Multiple Engine codes HELP!!!
 

Hey volvo family new to this site and was hoping to get a little help on my 2.9 turbo turd. I have (CEL) codes out the ying yang and need help solving them.
1st code:P0351
2nd code:P0353
3rd code:P0356
4th code:P0352
5th code:P0420
6th code:P0234
now I know the first 4 codes are miss fire codes but I just put new NGK platinums in and still no fix. Is it likely to lose four cool packs at once? And I assume the P0420 is for the catalytic converter? And not sure what the over boost is about as well? Any help would be great😞

Your "Over Boost" may be the cause of the other codes, causing a lean condition misfire and maybe over heating the "CAT".
You may have a vacuum leak going to the "wastgate" and it's not dumping some of boost.

Here's a video of how to troubleshoot..

So I should start with the over boost code first?

Short answer yes, don't go throwing parts at it. Find the reason for the overboost that may have caused the other codes. You may get away with a 2$ vacuum hose like in the video.

+1 on MM's advise. Start with the vacuum lines as that can cause lean trim issues and issues with the connected actuator. Also spray around for possible cracks in intake tubing - its possible overboosting blew a hole or cracked an intake air path component.

Awsome thanks a lot guys I'll give that a try and see what I come up with

First thing - don't panic. Trust these guys in the forum, they know what they are doing.

Things to Check:
Vacuum Lines (google how to find vacuum leaks) - it's likely that this is the culprit of MOST of the problems you are having (if not all). I would check/replace the PCV lines, unless you've done so recently thats worth doing - even if it isn't the "problem" here.

Get an OBDII reader - they are cheap, and will give you more information. I like the BlueTooth type, so it pairs with the phone and you can actually see a little more information. OR get a Vida/Dice setup(or whatever the current/corrent version is called now) that will give you A LOT of data to look at.

I just had a similar problem with my XC90 - T6 (P0420 code) you can see the progress here 2004 xc90 t6 - p0420 (don't know if posting ext. links is acceptable on this forum... but it's worth a shot)

Adam

Im dumb, clearly you have some sort of OBDII reader. Carry on.