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PCV assembly / valve replaced, still having issues (and more)

My car has been idling VERY rough the past week, so bad that it starting to die at stop lights. It would start back up, but only keep going if I was on the gas. I ended up freaking out and taking it into a local shop. They told me my PCV valve needed replaced, and that it had a misfire as well as the oil cap wouldn’t even come off when it was running (don’t know if that’s a thing). So I agreed to have it replaced. I went this morning to pick it up, and even though they said it seemed to idle a bit rough at the start it seemed to be OK now. Well it wasn’t I drove one mile to my work and it was idling again all crazy. I turned it off and back on and it had a tough time starting (but did). And the very bizarre thing is my A/C no longer worked and I ended up with a “stability control error”.

I promptly ran it back up there and talked to them. They look really baffled, but did mention if a code got flipped in some cars the A/C no longer will run. I have never heard of that before, but I guess if it’s true maybe it relieves load off the engine?

Anyhow I am sitting here a bit freaked out as I am broke and I have no idea what they are going to say. So I wanted to ask around and see if the rough idle, starting symptoms line up with a bad PCV valve. And if anyone had heard of the A/C shut down situation…

Thanks for the help!

Find another shop.

Is the check engine light on? Could be a few things, EGR, bad coil, low fuel pressure, vacuum leak. Check the Mechanics Files link for a mechanic in your area.

No check engine light, which is so weird to me. I picked it up, they have no idea what’s going on. They did of course replace the PCV assembly, but now I have the other issues.

They gave me a print out of the error codes however, but it doesn’t help (me at least).

15128-P030200 : Cylinder 2 misfire detected
26384-U112300 : Data-BUS Error Value Recieved
22049-U042400 : Invalid Data Recieved from HVAC Control Module

I am hoping the misfire is tripping the rest, meaning my HVAC is OK.

Need to know what engine and the year of the car. This will determine whether or not you have an IAC (idle air control valve). Does it run OK when not idling?

I have a 2015 Passat with the 1.8T

It seems to run fine otherwise. So many of it’s symptoms seemed to line up with the PCV valve so I felt pretty good about them replacing it. I am crossing my fingers that the only issue is the misfire, hoping it’s only something like an injector. They replaced the coils and plugs back in may (dealer).

Thank you very much for the help! I am so stressed right now.

Guess that rules out an IAC. Sorry.

Thank you for checking it out! If you drive on a bad PCV will it do something like build up carbon? Will carbon cause a misfire?

swap plug coil with an adjacent cylinder to see if failure moves.

That sounds like a good idea, but I don’t have a way to check it. I can’t believe that they didn’t think of that. =(

If you don’t live in CA, you get the codes read at a local AutoZone or Advance.

I live in Missouri, I assume it’s easy to swap them. I mean they just plug in right?

THere is a connector on each coil with a locking tab. Pull them off and then pull the coil up. Swap them and push the coil onto the plug. Should hear/feel a slight click when it locks on. Then plug the connectors into the coils.
Here is what they look like.

Not to be a pain, but I assume the wire can be switched from coil to coil so they still fire in sequence? Very stupid question I know (LOL).

To Determine if it is a bad coil.

Number two is the suspect (second from the right facing the engine.
Unplug that coil and coil 4 (far left coil).

Remove the bolt that holds those coils in place. I 'm pretty sure the bolts are 8mm,
Swap the two coils by pulling straight up on the coil.
Secure the coils with the bolts and plug them back in.

Clear the old codes.

Start the engine and take it for a short drive.

Re-read the new codes. If that coil that WAS in number 2 was bad, you should now get a P030400 code.
If you still get a P030200 then it is either a bad spark plug, valve, rings, or maybe just a bad wire somewhere.


Just an update, it was found that I had a bad injector. The original mechanic obviously just “guessed” and charged me to replace the PCV valve… 390 bucks… wtf