Thread: 2002 GTP replacement cat question

Hey all, I had another more general thread posted about my car a couple of weeks ago, so if this is spamming please merge them.

My car (2002 GTP) is setting a catalytic converter code and the SES light is on. Replaced rear O2 hoping that was the problem and the code went away but came back on about a day later. Mechanic is pretty sure the cat needs replaced, so before I order one I want to make sure I do it right.

Will this cat be a suitable replacement for the factory cat, and will it operate properly with the stock emissions control and not cause more codes to pop up? ZZ Performance Was going to go with the ceramic core as I believe it's what's currently in there but not positive.

Also going to replace the upstream O2 sensor just to be safe and get it all out of the way now. Any advice would be great, just want to make sure I don't screw it up.

Thanks for the responses. I will probably do the 3 inch downpipe/cat assembly both now that you mention it gtpsinc. If the car continues to set a P0420 code isn't that going to screw gas mileage? That code is a result of the emissions computer getting an improper fuel/air mix reading on the exhaust right? Won't that result in the computer leaning the car out or richening it up until it gets the right post combustion mix, or am I being stupid about this?

Alright that makes me feel more confident then. Much appreciated on the thoughtful replies, and I'll have pics of the car up as soon as weather improves. Hate Indiana winters. It was 70 two days ago and yesterday woke up to 3 inches of snow. Argh.

I can get you the part numbers for some good magnaflow cats.

They're under $100 yet they wont through a P0420.

That would be great CG. Save me the trouble of having to reprogram the PCM.

I'd suggest getting a 3" DP from a vendor.

Better fuel mileage and a little more go.

Also welding onto rusted pipes doesnt work well.

Here are the ones for 3" pipes:

MagnaFlow Catalytic Converters - 49-STATE & CANADA Catalytic Converters For Trucks, Suv's, American Muscle, Diesel, & Sport Compact Vehicles

And if you want something smaller you can try this:

MagnaFlow Catalytic Converters - 49-STATE & CANADA Catalytic Converters For Trucks, Suv's, American Muscle, Diesel, & Sport Compact Vehicles

Just to give you an example of how inexpensive they are:

Amazon.com: Magnaflow 99009HM Universal Catalytic Converter (Non CARB compliant): Automotive

With ZZP be sure to select the offroad pipe and select the add rear O2 bung for off road pipe.

Cool thanks a lot for the links bud. Will update on how things turn out.

The car has 150,000 on it and I'm not sure if/when the previous owner did anything with it's current cat. Not sure how to find out either as I'm pretty sure the carfax info is long gone now.

So I purchased a ZZP Cat and took it to the shop to have it installed, and the mechanic told me that he was afraid that it would rub on the heatshield under the car. He showed me how it fit and there was less than 1/4 inch of clearance on either side of it. It looked like one of these Amazon.com: Magnaflow 99009HM Universal Catalytic Converter (Non CARB compliant): Automotive but was from ZZP. I didn't put it on just because I didn't want to find out the hard way. What am I missing?

you could bend the heatshield so you have more room.

or buy one of the spun metallic cats.

If you can wiggle it back and forth and it doesnt hit you're okay.