98 Z3 Catalytic Repair Question

I own a 1998 2.8 Z3 and recently found out my catalytic converter went bad. The car only has 45,000 miles on it. You can hear the rattle and it feels like it has lost power. I live in CA and I was given an estimate of $1800 (which sounds ridiculously high, even for a dealership). I am wondering if there are any other solutions, as I am very skeptical to paying that much. Thank you.

You can go aftermarket but you have to make sure it's CA CARB specification.

Do you have any suggestions for an aftermarket part? I'm looking at a Magnaflow one, and it is CA certified.

If you ask/look around, you may be able to find someone with a non-CA car that has swapped to straight pipes and just buy their mid-pipe with cats installed. With our cars, it seems like stock exhaust parts are hanging up in everyone's garage.

I'm not sure if it's only florida but the cats have a 70k mile warranty, not sure if there is a time frame, but if there is I think it's 10 years.

Reading this, you refer to Cats (plural) Does the US spec Z3 have one Cat per three cylinders? The attached picture shows the UK spec 2.8 with one Cat.

I have a low frequency rattle when I tap the Cat, or when accelerating. The lower exhaust clamp (11 in picture) had fallen off and resulted in a high frequency metallic sounding rattle, which has gone now I've replaced the clamp. I don't know if the Cat has been damaged by the vibration, but I was going to see if the rattle affects emissions.

CA law: Cats are warrantied for 80k...bring it back to dealer and tell'em to replace it.

Edit: 8yrs/80k miles on Cat Law.

If you just need a new cat, I can recommended an aftermarket if you're in socal.

I'm in the UK and not familiar with what you refer to as CA law, or whether it applies to UK too.

If someone is running without a cat anywhere in the US, they are in violation of Federal law. $2500 fine and possibly criminal penalties.

The EPA rules an this are LAWS not regulations.

Originally Posted by npham858

I own a 1998 2.8 Z3 and recently found out my catalytic converter went bad. The car only has 45,000 miles on it. You can hear the rattle and it feels like it has lost power. I live in CA and I was given an estimate of $1800 (which sounds ridiculously high, even for a dealership). I am wondering if there are any other solutions, as I am very skeptical to paying that much. Thank you.

I have a 1998 2.8 and just replaced the cat in it at 27K miles. I don't take the car to a dealer, but to a good aftermarket shop instead. The cat installed cost $2100 for a genuine BMW cat. The owner of the shop said he has had problems with the aftermarket cats causing the engine light to come on after a while. If you get one, I'd be interested in your results with the engine light.

Mine lost power, wouldn't rev above 3K, and would not accelerate. The PO had hit a cinder block in the road and you could see the trail of dents from the oil pan to the rear axle. It hit the cat and caused the honeycomb inside to collapse, blocking the exhaust.

Good luck with the repair.

~mike

I went with the 50 state, as opposed to 49 state. I am not in California but I read and heard that they are more reliable and probably would not throw a CEL code.

I went with a Benchmark unit, made by DEC. Listed as high flow unit, it looks like the original except for the shape of the converter section. Fits well, proper clamping area for exhaust clamps, good welds and lighter weight.

List price about $650 but got it online for $500 with coupons and free shipping. Make sure you get what you want because shipping back a catalytic converter exhaust is expensive!

No codes related to exhaust or oxygen sensors since it has been installed.