So I Went to the dealer for oil change and to get my cel checked

Code coming back is P0420

The service tech told me it's the cat (bank 3) and quoted me about $1,400


Can I Just get an aftermarket high flow cat to fix my problem or does anyone have any suggestions? Im Just trying to figure out the best route to take, I don't really want to shell out 1400 but I need to pass inspection by the end of the month.

Thanks In advance!
-Jimmy

 

replace the O2 sensor prior to replace the CAT, I had similar experience in my Accord and dealer asked for $1100 to replace the cat but in reality the 02 sensor is the problems.

 

Worth a shot, thanks man. Would anyone happen to have the part # for the 3rd cat 02 sensor?

 

^from my knowledge there is not O2 sensor on the third cat.


I have seen that code posted before, but at the moment can't remember exactly what it's for.

 

I'm doing tons of research and that looks true,bank 3 has no sensor. I'm thinking maybe the dealer lied, maybe to mislead me so I spend the money and get it fixed with them lol.

I'm thinking I'll just change the 2 sensors on the the motor bank 1 and 2

 

Maybe translation interpretation.
There are only 2 banks on the TL, but a 3 way catalytic converter.
P0420 is bank 1, firewall side, downstream sensor. This sensor tracks the cat efficiency by monitoring the exhaust after the cat.

With proper equipment, one can track the working of the O2 sensor to see if it's operating properly, but I'd replace the downstream senor (after cat) first. If that doesn't work, and the cat is deemed the problem, you can do an aftermarket install, but I don't have high hopes for inexpensive aftermarket cats working long term.

If the cat is bad, one can use 2 spark plug non foulers.
Place the first in the exhaust, then the second after the bottom is opened up so as the O2 sensor can be installed and not hit bottom, then install the O2 sensor.
I'll add, this is illegal.

 

Where can I get these spark plug non foulers?

 

so i passed inspection by using the scanner, clearing code and waiting until systems were ready and now i would like to actually fix the problem.

i purchased a used cat and O2 sensors for the rear ( bank 1 ) from a member, however it is from a 07 type S and mine is a 08 BASE.

can anyone confirm wether or not they are interchangeable? (before i spend hours tearing the car apart)

i tried searching on oemacuraparts but after a 14 hour work day everyday all these part numbers start mushing together :/

 

They will fit without an issue. Type-S has free-flowing cats vs the base model.

 

Thanks for the response! And the 02's from the type s will plug straight into the base? Same part?

 

It should without an issue.

 

Better check, the TLS downstream O2 sensor is different than the earlier year TLs.
36542-RDA-A01 SENSOR, RR. SECONDARY OXYGEN 07 - 08 TL
Plus aftermarket O2 sensor catalogs indicate that they are different.

But then again, the cats have different part numbers also.

 

I was struggling with the same problem for years as I have an 08 base TL. I asked my mechanic about the spark plug defouler trick, partcost me about $9 and no CEL light since he put the defouler in. It has been 2 years with no CEL relating to p0420. No noticeable gas difference or anything like that. It just feels nice to not see the CEL light 24/7 lol. So ask your mechanic about it and if he don't know then you got a shitty mechanic.

 

Can you elaborate on the $9 part??

 

Example:
NAPA AUTO PARTS

 

One for each plug so 6?

 

Youtubed it. Thanks

 

Yes exactly! I don't have bad gas mileage either it's just annoying to see the light pop on. I may just go that route because I'm not sure if I can put the cat and sensors I bought from a member on without any issues and my free time to screw around with it is beyond limited.

 

In a nutshell, the post cat, or downstream O2 sensor doesn't affect the fuel mileage as it's primary function is to monitor the exhaust after the cat does it's job, but, if the voltage becomes too high, caused by high oxygen content, the CEL will light indicating converter bad.

 

Does the light come on and stay on or does it go off and come back time to time?
Try clearing the code and seeing if it comes back. The bluetooth OBD readers are crucial for monitoring things like this.
Bank 1 cat is the hardest to replace.

 

x2

 

I'm having the same issue... My CEL came on about two weeks ago and it turned out to be p0420 but it went off after a few days of driving. Well I was driving to work this morning and my CEL came back on. I haven't been able to check the code yet but i'm betting it's gonna be the same code. Also it's been raining off and on for a few weeks. The cel only comes on after it's been raining. I don't know if that has anything to do with it or not. I have a 2004 TL base.