P0431 - Porsche

P0431 code keeps popping up on my wife's Cayenne TT. "catalyst efficiency warmup bank 2" There seems to be no other issues with the vehicle.

2004 model Cayenne twin turbo, 4.5l V8. 77k on the clock.
I have changed all 8 coil packs and plugs and cleaned both MAF sensors (yes it has two) Did this in the spring of '11. This is the only engine work done.

Code popped up about a year ago and I erased it. Came back about 5 months later. Erased again and the cycle continues however, each return of the code comes back sooner with it now returning within days to hours of erasing.

Porsche forums seem to be not much help as the active DIYers are not many for this platform and most just shovel cash at a stealership. Also suggestions of fuel system cleaner as a fix and other voodoo seems rather like pissing on a brush fire.

Asked indie shop if it could be the downstream, post catalyst O2 sensor and they stated they have never sold nor had O2 sensor problems. ?? WTF? ever? He stated that the issue, 90% of the time is upstream of the catalyst. He would sell me the sensor but the cost might make me rather go in and have them dignose the problem. They have been a good source of parts but the conversation and tone kinda rubbed me the wrong way. Reason is a while back I was getting all sorts of codes and ordered 8 coil packs. He stated that it was unecessary and that he had never heard of coil pack problems. A TSB from PNA declared a fault with the coil packs and ordered the shops to replace if there were issues. It is also well documented amongst Cayenne owners that the first gen units have known coil issues. I removed all 8 packs and every one was disentegrated, literally. So I kinda take this desk jocky with a grain of salt. Sorry about the OT rant.

I am wondering if anyone has dealt with this issue on any car. I don't expect many of you to have Porsche specific experience but a car is a car is a car. Right?
I don't expect the catalyst elements to be bad and rather it be something like the O2 sensor going a bit cooky but not faulty completely.
I plan to do an oil change this weekend and will spend some quality time with the pig while doing so. Basically looking for ppotential problems.

Any help or advise would be very much appreciated in the meantime!

Fujiwara said:

Does the pig burn any oil? In a car that new I wouldn't expect a cat to be done, but it very well could be if the car has been burning oil the entire time. It's not the right solution... But an anti-fouler for spacing off the rear O2 may help a little with the interval of the codes.

Click to expand...

Does a pig roll in shit? Hell yes it does. These things drink oil at an impressive rate. Forged internals, twin snails... light weight oils need not apply. I used to average a quart every thousand miles until I switched to Rotella. Now it's about every 2k.
I have thought of the O2 extensions. it may be worth a second look??

I have suspected that. At 2500 for new cats and a large amount of work, I hope to hades not.

I am sure the previous owners used the factory fill of Mobil 0-40. Very thin and oil consumption in my first months was terrible.

Catless DP's are about 1500. Better but wow.
A new prom will need to be burned. The ECU is non reflashable. That will require me to send it off as most tuners state. 1500 to 2500 per my searches.

Net would be 500 hp and 500-550 tq. nice gains but a damn steep price.

I guess if your gonna own one of these you better pony up. sheesh.

How did I get the wife to go for this?

Why not just gut the cat on the stock pipes.

hah, only half.

If money's an issue you *could* do that and get the reflash. You still pass a visual check that way

Its a quick way to rice up a porsche.

Money isn't the issue for myself. The issue is the freakin cost for the parts. How can you justify 1500 for 2 pcs of pipe and some plate. It's just hard for me to swallow and my wife says she'll never swallow again if I start f-ing with her car like I do mine.
Umpa Lumpa's must be making those in Wonka's Weld Shop.

Not worried about inspection here, we have none. Even if we did, they could never see the primary cats without some work. They are sandwiched between the block and fenders and covered by a rather difficult to remove belly pan. The secondary cats I would think would run as a distraction.

True but still the price is too steep. I would be inclined to agree with the niche market and the fact that not many are enhancing these vehicles is the majority of the reason.

The wife? It's definitely figuratively. She would not be inclined to give up the nasty to punish me. She is just expressing her lack of desire for another car project. But I am with you on your point. I can't stand women who use sex as leverage or a weapon. Been there and done that.

Yea. She's a total cock hound. :lol:

Found these from Leistung Motorsports. Seems to be the most reasonable coupled with reputable company. They are only 850 for the pair. Combine this with a 1500 - 2000 for the ECU work and your at 25-3k. This is about the same price for quality replacement cats.

"Leistung Motorsports has developed the primary cat delete for the 955/957 (2003-2010) Cayenne Turbo and Cayenne Turbo S. The primary cat is replaced with straight through 3" downpipes.



The downpipes are handmade in Denver, Colorado. The tubing and flanges are made from 304 stainless steel with a brushed matte finish. We use a 3" 16 gauge mandrel bend tubing which mates up to the turbos and secondary cat. The flanges are 3/8 inch 304 stainless steel and were CAD desiged to match factory specs and are precision cut with a waterjet. The entire downpipe is purge tig welded (we fill the interior of the tubing as we tig weld the exterior). We incorporate stainless steel flex braid exhaust tubing, which is similar in design to the factory setup. We also include 4 O2 sensor bungs, identical to the factory setup. Please note that this unit recommends ECU tune to avoid tripping the Check Engine Light. We include OEM Porsche gasket in addition to the spark plug anti-fowlers to mitigate the chance of a Check Engine Light.



We believe this is a more complex install, however, can be a DIY project. Porsche specs this at 60 minutes per side for installation. """



Given that the turbos sit right on each exh manifold collector and those are squeezed and buried below, fender liner removal most likely will be necessary amongst a whole host of other garbage.
I am thinking this may be the best option as you have stated with excessive blow-by the problem will only resurface later. Plus a gain of moar powa!
I broke it down into layman's terms for my wife and she didn't disagree. woohoo a good sign.

I will spend time with the pig this weekend and see what she tells me.

Just as a side note, get couple of spark plug defoulers, a quick $5 part from Napa or Advanced could save you this whole problem. Just toss one of them suckers on and you will never have to worry about the rear O2 flipping a nut about emissions. I suggest this as you said you were less inclined to spend the cash on modding the Porsche.

If the cats are already fouled from burning oil then don't bother with new factory units or even hi flow units as they will just foul as well. I would say either make the problem go away with a spark plug defouler in the short term to allow you more time to figure out what you want too do, or go catless and then tune. The problem I see is that if you have that much blow by under the stock tune, then increasing the pressures and upping the power might cause more. So an AOS would be in order, or at least a catch can. I would much rather have my oil going into a can, than being burned.

Yes. defoulers, extensions, simulators, what have you, are in the mix but I want to fix the problem not just the light.
Only problem is the light on the dash telling me the code. There seems to be no other issues and this has been happening for a year, it's just getting more frequent.
If I do have to or decide to dump the pipes and go new, I definitely will not be getting ones with cats. I will use the opportunity to upgrade.
No. In the short of it, I would rather not mod this car at all. It has plenty of power with a shit ton of torque throughout the revs. But as problems present themselves I might as well take the opportunity to enhance, right?

Catch can is a very good idea. I am researching the shit out of this engine and will be also doing a thorough investigation this weekend. After the Saturday work I will know where I am headed.

Dieser Porsche ist ein alptraum zu arbiter. Dieses schwein musste von einem blinden entworfen werden.
Ich spreche kein Deutsch oft, aber wenn ich das tue ich trinke Dos Equis. lol


So after spending the afternoon under the car, I got the oil changed and took a good look see. Nothing out of the ordinary when it comes to the cats. I didn't expect anything, really, but a visual shows no corrosion or exhaust leaks. O2 sensors are there and intact. Wiring is solid and undamaged.
I did find oil in the drivers side turbo to intercooler tube. This oil was also leaking from the connection point at the intercooler which is what lead me to find the oil in the pipe. A bad o-ring is the culprit there. Checked the plumbing and a bit of oil was in there but nothing serious. Passenger side piping was dry. On these cars it seems that the drivers side plumbing are prone to collect oil however the intercooler on this side stays dry. Weird but whatever.

So what do I do? Beside removing the cat and actually looking at it, there really is no way of telling if it shot. Downstream O2 sensor could be the culprit but after a year I would think it would have failed, altogether, earlier.

So my options are as follows:

1. Replace bank 2 downstream O2 sensor and hope that's it.
2. Use an O2 extension to remedy the CEL.
3. Replace the bank two primary cat.
4. Replace both primary cats with straight pipe and tune.

My thoughts as follows:

1a. A reasonable job that may fix it. Cost would be 130-200 for the sensor.
2a. A band aid fix. Ckears the light but not the problem.
3a. Replacing this at a cost of 1083.00. This should remedy the problem but it may redevelop over time. While your there you may as well replace bank one. Total would be 2166 for both.
4a. Pipes and tune would be about $2400.00. This is a tad more than two new cats but will eliminate the possibility of the cats ever going bad. plus it brings more power to the table.

The TD04's are mounted directly to the exhaust manifold. This is probably why there may be almost zero lag and peak torque being achieved at 2250 rpms. The cats are then directly mounted to the turbo, meaning the element is directly off of the back of the turbo. All of this shit is smashed up near the block and sandwiched between the front frame rails. Even with the fender liners removed and all of the other crap in the engine bay taken out (a lot of garbage!) cat removal may prove to be very daunting and very time consuming. Why the frack could she not like the Forester XT??!!??

So what do I do? F- it! I go for the catless and tune. Along with the DP's and tune I will get rid of the secondary cats, add twin CAI's and 2 EVOms diverter valves (BPV's). I am also looking at a catch can, as well. I will have to do some research as it seems there is little info as to how to do this for this vehicle. Looks like I may have to shoot from the hip on the can setup.
Here is a link to a very similar setup. I probably wont be getting as crazy with the tune.

http://www.6speedonline.com/forums/...lt-ons-dyno-675-hp-710-tq-hd-1080p-graph.html

My plan is to do this over the Christmas break. My company shuts down between Christmas Eve and New Years. This will give me ample time and convenience.
Good thing I have triple squares and pentalobe sockets and bits.