Cat Test Help

On My 2000 jeep cherokee sport 4.0 auto. This xj has 76,000 on it it is under warranty until 80,000mi.......i suspect the cat converter is on its way out....do to the fact that slight loss in performance, occational smell from cat, temp creeping up while idling for long periods....It passed its recent inspection for NYS and no trouble codes are present.

Should i just go ahead and replace the cat myself with aftermarket cat or have the dealer test it and replace if it is bad ??? What test can they perform on it and what spec..do they use to determine need for replacement?? If it is still within spec and on its way out do you think they will or will not replace it.???

The dealer charge's 42.00 to test if it is NOT bad... (Waste of money)
If it IS bad it will cost me nothing and IS covered under MY warranty.

Maybe some of you dealer guys can help?? .......Thanks

Your cat is covered 8/80 federal emission warr. However, you'll have to prove you claim of "slight performance loss". Is it rattling inside? If it's damaged in anyway (dented), you'll be on your own. Most dealers have equipment to test, but it would be a gamble of your $42. I was a service manager for a Lincoln-Mercury/Kia dealership.

heres how they will probably test it: #1 They will use the scanner to see if it has any codes for a cat failure, it would be code #P0420 probably.If so, you get free cat, if not they take your money and maybe try to sell you a tune up or something.Try hitting it when its cold with a rubber mallet or a gloved hand to see if it rattles.rattling means the guts are all cracked apart and its no good. if youre gonna take it to the dealer,ask them to make sure there are no recalls before you have them check it and possibly waste your $ because some jeeps have cat recalls. anyways the best way (the way the PCM does it) to check the cat's efficiency is to look at the data on the scan tool. Look at th downsteam Oxygen sensor .In this case it will probably be labeled as HO2SB1S2 or HO2SB2S2. Thats: Heated Oxygen (O2)Sensor Bank1 Sensor2, or Heated Oxygen Sensor Bank2 Sensor 2. Iam pretty sure your jeep it will be called HO2SB1S2. Anyways you have to watch the voltage output of this sensor with the scan tool and see what its doing. A steady fixed voltage of .500-.900 V is normal and that means the cat is working.The exhaust is being chemically changed. A fluctuating voltage back and forth from low(.100V) to high (.900V) means the exhaust is flowing straight through the cat without being chemically changed, meaning bad cat.the voltage numbers are just approx. what really matters is wether or not the voltage is "rolling". Rolling = bad cat. Fixed= OK cat . BTW the "upstream" o2 sensors are always supposed to be rolling. That would be either B1S1 or B2S1, always ending with sensor 1.Also, the tests should be done at about 2000 RPM, hope that helps- Aaron :yap:

Thanks all advice Defenitly does help

You should have recieved notification from DaimlerChrysler about a recall (RC-8591-00 / RC-8592-00) "Catalyst Monitor Does Not Illuminate MIL or set a fault code". A reflash of the PCM is performed and the catalyst is checked, if it is rattling it usually gets replaced but I'm not positive on replacement for that model year b/c '00 has the 2 cats in the manifold and I havn't done the recall on one of those yet, just the older style exhaust. If you havn't gotten a letter, go to your dealer and ask about the recall, they should be able to help you. If you want I can email you the recall info from DealerConnect.