troubleshooting P0431 CODE POPPING in my 2003 audi A4 3.0L Quattro Please help!!

[leviticus]

Engine line is on, went to autozone to fine out the code and P0431 pops up. My audi has 85k on it. I have heard that this problem arises on 3.0 quattro.
Definition:
Catalyst efficiency low-bank 2.

Explanation:
The oxygen sensors monitor the Catalytic Converters ability to store oxygen.

Probable Cause:
1- Catalytic converter defective (failure possibly due to #2, 3, or 4)
2- Engine misfire or running condition
3- Large vacuum leak
4- Engine oil leakage into exhause-valve guide seals, piston rings.

That's what the code reader said. I have no idea of what the problem is. It is giving me many possibilities.
I have many friends that knows a lot about cars and one found out through using the Vag Com is that it seems as if one of the four O2 sensors is heating up slower than normal. This has no effect on the motor or how the car runs because it has 4 of them monitoring at all times. It does however cause the light to be lit.
I don't know what to believe. Taking it to an Audi dealership would be insane because of how expensive it will be just for a check up or diagnostic check. My audi has 85k on it. I have heard that this problem arises on 3.0 quattro.
Can anyone help me out??
Anyone ever have this code pop up? IF so what did you do???

[old guy]

All of the things listed are possibilities but most likely you need to replace your bank 2 (drivers side) catalytic converter.

[Dan1969]

I know that the aft O2 sensor sometimes clears that fault, but if it doesn't that's 150 dollars down the drain. Keep in mind that the cheapest Catalytic conveter you can find is for about 390USD, so you're looking at a good chunk of change.

[leviticus]

02 sensor is worth 150usd? If it is the cat could i drive my audi without it being fixed? Cause i have been driving it for a week now and i dont really notice anything change but again i could be wrong.

[jordan_lopez]

i have the exact same code and been running it for about a year..it has no effect performance wise and wont do anything to your engine...im pretty sure its the cat..are u out of the 80,000 mile catalytic warranty?

[Dan1969]

Is mainly for emissions, but you gotta keep an eye on the cat because the cells might collapse and the cat gets red hot, causing your engine not to vent properly giving you shitty gas mileage, and other symptoms.

[leviticus]

yea i would assume that im out of 80,000 warranty since i got 85,000k on the audi. Here what i plan to do before i do anything about the cat. Replace the 02 sensor (But i don't know which one i would have to replace since there's 4 of them monitoring the cat. How would i find out which sensor is bad or do i replace all 4?). I hope replacing the 02 sensor solves the engine light being lit. If it doesnt disappear then i am going to take it somewhere where they can reset the engine light. If the engine light comes back on then i know its definately the cat. My gas mileage has been steady so far....
But what you guys think? This would be a good idea to approach this as of right now before i spend a chunk of money on the cat??

[Darwood]

Start saving some money. My light went on back in August for this. I had both cats in hand, but was waiting for warmer weather to have them replaced. One fine January morning, one cat finally decided to dislodge a nice chunk of it's guts, and partially block the exhaust. At 11:30 at night. With a 5 mile drive home. Which ended up being a 20mph drive home due to no power and fear of causing more damage. Cost me $700 at the dealer to have them installed, the O2 sensors were all fine. Your cats WILL go, it's only a question of when.

[leviticus]

Start saving some money. My light went on back in August for this. I had both cats in hand, but was waiting for warmer weather to have them replaced. One fine January morning, one cat finally decided to dislodge a nice chunk of it's guts, and partially block the exhaust. At 11:30 at night. With a 5 mile drive home. Which ended up being a 20mph drive home due to no power and fear of causing more damage. Cost me $700 at the dealer to have them installed, the O2 sensors were all fine. Your cats WILL go, it's only a question of when.

You payed $700 just install it since you already had both cats in hand?? How much did you buy the cats and where??? You also have 03 a4 3.0 quattro???

[Dan1969]

Yeah the dealer will charge an arm and a leg... and a testicle... and your first born child... Best is to find an indy shop that can do the cats.

[leviticus]

Yeah the dealer will charge an arm and a leg... and a testicle... and your first born child... Best is to find an indy shop that can do the cats.

whats an indy shop?

[road_tripper]

If you have a manual transmission, dropshipparts.com has bolt-on cats for $311 shipped. I have one (passenger side) on my 03 and it works fine.

If you screwed up and bought a tip, well, there's always the dealer :)

I drove mine for about 5000 miles with the light on... it got so plugged-up I was getting misfires on all cylinders at times.

Also, save up money for the other side, because it will need replacing in the nearish future as well.

or just sell it, in 10K miles or so you'll need to do the timing belt; check prices on that and you'll find that replacing the cat was the least of your worries!

[old guy]

whats an indy shop?

An independent repair shop rather than the dealer. Preferably one that specializes in European cars.

[Dan1969]

Our cats are not bolt on...

[leviticus]

If you have a manual transmission, dropshipparts.com has bolt-on cats for $311 shipped. I have one (passenger side) on my 03 and it works fine.

If you screwed up and bought a tip, well, there's always the dealer :)

I drove mine for about 5000 miles with the light on... it got so plugged-up I was getting misfires on all cylinders at times.

Also, save up money for the other side, because it will need replacing in the nearish future as well.

or just sell it, in 10K miles or so you'll need to do the timing belt; check prices on that and you'll find that replacing the cat was the least of your worries!

I went on dropshipparts.com and is this what i need for my problem here???
*****LEFT SIDE - WITH MANUAL TRANSMISSION - QUATTRO; 49 STATE DIRECT FIT-LEFT****
Price $ 311.77
Manufacturer Eastern Catalytic

[leviticus]

what do you mean "your" cats are bolt on???

[Dan1969]

They're NOT bolt on, meaning that cutting and welding is involved.

[leviticus]

Another question guys,
P0431 code is the driver (Left) side and P0421 code is the passenger (Right) side?
I need to know because i am preparing to buy a catalytic converter asap. And i found on already i just need to know im buying the right one. Heres the website link. Please help me out. THank you all for your help.

http://www.catalyticconverterwarehou...STERN&sup=OWN&

[leviticus]

They're NOT bolt on, meaning that cutting and welding is involved.

oh okay. How much do you think an indy shop will charge me for them to install a cat?? I mean just give me a price range??

[old guy]

You are correct. Po421 (bank 1) is the riders side cat, P0431 (bank 2) is the drivers side cat.

[leviticus]

You are correct. Po421 (bank 1) is the riders side cat, P0431 (bank 2) is the drivers side cat.

okay thanks so much for your help. Also if my bank1 is bad would it give me that code too along with P0431? I want to make sure if my other cat is okay.

[old guy]

okay thanks so much for your help. Also if my bank1 is bad would it give me that code too along with P0431? I want to make sure if my other cat is okay.

That is correct. Your bank 1 cat would give you a P0421. Unfortunately when one goes the other is usually pretty close behind.

[leviticus]

okay, that really sucks then. =(
im gonna look into all this problem and try to resolve it asap as i dont want this hitting me bad down the road.
Thanks to all that helped me out

[Darwood]

Yup, I have an '03 3.0 quattro. I think it was somewhere in the $700-750 range for both cats. The dealer quoted me about $2300 for parts and labor, so I figure I made out ok. Timing belt will run you another $2200 or so, which I also had done. I knew this was all coming when I bought it, so I was prepared. Control arms are next on the list. So I've tackled 2 out of the three heavy hitters with the 3.0. I love the car, it's had no other real issues. Other than my schizo turn signal I posted about in another thread...

[Dan1969]

I know an average price range for parts and labor is around 800-900 USD, give or take depending on the parts and the shop. I'd change both of them because as Old guy states, the second one is not far behind the first one, you'll get the P0421 pretty soon.

[garcilla]

Engine line is on, went to autozone to fine out the code and P0431 pops up. My audi has 85k on it. I have heard that this problem arises on 3.0 quattro.
Definition:
Catalyst efficiency low-bank 2.

Explanation:
The oxygen sensors monitor the Catalytic Converters ability to store oxygen.

Probable Cause:
1- Catalytic converter defective (failure possibly due to #2, 3, or 4)
2- Engine misfire or running condition
3- Large vacuum leak
4- Engine oil leakage into exhause-valve guide seals, piston rings.

That's what the code reader said. I have no idea of what the problem is. It is giving me many possibilities.
I have many friends that knows a lot about cars and one found out through using the Vag Com is that it seems as if one of the four O2 sensors is heating up slower than normal. This has no effect on the motor or how the car runs because it has 4 of them monitoring at all times. It does however cause the light to be lit.
I don't know what to believe. Taking it to an Audi dealership would be insane because of how expensive it will be just for a check up or diagnostic check. My audi has 85k on it. I have heard that this problem arises on 3.0 quattro.
Can anyone help me out??
Anyone ever have this code pop up? IF so what did you do???

Added.
I have the same issue on my 2003 A4 3.0 as well. Both close friends of mine said that it may be a faulty EGR valve or a vacuum leak on the Kombi valve located in the back of the camshaft. I'm not quiet sure if these are correct answers. Im still looking around for someone who initially had this issue expedited. Or else this will be a very expensive issue to fix if its actually the catalytic converter on bank 2.

thank you and god bless.

gil

[nelson3]

I had P0431, P0421, and P0122 (i think)
I still have 431, however, to fix the other 2, I cleaned out the Throttle body and Mass Air flow Sensor. still have one code left. I'm going to check for leaks first then see if i'll have to change the O2 sensors. cata is last resort....i'm also 30 days past my registration...

2003 Audi A4 Quattro 3.0L V6