Bad cat, what're my options?

Skipping the long story about my code hunting, problem identification, total crap experience w/the stealership....my issue is that I have a bad catalytic converter on my passenger side. Car drives just fine, no issues or any difference I can tell but the P0421 code is there and will not go away and after $200+ the stealership is told me it's the cat (and the post cat o2 sensor , which I still very much doubt as we've swapped the sensors) and wants me to plop down about $2500 for fixing it all. Anyone have suggestions on what I could do? Would an aftermarket exhaust take care of this? Is there some way to bypass the cat altogether either through tuning or some other method? Any help or input would be appreciated, thanks.

What does fixing it all mean? Just replacing the catalytic converter ? Usually the problem is more upstream and fixing/replacing the cat is a bit of a temporary solution. I showed up with the intent of telling you to sprinkle pepper around your car to make kitty stay away but different cat =^_~=

I had the "stealership" replace a bad cat in the left header for free... apparently cats have an 8 or 10 year warranty (not sure which one). Its an emissions thing. Not sure your exact problem, but wouldn't hurt to ask.

that's what I tried to do, but they were nice enough to go ahead and tell me I'm out of warranty, with no chance of good will (my CPO expired last August), AFTER they charged me $200+ for diagnosis. mind you this is after I had to push my service adviser to even want to explore the issue, their 1st answer was O2 sensor , let's just replace that for $700+....anyway, like I said I don't want to get into the experience there, but they were trying to push me to buy a new cat for $1600.

Two options: 1) Ask around if anyone has a set of manifolds+cats ... People building race cars, going to aftermarket headers ... And the like. I got a set from a guy here for just the shipping. Kept them as spares, had time to ceramic coat them. They went on the car 6 months ago. B) get an aftermarket tune from softronic -- it ignores the results from the downstream O2 sensors , doesn't throw a code. It *does* still care that the sensors are plugged in, whether in the exhaust stream or tied up out of the way. And you'll unlock some more horsepower ... The gains are modest until you add an aftermarket exhaust . -PM.

Too bad this is a 987. I have a pair of 981 factory cat headers that I took off at 5K miles that I will get around to listing sooner or later. But the Fabspeed headers that I replaced them with have gone bad and I am in the process of getting Cargraphics headers installed, In my case, the first symptom was both rear O2 sensors too rich, then proceded to the front o2 sensors . Oil temperatures started rising, so I parked the car and trailered it down to BGB rather than risk the engine in a 1000 mile drive. Highway fuel mileage went from 29.5 to 24 MPG. In my case, I am pretty sure there was an exhaust leak before the converters. Either a weld let go or there was a leak at the head/flange that let too much oxygen in, causing the computer to make the mixture too rich. Although ugly, the larger welds on the Cargraphics will hold up better to the wrapped thermal environment I run my car and you can't see the welds under the wraps anyway. V6

So I actually just got a few days ago a much better explanation from the foreman at the shop who tried to give me a run down of exactly what happened. After wracking my brains for a couple days I still think I'm missing something. He said the initial P0421 (bank 2/passenger) code, after a conversion test with the PIWIS , a P2196 code emerged, which after swapping pre-cat O2 sensors showed up as a P0431 (bank 1/driver) code. So basically the final recommendation was to replace the bank 1/driver side cat in the exhaust manifold (not muffler as initially thought) as they think it's going bad (the post-cat O2 sensor was still responding actively to fuel enrichment and lean flushing). I am confounded as to how this problem which stemmed from a stubborn P0421 bank 2/passenger side code has shifted to the bank 1/driver side all of a sudden. Based on some of the feedback received thus far, I have seen some ppl selling used manifolds (which at this point I'm thinking maybe I just replace both sides). As for a softronic tune , I don't know if that'd even be the proper solution if I do indeed have a cat that's going bad?

I had a P0431 on a 06 CS it was a bad cat and it was within the 8 year or 80,000 warranty. The dealer replaced the exhaust manifold at no charge. If you are out of warranty I would either look for a used set or buy a set of aftermarket headers . Cman21

The initial code of the P0421 would be for the Cat Efficiency and usually happens from a bad or defective cat in bank 1. The other code P0431 would be the same also for bank 2. The faults can also happen from a bad valve lift error in that bank or aged post O2 sensor , yet this is uncommon. The P2196 error can happen when O2 sensors are swapped if they are not fully seated, a leak between the primary to secondary O2 sensors or bad or aged unit. You can check a cat per bank by comparing the activity of the two. Basically pull up the pre and post O2 sensors and the post o2 sensors should be less active than the primary O2 sensors when you have a proper functioning Cat. When the Cat deteriorates the post O2 sensor will become more active to the point it will read the same as the primary when there is no more cat or enough exhaust gas can flow around it. Best, Scott

If I am not mistaken there is a set of 987.1 cats on this site

If you're talking about kingD's post, I'm looking for something with a bit less mileage on them, especially at the price being asked. I did send an email out to another member who had an entire exhaust with headers listed.

Guess I should also mention that I'm not even 100% sold my cat is bad, or going bad, and if it isn't just the tight tolerances on the 06s that's responsible. There's no rattling I can hear, no weird/foul odors, and a little over a month ago after I reset the code I drove ~250 over a couple days in the mtns without it popping back on. With that said I read somewhere folks having success running some BG44K through their system so I'll give that a go this weekend since I'm going on a fairly long drive on Saturday.

Also, There are lots of 981 cats and 987.2 cats on sale on Panjo, I would not spend 2500 for new cats. Worst case, buy one of the newer 981 or 987.2 cats, then have a someone cut out the cat portion from the 981 cat and then cut out the cat section of your 987.1 manifold and put the cat it. All these cats are similar in size but measure first your diameter. I can measure mine 987.2 extra manifold I bought to convert to racing cats if you go that route... Also you can buy high flow cats from F+VD an have them welded in (200) is what my fab guy charges me... The cats themselves are 300 each. Here is the link, you have a 200 and 100 cell option. FVD Brombacher Online Shop - FVD11399920 - 100 Cell Sport Catalytic 4"(105mm) 100mm long - Tuning ? Exhaust ? Catalytics FVD Brombacher Online Shop - FVD11399921 - 200 Cell Sport Catalytic 4"(105mm) 100mm long - Tuning ? Exhaust ? Catalytics

If you cleared the code and it didn't immediately come back then you don't have a bad cat, which means your secondary O2 sensor isn't going haywire with activity or otherwise if you reset the code it would come back likely within minutes if you truly had a failed cat. You don't have your car listed in the Garage here so I cannot see what you are driving in your profile, please include that information. As you mentioned early 06 cars have tighter tolerances which Porsche later changed in an 07 ECU update, along with going to higher cel cats. You mostly likely just have one of those tight tolerance cars that occasionally get out of tolerance and throw that code. If you are outside the 8 year emissions warranty then your dealer is under no obligation to replace it for free under federal law, likewise if your CPO or extended warranty has expired then that won't help you either. I don't think you need new cats, besides if you put another set of cats on from someone else's car your ECU tune from 06 may still trip if it sees values outside what it will accept. I would either: 1) Ask Porsche to flash your ECU with the newest available ECU update for your car, there were updates in 07 and 08 and I lost track after that. or 2) Get an aftermarket ECU tune, such as Softronic , that will ignore the secondary O2 sensor readings and no longer trip the occasional check engine light due to a reading slightly out of what an 06 ECU would otherwise accept. If you do 1 and still have the code come up then I'd look at getting 07 or 08 cats to put on your 06 car (I'm assuming you have an 06) If you do 2 then I don't think you'll ever see that code again.

Interesting, I'd only been told that since it takes a certain amt of driving/miles before the DME resets or has time to readjust, it doesn't mean I'm in the clear. I have an ' 06 Cayman S with just under 58k miles, came off of CPO last August which is a shame considering what's going on now. I had an aftermarket exhaust for a couple yrs and recently took it off, so I don't know if it had anything to do w/this codes appearance at all. Your #1 suggestion is a great one, and I honestly wish I had thought of it back when my car was there at the stealership. I may call them up and inquire how much it would be to do the reflash from them. I will also look into #2 local to me as well, just in case. Thanks K-Man!

BTW with option 2 you can flash some flashes in the convenience of your own home with an Internet connection, you don't have to take it anywhere. As for having the prior aftermarket exhaust I'm assuming it was a cat back only and you always still had the stock manifold/header with integrated cats. An increase or decrease in exhaust back pressure from the aftermarket exhaust could have made the code less likely to trip vs the stock exhaust , but hard to say exactly without more evidence. It could also be an O2 sensor got dinged in the removal and reinstall process as well. Anyway should be an easy fix. Sent from my SAMSUNG -SM-G935A using Tapatalk

man things got super weird today, started the day after the DME drive cycle reset with a P0421 AND a P1530 code....cleared that, was going on a mtn drive and 50 miles later the P0421 came back...cleared it, went for 140 miles before the P0421 came back on.....cleared it, and now sitting WITHOUT the P0421 but a P2196 instead...totally confused as to what the hell is going on, going to ahead and replace the bank 1 sensor 1 O2 sensor and go from there i guess

Has anybody on here done this? I have a 2007 base Cayman with bad CATs and was considering buying high flow Magnaflow CATs and having them wielded in. Does anyone know the dimensions of the stock CATs at the fattest point? The exhaust pipe is 2.25", right? Do the CATs have to have 2.25 inlet and outlets or 2.5 to fit over the exhaust pipe? Sorry for the dumb questions. The oxy sensors are mounted before and after the CATs so they should still be in place, right? I have had resonators removed on an '03 VR6 Jetta and an '09 2.0T Jetta by the same local shop and they had to fabricate a bent pipe to replace the resonator on the 2.0T. I have been very pleased with their work on those two cars and would trust them to do the Cayman.

My experience with CATs and O2 sensors on other types of vehicles is anything that lasts over 80,000 miles is like icing on the cake especially the O2 sensor in front of the cat.

Yeah I've had two different mechanics tell me the O2 sensors are good so I'm looking into replacing the CATs

I had bought a precat O2 sensor and was going to take it in today but what do you know, ever since I ran a can of BG44K through it Sunday I haven't been able to get anything to pop up. Been driving it trying to run through the proper drive cycle and as of a couple days ago, all sensors except 1 (sec air system was still incomplete) had checked out ok to the point where I went and passed my emissions. Needless to say I'm going to see what happens, been in touch with my local shop and as soon as their PIWIS /laptop is back in shop I'll be taking it in to make sure I have the latest ECU flash, a la, post 06 flash. Glad I didn't jump the gun just yet to buy new exhaust manifolds or anything.

I ran a bottle of Guaranteed to pass emissions and then a couple weeks later a bottle of CataClean . The car felt a little more responsive and the one CEL stopped - Oxy sensor stuck rich or something. I'm still getting the catalytic warm up below threshold CEL on both banks. I might just try the BG44K, can't hurt....

This sounds familiar to what happened to my 06 a few years ago. I had a Fabspeed race exhaust on it, at one point or another the exhaust manifold was starting to crack slightly, and I was getting the same sort of codes, my mechanic welded the exhaust manifolds as a temp fix. As it persisted I was able to get Porsche replace it under the 8/80 federal emissions. They did not replace the side that had been welded, which I understand completely. I bought a used exhaust manifold with the CAT for like $250 bucks, and had my shop put it on. I removed and sold the Fabspeed exhaust , and never had the issue come back. Don't spend the money at the dealership, with all the people upgrading their exhaust there are so many of the exhaust manifolds with headers for cheap. try that before you fork over that kind of cash to the dealership.

yeah that's what I was thinking. there's a guy locally with a set but they have 50,000 miles on them, I'm thinking that's pretty high for CATs? I was also thinking about Magnaflow , they have a direct bolt in replacement for about $400 with a 5yr 50,000 mile warranty. What do you think as far as acceptable miles on a used set?

There isn't a 'bolt in' replacement for 987 cats -- they're part of the header assembly. That said, you may find a small aftermarket converter which may be welded in place of the failed stockers.

I can't say if I think there is a threshold of miles you should consider. I bought mine from a guy that builds race cars and took them off relatively young. Maybe 20000 miles. If it's close to the mileage on your car then go for it. The magnaflow sounds like a good deal too, better sound new with warranty.

The thing MagnaFlow makes for the Caymans is the header and Cat assembly and it bolts right in

I've been chasing intermittent bank 2 cat P0431 codes for the last year on my '06 CS. Dealer says it is the cat degrading ( O2 sensors are ok) and its at my discretion when to replace it since its out of emissions and CPO warranties. Their $2500 CAD estimate has kept me putting it off for as long as possible. The local indy shop recommends replacing it with an OEM cat, too. The original owner had the ECU flash and the bank 1 cat replaced under the emissions warranty years ago. The direct fit Magnaflow cat option and its price seem very attractive. Has anybody tried the Magnaflow direct fit cat for a '06 CS?

I talked to a guy in one of the carrera forums that had purchased CARB-legal cats by Magnaflow , direct bolt-on (no fab/weld/cut needed). Also had bungs for O2 sensors . He said he is very happy with them. The 5 year 50,000 mile warranty is big plus too, but has to be bought from an authorized dealer and installed at a shop for warranty to be valid. He said he bought the cats from HOTTEXHAUST.COM (free shipping, authorized dealer) and asked for a 10% discount coupon (saved over $200 for both).

While the conversation here on CATs has morphed over time, I thought I'd just point out that CAT's have a federally mandated warranty period separate from the car. Original equipment converters on new cars and light trucks are currently covered by an eight year/80,000 mile emissions warranty. Motorists can return to the new car dealer for free replacement as long as the converter is covered.

Unfortunately I didn't own my 2007 Cayman until it had 87K on it....oh well, time to start saving up for the Magnaflow bolt on header/CATs I guess....

Has anyone received and installed the direct fit magnaflow headers with 200 cell cats? If so, any pictures/feedback? This seems like a pretty cost effective way to open up the exhaust flow without spending an exorbitant amount on headers just to get high flow cats. The idea of installing 200 cell cats on stock headers is appealing to me as well. I've seen people mention this but haven't seen it completed.

I actually just had them installed a couple weeks ago. The mechanic said he really liked them and the way they were designed and that they fit perfect and installed easily. They were definitely cost effective, bought them during a Holiday 25% off sale. I've only put about 100 miles on the car since installation but I have not had any check engine lights since installation. With the bad cats I was getting a low efficiency CAT in Bank 1 and Bank 2 error like every 15 to 50 miles and I would just turn it off with a Bluetooth dongle and the Torque app. My Mechanic is a PCA member and works on a lot of Porsche racecars that they race at Sebring here in FL so he knows a good piece of gear when he sees one! Other thoughts, there is a definite smell when they are first installed but it has been fading the longer I drive it. Car seems to breathe easier and run a bit better but didn't do any before and after testing. Gas mileage seems to have improved a bit but I have only been driving around town so far, should see a bigger difference when I have to be on the highway for a while so it is a mix of highway and around town like the average was before new CATs. This week I'm having him install a CircuitWerks X-pipe with dual polished tips which should look nice and sound better too.... 2007 2.7 Cayman with 5sp and about 92K miles.

Thanks for the info! How does the sound compare?

It is hard for me to tell from inside the car. I recorded a video outside before the CAT install with stock - cold start and warm start with revs. When I get the car back Thursday it will have the x pipe and dual tips on it also. I will do a video then outside of a cold start and a warm start with revs and post it on You Tube then come on here and post a link.

Nice. Is the video up? I definitely want to get the dual tips at some point but don't want to get another T pipe.

Yes here is link - Magnaflow header/cats with CircuitWerks X-pipe and dual tips on 2007 Porsche Cayman 2.7 - YouTube I'm guessing replacing the T pipe with the X pipe has more effect on the sound and slight performance boost then just the dual tips do....

Gonna do a quick bump, 2007 Cayman S threw a left bank in-effificency code. Bought the Magnaflow direct fit. The images online vs the actual product are pretty contrasting. Has this been normal for others who have bought this cat?

Hmmm, the way I remember it mine weren't as shiny and highly polished like the pics. That being said it has been working great and well worth the money. My mechanic, who does a lot of work on people's track cars said he really like the headers as far as fitment and build quality. The place I got them also has a lot of sales so I got them for 25% off around the holidays....