2 dead cats?

**2kSSnTX** · 11-26-2006, 08:00 PM

I have a 2000 ls1 with 85k miles, no mods. My SES recently came on and I brought it to autozone for a test. I showed 2 codes and they were: P0420 and P0430.
So they think my cats went out. So why would they both go out at the same exact time?

If my cats are in fact bad, This might be a good time for a lil upgrade?

I've read that random makes good replacement cats, but i was thinking of maybe another mufler too. I don't want to spend money on headers, I want to keep my stock tips, and I want it to be stock loud or slightly louder and quiet at idle. I mainly want more power.

What i'm not sure about is if i need a new y pipe or x pipe or whatever. And correct me if i'm wrong but a catback is everything after the rear axle, including the mufler? Can the local mufler shop meet my needs? Maybe a trusted national company?

**Too Fast** · 11-27-2006, 03:04 AM

Too bad about your cats. They did have an 8 yr/80k federal warranty. Both mine had the code and I got them free at the dealer last summer. Just because they fail efficiency does not mean they are plugged. Mine were not, the car was running 105-107 at the 1/4 at the time.
I have heard good things about the Random cats.
Also, I went to a muffler shop and had them only swap my muffler (a Midas Ravin') and keep my stock tips. Sounded good. No highway droan, even now that I have the Hooker LT and ORY. A catback is everything after where the y-pipe joins the single tube back to the muffler, about halfway under your car, not after the axle.

**Danger731** · 11-27-2006, 03:13 AM

I thought cats where 7 year federal emissions warantee ?

**2kSSnTX** · 11-27-2006, 04:02 AM

so to get noticeable power increase i can just replace my cats an mufler and keep all my pipeing?

**Wesman** · 11-27-2006, 06:22 AM

Originally Posted by 2kSSnTX

so to get noticeable power increase i can just replace my cats an mufler and keep all my pipeing?

The stock exhaust is pretty restrictive and very mild sounding. For the best gains (without changing too much or spending a ton of $$) I'd install high flow cats and invest in an inexpensive catback exhaust. That right there will give you a nice bump in both power and sound.

**TARZAN** · 11-27-2006, 08:29 AM

I work at AutoZone, and it most likely threw an o2 sensor code, and they're trying to sell you cats....Because they cost ALOT.....

If you don't have emissions, just cut them off.

-Will

**2kSSnTX** · 11-27-2006, 08:53 AM

where are the 02 sensors located? Could i buy one and see if the code goes away then return it if it doesn't? lol

**2kSSnTX** · 11-27-2006, 09:00 AM

Originally Posted by Wesman

The stock exhaust is pretty restrictive and very mild sounding. For the best gains (without changing too much or spending a ton of $$) I'd install high flow cats and invest in an inexpensive catback exhaust. That right there will give you a nice bump in both power and sound.

would i still get a performance boost by just replacing the cats with high flow cats and just swaping out the mufler, or would i get more power from a whole new catback?

**FantaZGuy28** · 11-27-2006, 09:27 AM

Originally Posted by 2kSSnTX

where are the 02 sensors located? Could i buy one and see if the code goes away then return it if it doesn't? lol

There are 2 sets of O2's, the front and rear. The front are located on the manifolds and the rear are located behind the cats. So if your showing codes for below threshold or some bs like that then its either your cats or rear O2's. Since both banks are reading it could be either the cats or O2's. Try replacing one of the O2's(since they are around $100) and see if it only throws one code. If not then you know its the cats and what I did when I was in the same situation as you was gut the cats.

**Too Fast** · 11-27-2006, 12:43 PM

Originally Posted by FantaZGuy28

There are 2 sets of O2's, the front and rear. The front are located on the manifolds and the rear are located behind the cats. So if your showing codes for below threshold or some bs like that then its either your cats or rear O2's. Since both banks are reading it could be either the cats or O2's. Try replacing one of the O2's(since they are around $100) and see if it only throws one code. If not then you know its the cats and what I did when I was in the same situation as you was gut the cats.

Someone told you wrong. 99.5% of the time if you have a P0420 and/or P0430 code it is the catalyst efficiency failure. Not necessarily plugged, just not cleaning the emissions per what the Feds want. I am paid to check these codes where I work, and I have never had a cat. eff. code from a bad O2 sensor. The PCM has to verify the O2s before it can check for cat. effic. first. You could gut the cats and get rear 02 sims to fool the PCM.

The warranty booklet explains that the PCM and catalytic convertors have a 8 year/80k warranty, replaced no charge at the dealer, if that is the code

.

For better sound and flow, buy the aftermarket convertors and a cat-back exhaust. And, get a lid. You will then see an improvement on 0-60 and 1/4!

**2kSSnTX** · 11-27-2006, 01:24 PM

Originally Posted by Too Fast

For better sound and flow, buy the aftermarket convertors and a cat-back exhaust. And, get a lid. You will then see an improvement on 0-60 and 1/4!

What do u mean by "lid" ? Will I get the same performace by just replacing the mufler insted of a whole new catback?

**texinteg** · 11-27-2006, 01:38 PM

Well if it is your cats take it to the dealer as it is now covered by a 10 year 120k mile warranty.

**2kSSnTX** · 11-27-2006, 01:40 PM

Originally Posted by texinteg

Well if it is your cats take it to the dealer as it is now covered by a 10 year 120k mile warranty.

Where did you get this information, and when did this go into effect?

**2001NBMZ28** · 11-27-2006, 01:47 PM

Originally Posted by texinteg

Well if it is your cats take it to the dealer as it is now covered by a 10 year 120k mile warranty.

Where did you find out about that? Sure? Only thing I've seen in writing is 8yrs/80K under the federal emissions warranty.

**oneBADDz** · 11-27-2006, 01:53 PM

The cat warranty length and mileage is different in cali than in every other state. Don't remember which is which, but you are both right to an extent

**2001NBMZ28** · 11-27-2006, 02:26 PM

I've seen posts from CA guys saying they were told 7yrs/70K by dealerships - which is LESS than the federal emissions warranty, never understood that. Think that's wrong, supposed to be a federal warranty. IMO since cats are mandated and supposed to be all that great for the enviornment they ought to be warranted for the life of the car, regardless of mileage, or exempt after 10 yrs/120K.

**Too Fast** · 11-27-2006, 03:50 PM

Originally Posted by 2kSSnTX

What do u mean by "lid" ? Will I get the same performace by just replacing the mufler insted of a whole new catback?

"Lid" is a different top air box lid. Many vendors sell them, check the archives. A lid and a cat back exhaust well get you almost 20 HP. Lid alone is worth 10 at full throttle. The factory top lid is restrictive and quiet. See the baffles on each side on the stock setup? That equals noise reduction and less efficient airflow. I have no pictures to show you, but check other threads, they may have a picture.

**2002 NHRA TA** · 11-28-2006, 01:34 PM

You Can Always Heat Check The Cats To See If They Are Bad. There Should Be A 50+ Degree Diff From Front To Back. You Would Like To See 100 To 150 Degree Diff. I Have Not Seen To Many O2 Sensors Though P0420 And P0430 Codes. But If The Converters Check Out Ok It Could Be The O2s Or A Program Problem In The Computer. I Would Also Suggest To Change The O2s When You Change The Cats.

**Wesman** · 11-28-2006, 07:20 PM

Originally Posted by 2kSSnTX

What do u mean by "lid" ? Will I get the same performace by just replacing the mufler insted of a whole new catback?

"Lid" is the air intake box on the front of the engine. The stock air box is restrictive and quiet, replacing it with a lid will give you a nice sound as well as a good bump in power.

You may get a small gain from changing the muffler, but not nearly as much as you will get from installing a new catback exhaust. Considering a good Flowmaster muffler is $100, and you have to most likely cut and weld it in, you're better off just getting a full catback exhaust with muffler for ~$300-$400.