How many catalytic converters?

There are three. One attaches to the front bank of cylinders near the radiator, another attaches to the rear bank of cylinders near the firewall. Those both feed into a Y pipe that goes under the floor and has the third converter in it.
The front two are the most often replaced.

My check engine light is on, had it tested twice and am being told by one place that it could be dirty gas, bad vacuum leak, or catalytic converter, treated the gas, cleared the code, drove about 40 or 50 miles and check engine light came back on... my mechanic says it is shooting a code for catalytic converter. How many catalytic converters does this car have and how do I know which one is bad? Thanks!

Hello,

There are three one at each exhaust manifold and the main cat under the car here is a guide to help you test each of them.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please run down this guide and report back.

JACOBANDNICKOLAS There are three. One attaches to the front bank of cylinders near the radiator, another attaches to the rear bank of cylinders near the firewall. Those both feed into a Y pipe that goes under the floor and has the third converter in it. The front two are the most often replaced. Who ever told you that doesn't know. Yes it carries three.

is it true that i can get a free catalytic converter if mine is messed up as long as it less than ten yrs old? i have an 05 nissan maxima.

usually emissionitems are warrantied for 80,000 miles but i don't know the timeline years wise. all you need to do is call a dealer and ask they will know...

i was recently told by a nissan dealer that i need a new catalytic converter. i have heard that these parts do not usually go bad on their own so i am wondering what can cause a catalytic converter to go bad? what should i tell the dealer to look for and what should i do from here

that's definitely true, normally failed converter is caused either by faulty oxygen sensors, dirty/faulty mass airflow (MAF) sensor or both.

Car starts and runs fine in the mornings or a one way trip to work about 20 to 30 mins 45 max, but if imidiately try to return trip car drops to about 20 to 25mph and will not go any faster rpms redlines if allowed but speed stays the same, mechanic said transmission or a backed up cat another said it could be the computer, what is causing this problem?

If the rpm is redlining, the transmission is slipping. Is the ransmisison fluid level correct and condition good?
Did you check for trouble codes?

Never investigated transmission beause, if it stops to rest for about 10 to 20 mins it runs fine for about the same amount of time

Then you should start and I would suggest getting a scan to check for trouble codes.

2001 Nissan Maxima GLE, 159,000 miles. 3.0L V6. This car has been great, but over the past few years the "Check Engine" light has come on several times. The first time I was told to run a few tanks of premium fuel through the car and that worked, the light went off and it passed emissions inspection. The following year this did not work and I had a diagnostic run that stated there was a problem with the Bank 1 catalyst system (PO420). One place said it just needed an ECM reset, according to their TSB, but the Nissan dealer said no, that was not correct, there was a new TSB (NTB00-070b) that said to replace the front tube assembly and O2 sensor. I had this work done (not at Nissan) in 9/06 for $800 and a week later the light was on again. This time apparently a PO430 code indicating a Bank 2 issue. As I'd passed emissions I waited until this year to deal with it. Now I'm hearing two different stories from two different Nissan dealers (both owned by same guy). One says I need a new Bank 2 converter, and that the code indicates it is NOT an O2 sensor issue. The other states that this car really has only one converter, the others are resonators, and that if the converter was replaced in 06 it might be an O2 sensor issue. He says you cannot tell if it is cat or O2 from diagnostics, only from function test. Looking at some manuals (wish I'd done this sooner!) I think I have an idea how this is laid out, but how can two different places have completely different ideas of the problem? Apparently the June 04 TSB said repair could go either way...reset ECM or replace front tube assembly (which appears to include cat) depending on ECM part number. Now I'm wondering if I got ripped off and ECM should have been reset, with no other work. If you could let me know definitively and objectively what might be wrong with this and best way to proceed it would be appreciated. As additional info...the car is high mileage...in poor condition...and needs about $1500 in suspension and exhaust work IN ADDITION to the above (which has been estimated at $750). PA has an emissions waiver I might be able to get if I spend $150 on repairs ($79 diagnostic goes toward that), which could be O2 sensor but one dealer says that isn't the problem so they can't do that repair. Car has been reliable and I really didn't want a new car payment but is it time to give up the ghost? I've made a donation so if you could respond ASAP I would appreciate it.

You say it needs other exhaust work? would that be broken bolts at the cylinder head? if so, the o2 sensor will get false readings from the air entering the exhaust system throught the areas where they leak. Usually the head pipes have pre-cats in them, if there are TSb's pertaining to the cats, it could very welll need them, especially if the code for bank one went away after the head pipe was replaced.