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.
 
So guys, I let the car checked and there was some leaking small tube that had something to do with air inflow or something (sorry for my lack of technicals).

They fixed it. Cleared the code. P0430 (sorry, I wrongly typed originally P0420) came back some 50 miles later. If I reset it, it comes after another 100-200 miles if driving on highways, sooner within city limits. Always P0430.

Interestingly. the shop ran emmissions tests and the car passed it okay.

So what do I do now? They didn´t install sensors I bought (one upstream and one downstream), because they tested them and they are working okay. They changed spark plugs I bought.

P0430 is meant to be the front of the car pre-cat, correct? So should I replace O2s there that I already bought for this pre-cat? If this fails, should I replace coils? I read somewhere bad coils may cause trouble as well. Or should I buy this front pre-cat? Trouble is, there are 2 cats and I don´t know which is which. Is the front one CY01-20-500A or CY01-20-600A? I don´t want to buy them both.

Any help appreciated.

Thank you!
 
:
2009 Mazda CX-9 GT
What did the shop do? Other than reset the computer? And fix a hose?

When you reset trouble codes, the emissions have to relearn things, which takes a few 100 km, and you can pass emissions testing in this condition. You still have P0430, so nothing has changed.

Sounds like you need another shop to take a look at it. A good shop can diagnose the problem rather than just reset the CEL.
 
:
2007 Mazda CX-9 Touring
What year is your car? if you have a gen 1 you should only have 2 cats total. One for bank 1 which is closest to the radiator and 1 for bank 2 by the firewall. As for the oxygen sensors you have a total of 4. You have an 1 upstream and 1 downstream for bank 1 and 1 upstream and 1 downstream for bank 2. If you are going to replace the o2 sensors i would replace all four as the other 2 will probably go in the near future. I would check the sensors though before replacing to make sure that they are bad.
 
Thank you guys for your reply.

Yes, it is 1st gen, from 2010, European version.

I am not sure about O2 sensors - would you replace it, when both certified dealership and very skilled repair shop stated they are okay? I think it will do no good, but I bought pair of them (upstream and downstream) already, so I think I may as well change them, the car has already 175k km.

@Bronco Boy Yes, the shop checked for everything and fixed the hose. There is LPG added to the car and this small hose was added then and they replaced it. Otherwise, they found nothing wrong. The car itself runs flawlessly. Also, I am not sure clearing the code would make the car pass the test. I think it is the other way around. But I may be wrong there.

Anybody knows - is the front pre-cat CY01-20-500A or CY01-20-600A?
 
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