2000 V70XC Cat Converter P0422

Post by **FlyingVolvo** » 27 Feb 2010, 22:15

Today after a long, fast highway drive I got the lovely "Main catalyst below threshold (bank 1)" code (P0422). After reviewing similar topics in the forums, I'm a little skeptical that the cat converter is really the problem. It's got 135,000 miles, many of which are highway. The car has never been abused, and O2 sensors were replaced with genuine Volvo when they died many thousands of miles ago.

Just recently completed a 1,000 mile round trip and then the 400 miles today. The P0422 was the only code to show up, and shortly thereafter it disappeared and did not return for the remaining 200 miles of my trip. When I got back home, I plugged in my scanner and there were no fault codes stored. Oxygen sensors seemed to be reporting normally as far as I could tell.

I am not currently burning any oil that I am aware of, although there is a small leak somewhere near the turbo I believe. Currently running Pennzoil Platinum 5W-30 with added Lubro-Moly (MoS2, tested for catcons and turbos). I run 91 Octane Premium gas. I always get the car up to operating temp; never any short hops. I did the "whacking" test on it: whacked the catcon a few times, no weird sounds at all.

What are your thoughts on this?

-02 sensors starting to act up?
-Exhaust leak?
-Bad oil?
-Simply a fluke?

Thanks!

Post by **SilverS70** » 28 Feb 2010, 00:09

I'd look and listen for an exhaust leak. I doubt its faulty 02 sensors if replaced with oem. See if the code returns. That said, if it is the original cat, its given 10yrs and 135k miles. Let us know how this turns out, as it seems to be a common problem recently. More people are posting p0422 code in the various volvo forums I visit as the S/V series turns 10yrs old.

Post by **FlyingVolvo** » 28 Feb 2010, 10:01

I don't really know what to listen for as far as an exhaust leak. I do have a noise though that I can't quite identify, which may be consistent with an exhaust leak sound.

It is a sorta of high-pitched squealing sound that will come and go at completely random times. Sometimes I'll hear it at idle, and it'll be the high-pitched noise going on and off constantly in about quarter-second intervals. Then instead of going on and off, it might just stay on and be loud (high-pitched squealing), then it will either go away for a while or keep doing the on-off thing.

I can't really pinpoint the origin, but it sounds like it comes from the rear of the engine (as I stand facing the front of the car) near the turbo area. When I listen under the car, it sounds like it is coming from above, again near the back of the engine.

I've been hearing this sound for over a year now, but have had a code for P0422. Does this sound like something to pursue?

Post by **Ozark Lee** » 28 Feb 2010, 10:10

You might be able to trick the second O2 sensor with a spacer but I suppose it depends on where (which state) the car is registered in. I'm not sure if the spacer trick will get you passed in CA. Some of the guys on VS use a spacer (I'm not sure what size) to trick the system after they straight pipe the cat.

All 1 of my catalytic converter problems, that was in my wife's Jeep, resulted in a total meltdown and the converter sounded like it was filled with gravel when I smacked it. It does not sound like yours has progressed to that point. Aftermarket cats are fairly cheap but most are not CA approved.

To the high pitched squeal - do you have SAS? What you describe is symptomatic of a failing SAS pump.

...Lee

Post by **FlyingVolvo** » 28 Feb 2010, 10:28

I am from California, and coincidentally I need to have a smog check no later than April! Lucky me...

As far as I know, my car does not have SAS. Is there an easy way to check?

Post by **Ozark Lee** » 28 Feb 2010, 11:25

As far as I know, my car does not have SAS. Is there an easy way to check?

At least on the 850's there is a mushroom shaped valve on the top of the exhaust manifold on SAS equipped cars. The blower motor for the SAS is down under the battery tray I think. Thankfully, none of the 850s in my fleet has SAS.

...Lee

Post by **FlyingVolvo** » 28 Feb 2010, 12:08

According to IPD, SAS cars have an additional intake on the air filter box. Mine doesn't seem to have anything like that. And so far that I've seen, 2000 models don't have it. They say if it did, it would be located under the battery. The noise really doesn't come from there. It's also been said that the noise usually goes away after the car is warmed up, but I hear this noise after a long road trip as well.

Post by **Ozark Lee** » 28 Feb 2010, 14:50

Hopefully you don't have SAS. I really know nothing about V/S series cars other than that I have seen them on the street. As I understand the system the SAS only runs for a short time after the car is started which, if you have the SAS system, the noise would quit after the car warmed up. Its purpose is to get the catalytic converter hot quickly.

...Lee

Post by **FlyingVolvo** » 20 Mar 2010, 15:45

UPDATE:

We went and did the smog test yesterday, and it passed (by a lot). All numbers were below the maximum, and in fact also significantly below the average for passing vehicles.

So I'm guessing that sort of rules out a main catalyst failure...

speedysmurf · Post by **speedysmurf** » 17 Apr 2011, 08:30

I'm hunting down a P0422 on my 2001 V70xc, I'm going to start with the rear O2 Sensor. But as for the High Pitched Squeeling sound, does it seem to happen when you are off the gas??? I had a "whistling" sound that came from the rear of the engine for a while but it would happen when I would let off the gas while driving, it ended up being a bad turbo that sucked all the oil out of the engine and ultimately resulted in replacing not only the turbo but the entire engine. wish I had fixed that one earlier!!!