot. I'd also get this resolved before driving the vehicle. Just as a test, I'd try swapping injectors around to see if the misfire follows. I'd also probably suggest checking valve cover as well and just double check the spark plug hole gaskets (here). Check through those steps at the above listed links and if nothing is showing to be your issue you may want to do a compression/leak down test.

I had a similar issue in my 2005 s. I was getting p313 in conjunction with p302. Long story short, I needed to get a computer update and it went away.

Replaced valve cover gasket, spark plug tube gaskets, and swapped #2 and #3 injectors. Code P0302 remains, misfire did not move with injector. Guess I'll try a compression test next.

Check back with compression numbers, timing being off can also cause random misfires.

I've had luck cleaning the map and tmap sensors for issues like this. They tend to get oil fouled after a while. Doesn't cost anything, and doesn't take very long.

Why the after cat o2 sensor? It has little to do with engine management - mostly gives data on Cat function. Did you use a high quality sensor? The cheapie cause all sorts of problems. Do you have a way to reset engine adaptations? I would...