Catalytic converter question

Hello,

after P0420 code, I think I will have to replace the catalytic converter. The error is "catalyst system efficiency below threshold bank 2".

I understand this may be also caused by faulty sensors, which I ordered - upstream and downstream, but in case the trouble persists, I want to know what I need to buy then. From what I found online, there were various converters for sale - "front", "front left", "front right" etc. Also I was unable to pin down the exact part number - the closest I got is "CA01-20-500A" and "CA20-20-500".

My question: if I understand it correctly, there are 2 cats there? Which one should I replace? Or do I need to buy more than one? The "bank 2" should be cylinder 2, correct?

Can I on basis of this "bank 2" error somehow find out which catalytic converter is faulty?


Thank you so much for any help.
 
:
Mazda CX-9 Grand Touring 2016
Check a local muffler shop. They can install new cat-cons for much less than a dealership.
 
:
2009 Mazda CX-9 GT
Without doing any testing, there is no way to know for sure what part to change. Assuuming you have a gen 1, we have 2 cats and 4 o2's. That is a lot of guessing.
 
:
2010 CX-9 GT
Hello,

after P0420 code, I think I will have to replace the catalytic converter. The error is "catalyst system efficiency below threshold bank 2".

I understand this may be also caused by faulty sensors, which I ordered - upstream and downstream, but in case the trouble persists, I want to know what I need to buy then. From what I found online, there were various converters for sale - "front", "front left", "front right" etc. Also I was unable to pin down the exact part number - the closest I got is "CA01-20-500A" and "CA20-20-500".

My question: if I understand it correctly, there are 2 cats there? Which one should I replace? Or do I need to buy more than one? The "bank 2" should be cylinder 2, correct?

Can I on basis of this "bank 2" error somehow find out which catalytic converter is faulty?


Thank you so much for any help.
Bank 1 is the side of the engine closest to the firewall. Bank 2 is the side closest to the front of the car. Each bank has a catalytic converter.

Before you start throwing parts at the car, I would check the O2 sensors on the front manifold with a voltmeter.
 
Thank you for your replies. I think changing the O2 sensors won't hurt anyway as the car has 170k on its odo. Do I assume correctly that there are just 2 sets of O2 sensors there - upstream and downstream? So for both catas the same upstream and same downstream?

The other thing - can you please tell me which catalytic converter is for the bank 2 - which part number? I understand that both are different.

Thank you guys for your help, I really appreciate it.
 
There are tools that allow shops to diagnose and pinpoint exact problems. There are pretty simple checks for the O2 sensors and they can also perform a capacity test on the cats. It may be worth your while spending a few bucks on diagnostic time at a competent shop with proper diagnostic scanners. Once you have that information you can perform the work yourself if you choose to go that route.

Firing a parts cannon at your issue can lead to a lot of wasted money.
 

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