Can a bad PCV valve/grommet cause a PO301code and rough idle?

[davisfj62]

I have been chasing the following codes this afternoon: PO300, PO301, and PO302

From past experience and reading dang near every thread on PO300 codes I automatically thought coil packs. I always keep a couple of OEM coil packs on hand and replaced both the No. 1 and No.2 coil packs and I'm still getting a check engine light, a PO301 code and the rig is running like crap. I have checked the plugs on no.1 and No.2 and they look fine.

I seem to recall a thread that discussed this same issue and the culprit was a bad PCV valve/grommet. Does this sound familiar or does anyone else have any suggestions for the next diagnostic step?

Thanks as always.

 

[JunkCrzr89]

Yes, a bad PCV valve or PCV hose could cause P0300-0308. However, that’s pretty low on the list of possible causes.

 

[spressomon]

Started experiencing similar symptoms. I can clear the code(s) and it will run OK for a day or two...then pull one or more 30x codes.

 

[blinkerfluid]

Check fuel tank cap, if loose or bad those things cause all sorts of stupid codes

 

[Carpenter951]

Yes, a bad PCV valve or PCV hose could cause P0300-0308. However, that’s pretty low on the list of possible causes.

Agreed, but it's easy to check to rule it out. In my case, the hose was so bad it crumbled when I touched it.