6 DTCs, help?

**MDRracing13** · 01-30-2012 01:05 AM

I bought my car to my friend's shop for an oil change. While driving home I noticed my car running funny. Weird idle and running kinda rough. The CEL comes on and I pull over to pop my hood. I found out that he didn't lock my oil cap all the way and it had popped off. Oil was all over, but I did not lose much, maybe a half quart. My car immediately ran better so I ignored the CEL. The CEL finally went off.
Now it came back on after a week, I noticed the car running a little rough on idle. It got a little shakey for a second then went back to normal. After I shift I notice a slight hesitation too. I went straight to an autozone to check the codes.. this is what i got:
p0301
p0304
p0307
p0507
p0300
p0431, then a p0431pd (no idea what this is)

My question is, are all of these codes from now? Or do they save since i never cleared them from when the oil cap was left off?
Also.. anyone know what this could be?? I'm assuming new sparkplugs, coilpacks, and valve cover/sparkplug gaskets will do the job.

**BaconBait** · 01-30-2012 01:34 AM

Leaving the oil cap off wouldn't cause codes.

Ross-tech Code Listing

p0301 - Cylinder 1 Misfire Detected
p0304 - Cylinder 4 Misfire Detected
p0307 - Cylinder 7 Misfire Detected
p0507 - Idle Control System RPM: Higher than Expected
p0300 - Random/Multiple Cylinder Misfire Detected
p0431 - Warm Up Catalyst; Bank 2: Efficiency Below Threshold
p0431pd - Don't know what the pd means.

Looks like the p0507 is the main culprit. I'm not familiar with the 4.2L, but I'd start by looking for a vacuum leak and making sure the oil spray is cleaned up as best as possible.

**Joey** · 01-30-2012 07:43 AM

Thanks for posting the definitions of the codes, Bacon.

It is possible that the oil from the loose cap could have gotten on the coils and caused them to fail. That would explain the multiple misfire codes and the specific cylinder ones. Easy way to test is to swap the coils giving you codes to another cylinder and see if the faults follow. If they do then you have a few bad coils.

I have a bunch of spares i would let go for cheap. Let me know if it comes to that and if you need any.

**MDRracing13** · 01-30-2012 12:37 PM

Thanks guys, I appreciate it! I'll try swapping out the coils and ill let you know

**norcal** · 01-30-2012 03:00 PM

Leaving the cap off (or the dipstick out) will cause irregular idles and also whatever it's called when you let off on the gas and the engine RPM takes an overly long time to return to idle. If it's bad enough I'm sure that would throw a code.