Hi,
I have a 2006 Acura TL (3.2 L V6, base with Nav, not Type S) and my check engine light went on. I bought a ODB2 code reader and the Torque Android App and it says Error Code P0420- "Catalyst System Efficiency Below Threshold (Bank 1)". I need help figuring out which Oxygen sensor (hopefully not the catalytic converter) to replace. If it says Bank 1 does that mean it is one of the oxygen sensors? There is no problem with idling but I've noticed a 2 mpg drop in gas mileage. I have tightened the gas cap, reset the code and it still comes back on.
Thanks for any help I can get.
Here are test results:
Test report:
------------------
TID:$03 CID:$01
- Low sensor Voltage for switch time calculation
Min: 150
Test result value: 861
PASS
----
TID:$62 CID:$04
-
Max: 4,448
Test result value: 4,979
FAIL
----
TID:$64 CID:$04
-
Max: 4,064
Test result value: 79
PASS
----
TID:$79 CID:$01
-
Max: 34,306
Test result value: 32,757
PASS
----
TID:$7a CID:$01
-
Max: 34,306
Test result value: 32,760
PASS
----

 

no its not any of the oxygen sensors..that means your cat converter is bad and u need to change it....the post cat o2 sensor is picking up that the cat converter isnt converting the corbon monoxide into carbon dioxide well enough for emission standards causing that p0420 code

 

not so fast....... how many bad convertors have you seen? rare. I would still look at the sensors. you can swap them and see if the error code follows.

 

i have never had any of my customers come back with the CEL on and same code after i replace the cat converter for a p0420 code...i have never seen a o2 sensor cause a p0420 code

 

Hi 3RDGENTL757,
You talked about your customers-do you run an auto shop?
Thanks for replying BTW.
Regards,
mjchacko
PS: Long shot, but do you know what TID:$62 CID:$04 stands for? I understand manufacturers encrypt their codes..

 

BTW, how many sensors are there? With a V6, I have 2 banks and I know there has to be at least two per bank and one after the cat. If I knew which one to replace, I could try it-replacing 4 or more O2 sensors can get expensive. And if it's the cat, I now have a big bill waiting for me. My Acura is 7 years old and I have 78,000 miles on it-what is the warranty on a cat? A google search shows 8 year/80,000 miles-is that right? And do I have to take it to the dealership I bought it from?

 

^we have two "primary cats" after the heads, so, you'll have 4(four) 0xygen sensors. 2 for each bank.


there is no sensor on the third cat underneath the car.

 

Thanks for all the suggestions guys. I took my TL into the dealership today. He said that the P0420 error code by itself was always the cat. If it came with another code (P0135 I think he said), then it's the Oxygen sensor. Best part? He checked my VIN and confirmed that I was still under warranty and so got a free cat (Bank 1) today . FYI, depending on your make, model and year purchased, cat's have a 8 year/80,000 mile warranty. My 2006 TL was 2 months and 1500 miles inside the warranty and so didn't have to pay the $950-phew!

 

These rear cats seem to die often - mine is dying too as I get the P0420 code. It's probably because they cook from the heat back there. Unfortunately I'm close to 140k miles on my '06 so it'll be out of pocket.

 

I'm a tech at an Acura dealership here in the Hampton roads area of virginia and as soon as my wife gets off my laptop i will give you an exact answer on those values but I'm not sure off the top of my head

 

as far as thoes values go its called "MODE $06" they are on-board monitoring test that monitor the condition of the cat converter and other emissions related items(o2 sensors,egr and so on) and tell you test results base on a min. and max. value ...but this test is mainly for testing the cat. conveter

 

Hi, I just joined the group.
I have a '06 TL and on Monday I took it to AutoZone to troubleshoot a code and it happens to be this same code: P0420.
i was told to start by checking any air leaks near H02S, or to change air filters before assuming it's the catalytic converter. my car is way past the warranty since it's +179K. how do I know where to start to check for air leaks??
Thanks for any recommendations-

 

I recently got a P0420 code too. Why the hell does it seem to be common all of a sudden?

 

because all of these cars are around the same age.
catalytic converters and o2 sensors tend to die or get lazy with age.

an OEM cat is very expensive.
if it is indeed the cat, might be a time to upgrade to High flow primary cats, or even Primary-cat-deletes!

if not the cat, the 02 sensors are cheap to replace.

 

intersting now all of the sudden my check engine light just went off after 3 1/2 days... now I'm confused...
what should i do now?

 

is it the same code?

if it is, it's not a coincidence. there is a problem with the cat or the 02 sensor.

OEM cats are VERY expensive. and it would be a great time to upgrade to the Primary-cat deletes or the high flow cats from www.RV6-p.com
be sure to know the pros and cons of each before buying.

or
it might be the 02 sensor.
02 sensors can be had cheaper than cats. I would definitely try replacing the 02 sensor before i would a cat. less money spent.

 

It'll come back, don't worry... I'm going to take my car into an exhaust shop soon justn; everywhere I've been reading, a P0420 is more than likely the rear cat rather than a sensor. Judging by the service manual, it isn't easy to get to unlike the front cat.

 

oh, i read it wrong. thanks alex!!

 

You have PCD's right? Did you do the install yourself?

 

yep, I installed the PCD's 3 years ago with a friend.

any questions involving the install?

 

Yes... I don't want to get raped in labor, but I also don't feel confident that I have the proper tools/experience to get the job done. The service manual says to work from the bottom of the car, removing a driveshaft etc. Did you manage to do it from the top of the engine? How difficult was the install; how long did it take? I've been considering HFPC's since my rear cat is crapping out.

 

I had the same code not too long ago, im pretty good with my mechanic so he told me instead of paying 500$ for the cat, he just used some sort of port that attaches to the second o2 sensor which tricks the computer into thinking the exhausts have been cleaned.

it works perfectly!

 

the rear cat has to be dropped from the bottom, it's just not physically possible to take it out from the top. i remember, I laid on the ground, while my friend laid on top of the engine. he was guiding it from the top, while I pushed anything out of the way. almost like playing tetris.
and no, I did not have to disconnect the drive shaft.

the heat shield that covers the cat has to be taken off. as its physically to large to go anywhere.

 

Hey guys I just recently suffered the p0420 code! I went to honda and ordered a new carb compliant cat! The cost was about 200+60 with core exchange. Total for it was 200. Here are the part numbers i used for my 2006 Acura TL. Hopefully this information helps you guys! Heres the link to the website for reference.

http://www.oemacuraparts.com/



(catalytic converter) 18160-RCA-S00
(pre chamber gasket) 18393-SDB-A00
(gasket exhaust pipe) 18302-SP0-003

 

Also, don't forget to buy new 6 bolts for the converter unless you are planning on using the old ones. If you are decent at wrenching im sure you can do this on your own instead of going to the dealership where they price gouge you for labor!

 

Don't install it yourself. You'll definitely need at minimum 2 people. One person on bottom to pull and hold things and one person at the top to guide you and assist you on moving parts.

It might be possible to do it alone if you know exactly what you're doing.

Gotta love autozone. Change air filters to fix a P0420? Employee of the month goes to......

On a more serious note a P0420 is most likely a bad catalytic converter.

Exhaust leaks near the o2 sensor will cause a different code.

 

What are the odds its plugged up or broken (the material inside)? Is it worth getting diagnosed, or should I just have a shop install a defouler and call it a day? There's no abnormal smells out of my exhaust. There's a slight hesitation in 3rd and 4th sometimes, and 5th on the highway (can sometimes be felt as a bump, all motor mounts are good), but I think its irrelevant as the car pulls really hard still, and doesn't feel bogged/slows.

 

"Check engine" light came on. Dealership asked if flashing or car sounds different - both no. Took in for service. Mechanics checked system and got P0420 'Bank 1 Catalyst' message. He did a software update and the message disappeared from dash. If message continues, need to replace catalytic converter in order.

Advice needed: 2012 MDX. Had ongoing oil leak problem a couple years ago which shop couldn't diagnose. Then car died on windy road (!) and towed to dealership. Nothing showed up when check computer system. Car then died a year later in Oregon. Entire engine was overhauled. Acura covered the cost (except for our hotel, car rental, TIME).

If catalytic converter is issue, shouldn't this be covered under the work done above? I know nothing about cars, but know to sleuth. Thanks