P0331 and limp mode.

[rguzz]

96 850t have had this code P0331 for a while and car feels way underpowered. 200k miles on original sensors and wiring. Have run several tanks of Shell 93 octane. Stage 0 with PCV a few months back can't recall how soon CEL came on after that but somewhat soon after PCV and I could have disturbed something. Just replaced turbo actuator because of over boost and cut off. No longer have that. I have a blow off valve rebuild kit though I doubt this has anything to do with my current problem. Pings a little under load but slow to take off though cruises okay. Doesn't appear to run rich. In a nutshell, I assume limp mode and have P0331 and don't know what to do next. I have disconnected battery overnight without a change. CEL is not always on but will return immediately if I accelerate a bit hard which I try not to do. No change in performance regardless of CEL on or off. Limited diagnostic tools except for CEL re-set capability.

[bmdubya1198]

Have you seen this thread: http://volvoforums.com/forum/volvo-850- ... ors-41240/ ?

[rguzz]

Thanks, I have but don't really understand it unless it basically means time to do a series of diagnostic tests that I won't be able to do. How do you get to the wiring, etc. Are there one or two things that seem most likely to be causing this problem? Can we narrow it down a bit?

[polskamafia mjl]

Well the PCV system is located right by the knock sensors. If the code came on soon after you did the PCV I would take the manifold back off and start by inspecting both of them.

[rguzz]

I'd say CEL within 2 mos of PCV job. I guess I'll need to look unfortunately. If I have to go back in there again I'll do FCP's upgraded knock sensor kit.

[polskamafia mjl]

Hmmm, 2 months is quite a long time. It may not be related after all but still a good place to start I think.

[240gator]

OP, did you ever figure this out? I have very similar situation.