Problems with aftermarket cat

[Keach]

So I recently purchased a cat from D.E.C. online and installed it. After about 50 miles the code for the cat came back triggering the check engine light. Called the distributor and they sent me another one. After putting that one on the same code came up again. Not sure if anyone knows why its not working with the OBDII when its is suppose to? The only thing I can think of is the woman said it works with cars in California (although the one I was ordering said "not for sale in California") which have different emission standards than Illinois. Although California has strictor regulations making me believe it should not trip OBDII. Has anyone dealt with this problem or one simular? It's a big headache and I have to send back two cats and still get the right one.

[DustenT]

Aftermarket cats don't work.

[mooseheadm5]

We don't sell aftermarket cats for OBDII cars at our shop for that reason. See if you can get a refund, I guess, or call them and complain like ther was no tomorrow.
-Paul

[BAD745I]

if you want a cat that will work call me @ 803-359-1044, 9-5 est. jeff

[PHL]

Have you changed your oxygen sensors? It's recommended that you do so, when putting in a new cat. I have a DEC aftermarket on my 95 OBDI 318ti, and have had no CEL since installation. Do OBDII ti's have two sensors? I think you need only change the downstream one. Not sure, as I only have one.

[DustenT]

Originally Posted by PHL

Have you changed your oxygen sensors? It's recommended that you do so, when putting in a new cat. I have a DEC aftermarket on my 95 OBDI 318ti, and have had no CEL since installation. Do OBDII ti's have two sensors? I think you need only change the downstream one. Not sure, as I only have one.

Yeah, the reason you don't have a CEL is because you don't have a sensor checking for a cat...

[Keach]

Yeah this has turned out to be the biggest hassle ever. I bought a DEC, it didnt work and still tripped the code, replaced it with another one-same problem, went to the mechanic and he said BMW doesnt list a replacement part. He ended up ordering a CATCO that is suppose to be OBDII complient. He screwed me on the price for it cause it wasnt the orignal part he said he was going to get. I'll have to call him out on that cause the part costs about $380, he charged me 900! Im sure even at list it couldnt be that much. Reguardless, the light went on yesterday and I will be taking it back again to have replaced and probably fight over the price.

[aceyx]

If your mechanic is screwing you $900 for a cat, just get one from the dealer. You KNOW it will work.

And get a new mechanic while you're at it.

[Keach]

Yeah only problem is BMW only offers refurbished for about 1,500. Cars only worth probably 5k.

[bbbmw]

I wrote a post some months back - I had gotten a DEC cat for my '97. It worked for probably a year, then I got a CEL. BavAuto sent me a new rear O2 sensor (I replaced both sensors at the same time as the cat), and that worked for about 3 more months, but the CEL is still on. I'm debating whether to try another DEC, or pay the big bucks for the BMW part.

But I didn't realize the BMW one is refurbished?? That's a killer...

[Keach]

Originally Posted by bbbmw

I wrote a post some months back - I had gotten a DEC cat for my '97. It worked for probably a year, then I got a CEL. BavAuto sent me a new rear O2 sensor (I replaced both sensors at the same time as the cat), and that worked for about 3 more months, but the CEL is still on. I'm debating whether to try another DEC, or pay the big bucks for the BMW part.

But I didn't realize the BMW one is refurbished?? That's a killer...

If I were you I wouldnt put anymore time and money into the DEC or any other aftermarket cat for that matter. Ive gone through at least 4 of them and the one on my car right now has caused the check engine light to go on. Im trying to find out if a diffent mechanic can get me a deal on an OEM part. If you hear anything different from BMW let me know. I know its expensive as hell over 1,500 bucks, but maybe they are new. It was my local mechanic that told me they are refurbished...he could be wrong. Ill post something if i hear anything that might help you out. if you get your's fixed anyway other than spending over a grand let me know.

[cooljess76]

Here's the deal. I've heard that OEM cats are remanufactured before, no biggie, they still work and come with the same warranty as a new cat. Catalytic converters utilize a monolith(core) which heats up to extreme temperatures and attracts unburnt hydrocarbons to help reduce emissions instead releasing them into the environment.

There's two types of cats. Metallic core and ceramic core. BMW and many other manufactures use semi-precious metal monoliths in their cats. In many cases, platinum is used. This is why BMW cats are so expensive. I recommend using an OEM cat, but that could be very expensive.

Any OBD2 318 or 1.9l Z3 cat should fit the 318ti, but an alternative would be to find a used OEM OBD2 cat off of a lower mileage BMW. It could be from any model. Once you aquire one, you could measure your old cat, cut the flanges off and weld them onto the new(used) cat. Basically just cut your old cat off and weld another BMW cat in place.

The problem is that it's illegal to sell used cats, so you won't be able to locate one at say the junkyard. Sometimes you could find used cats listed as "scraps for recycling" which people do to sell the precious metals out of them.

But if you go that route, you have to be careful because there's a good chance that the cat you purchase might be bad. Try to find one from the lowest mileage car possible. Good luck.

[Keach]

Originally Posted by cooljess76

Here's the deal. I've heard that OEM cats are remanufactured before, no biggie, they still work and come with the same warranty as a new cat. Catalytic converters utilize a monolith(core) which heats up to extreme temperatures and attracts unburnt hydrocarbons to help reduce emissions instead releasing them into the environment.

There's two types of cats. Metallic core and ceramic core. BMW and many other manufactures use semi-precious metal monoliths in their cats. In many cases, platinum is used. This is why BMW cats are so expensive. I recommend using an OEM cat, but that could be very expensive.

Any OBD2 318 or 1.9l Z3 cat should fit the 318ti, but an alternative would be to find a used OEM OBD2 cat off of a lower mileage BMW. It could be from any model. Once you aquire one, you could measure your old cat, cut the flanges off and weld them onto the new(used) cat. Basically just cut your old cat off and weld another BMW cat in place.


The problem is that it's illegal to sell used cats, so you won't be able to locate one at say the junkyard. Sometimes you could find used cats listed as "scraps for recycling" which people do to sell the precious metals out of them.

But if you go that route, you have to be careful because there's a good chance that the cat you purchase might be bad. Try to find one from the lowest mileage car possible. Good luck.

Thanks for your post. I actually learned the entire chemical process that takes place in a cat to make it turn harmful hydrocarbons into less harmful by products such as water and carbon dioxcide when i was in High School (interesting stuff). I am also aware that it is due to the metals, usually platinium (like you explained) needed inside the cat for this chemical reaction to take place cause the prices to be outragous. Hence the issue of people chopping them off peoples cars and melting the internals down to sell. It is just difficult for me to spend 2k on my car when the care is worth 3-4 at best. I agree that finding a low millage used one is my best option, but that is easier said than done. The only instance i can think of where someone would be willing to part with one would be if they were parting the car out. So ive had a very hard time coming across them. Thanks for mentioning that a Z3 cat might work.

[marko]

once my cat went, the guy fixing my car absolutelly refused to put an aftermarket cat on it - saying the bmw ecu will not accept it too well.

I bit the bullet - shelled out 1100 bucks & have not had a CEL related problem with my cat since (40K+ miles later).

though, you certainly want to call as many dealers as you can to get a quote - as the price from each individual dealer can vary greatly... I was quated as much as 1400 bucks for a cat (and finally found it for 1100).

Originally Posted by bbbmw

I wrote a post some months back - I had gotten a DEC cat for my '97. It worked for probably a year, then I got a CEL. BavAuto sent me a new rear O2 sensor (I replaced both sensors at the same time as the cat), and that worked for about 3 more months, but the CEL is still on. I'm debating whether to try another DEC, or pay the big bucks for the BMW part.

But I didn't realize the BMW one is refurbished?? That's a killer...

[bbbmw]

A junkyard cat (vs. junkyard dog???) could be a risky proposition, as it seems that most of the BMW cats were recalled for failure (1997 and 1998, at least). You could just be paying money for the same defective part.