Catalyictic converter failure

Asked by Oct 11, 2017 at 05:49 PM about the 2005 Jeep Grand Cherokee Laredo 4WD

Question type: Maintenance & Repair

6 months ago I bought my Jeep Grand
Cherokee , in the paper work the original
owner gave me the cat BANK 1 has been
replaced , when I bought it I had to replace
that same cat (bank1) now that cat I
recently I just got done 6 months ago is
failing again which has gave me a p0420
code :( my question is WHERE DO I START
to look for what's causing the same cat to
fail PLEASE thank you in advance!!!

9 Answers


Aftermarket catalytic converters do not last as long first of all. Second, this code doesn’t necessarily mean that you have a bad converter. It might be an exhaust leak. What is the temperature going into cat and coming out?

1 people found this helpful.

It's pretty apparent and the noise it makes it noticeable too, the cat has also changed color, I believe I may have an exhaust leak (I know nothing about cars) but the new muffler I put in is definitely showing signs of burns, where do I check for an exhaust leak? I have no clue how may I determine?


For burn purposes, get under car cold and start up and find puffing joints/connections that are leaking. Also louder noise can help find leak.

Really appreciate you , any other tips hints you can throw my way ??


You should also have the vehicle live data scanned, there maybe a problem with fuel trim, if it cycling way too much there could be an internal engine vacuum leak or bad or leaking injectors on one bank. HTH

1 people found this helpful.

It's killing way to much gas, LIKE unbelievably before i even thought about an exhaust leak I thought about the injectors. I need to get those checked out as I have not had or checked those myself since I've bought it

To own a jeep one should have some knowledge of how a veihical operates or have some mechanical skills don't get me wrong I love jeeps I have a really nice 96 Grand Cherikee and mine drives and runs great it's got the 5.2 which I think is the best engine of all the engines in a jeep but the jeep has its quarks they can be a pain in he but but to me the zj yj are so easy to work on

My Grand Cherokee I put 5 converters in it and no one every said why this keeps happening...Love my Jeeps, now my 08 jeep is on it's 3rd... with 325,000 miles


Was stated above get it live data scanned, a sensor could be sending a false signal, fuel trim could way off, some coolant getting in the exhaust. HTH

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