A few months ago I noticed my CEL which had me replace my O2 sensor. Now it seems the rear cat has gone bad altogether, which is SOL for me because I'm almost to 150k on my TL.

I've been looking at repair estimates and I know the rear cat alone would push over $400, and that's not the problem. I'm assuming I would also replace the O2 sensor.

I'm reading in some places (not on this forum, none of the threads in search gave additional info) that I need to get two catalytic converter gaskets along with the cat, when it comes to parts, to be able to get the job done.

Anyone have an indication as to if this is true, and if so, what part number is it on the diagrams so I can order those too?

Gracias, amigos.

 

There is no O2 sensor on the rear cat.

IOW - make sure your problem is the 3rd cat before you go shelling out several hundred dollars.


Gaskets are item numbers 12 & 16: http://www.acuraautomotiveparts.org/...s=&view=normal



A lot of people just put a peice of straight pipe (a "test pipe" or a "race pipe") in place of the 3rd cat. ~$125 for the test pipe.

Look here for a bit of discussion on that regarding emissions: https://acurazine.com/forums/3g-tl-performance-parts-modifications-112/replacing-j-pipe-test-pipe-808199/

 

If you don't have any smog/visual checks then I would just replace it with a straight pipe. Now that's if your sure it's that specific catalytic converter.

What makes you think it's that Cat anyway?

 

The ECU has no idea what's going on with the third cat so don't worry about that unless it's plugged.

If you mean the rear bank, yes you have to use the gaskets, I prefer copper gaskets for longevity with aluminum heads and steel exhaust.

What makes you think the rear cat is bad and which 02 did you replace, the primary or secondary and which bank?

 

Good call on the rear bank, M.

I thought he meant the 3rd cat.

 

I'll have to dig through my maintenance records to see the specifics on which bank, and if it was primary or secondary, but in the meantime I can tell you that as far as I know it's the rear (not 3rd) cat since last year it was acting funny so they replaced the O2 sensor, hoping that it would solve the problem.

It did...temporarily. Now the egg smell is back again, and much more often, and when I ran the codes it was for the rear cat. I'm still going to verify that it's what I think it is (I sure don't want to drop hundreds of dollars on a part I don't need), but more than anything I want to avoid the stealership if I can. Not a problem in my case, since my TL has been out of warranty forever.

And bearcat, I sure hope you didn't really mean part #15 on the diagram...that's the muffler. Sweet hell!

 

What was the code that you got?

 

You may want to try different brands of fuel first. You might be getting sulfur in the fuel.

 

Corrected. Items #12 & #16 are the gaskets for the 3rd cat.

 

You may want to see if there is anyone that has installed high flow cats that would want to sell you there original cat. I saved all 3 of mine, but will continue to do so.

 

When I got the O2 sensor replaced last year, it gave me the following codes:

P2238 Rear Air / Fuel Ratio Sensor (Bank 1, Sensor 1)

and

P0420- Catalyst System Efficiency Below Threshold

Now it's giving me P0420 again, which I have suspected all along.


As for the sulfur in the gas, I only ever fill up at one particular Chevron gas station just down the road. I don't ever mix brands, since that can make a difference. But the CEL light has been giving me this issue for some time now and the same code comes back every time.