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  #1  
Old 07-24-2007, 03:10 PM
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Default CEL: Code P0421

OK. Went to Autozone to pull up the codes for my CEL which has be on for about 2 weeks now. The code is: P0421.

The small printout that I got from Autozone says this:
The PCM has determined that the warm up catalyst efficiency for bank 1 is below threshold for the current engine operating conditions. (Bank 1 identifies the location of cylinder #1, while bank 2 identifies the cylinders on the opposite bank).

I did a quick search on this and found out that it could be my O2 sensors. I am going in for my 50,000 mile service this weekend and I want to know if this will be fixed by an Audi recall according to tech bulletin C260503 (got this from AW forums). I do not have a warranty on my car and I don't want to pay the dealer if I don't have to. Does anybody have a pdf of this tech bulletin or can I find it online somewhere?

Is there a cheap fix to this problem?

Thanks!

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  #2  
Old 07-24-2007, 04:38 PM
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Default RE: CEL: Code P0421

Here is what i got from the factory repair manual.
P0421= Warm Up Catalyst Efficiency Below Threshold Bank 1
Its just a fancy way of saying you need a cat converter on the passenger's side, which on a 3.0L, is beyond a pain in the a**! Plus the cat costs over $1,000 alone.
The good news is you have less than 80 thousand miles so federal emmisions warranty will cover it free of charge so grab a beer and smile.[8D]
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Old 07-24-2007, 05:03 PM
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Default RE: CEL: Code P0421

Thanks auditech!

I have been noticing for the past month or so that my car leaks under the passenger side just behind and to the left of the passenger side lower control arm and also along the exhaust pipe on the passenger side. The texture of the leaking liquid is not oily, it feels more watery. Do you think this has anything to do with the bad cat converter? Or is this a completetly different problem that I have to take care of seperately?
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Old 07-24-2007, 05:21 PM
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Default RE: CEL: Code P0421

Give it a quick taste, if it tastes like **** its water from the exhaust, if it tastes sweet its coolant.
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Old 07-24-2007, 05:38 PM
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Default RE: CEL: Code P0421

Are you serious? It won't make me sick?

Anyway, does one mean better than the other...as in, if it tastes like water it is ok? But if it is sweet/coolant, the cat converter is broke?


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Old 07-24-2007, 05:43 PM
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Default RE: CEL: Code P0421

Nah, im not telling you to drink it LOL.
As for the water the cats/connetor clamps tend to leak water on our exhaust systems when they get older for some reason, but it should be better after the cat replacment.
If its coolant, take the rear engine over off and stick a flash light down there behind the motor and see if you can see red crusty looking stuff coming off the rear coolant crossover pipe.
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Old 07-24-2007, 10:48 PM
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Default RE: CEL: Code P0421

OK, I looked under the car after it was sitting for a few hours and I could still see very small puddles and wet patches under the car on the pavement which means it did not evaporate (so I am guessing it was not water), though it had stopped dripping.

Also the underside of the car has that wet look like an oil leak. I do not have a jack to raise up my car to look under it or into the back of the engine from the bottom (or did u ask me to look behind the engine by popping the hood?). Is there anything you guys can suggest based on the symptoms I described?
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Old 07-24-2007, 11:49 PM
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Default RE: CEL: Code P0421

Yeah, pop the hood and take off the rear engine cover, and look down at the back of the engine.
If you see red dried up coolant everywhere on the cross over pipe thats where its leaking.
Are any of your fluids low? P/S, coolant, oil?
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  #9  
Old 07-25-2007, 10:44 PM
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Default RE: CEL: Code P0421

I looked behind the engine, but I didn't get a good look because I didn't have a flash light. Anyway, it looked real dirty, so it could be that the coolant is leaking, though my coolant level doesn't look low or anything.

Coming back to the check engine light, I have had a chance to do some research online and it looks like this error code P0421 was a common problem with the 2.8s. There was a factory 'suggested' service bulletin (called IC service action that came out in July 2005) that was basically a reflash of the ECU because the cat efficiency thresholds were set too high. A lot of people have said that their CELs went away after doing this. Do you think the dealer will do this ECU reflash on my 3.0 for free?

What if he tells me that the cats are not bad and only the oxygen sensors need replacing? What kinda money would I be looking at to change the O2 sensors?
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Old 07-25-2007, 10:51 PM
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Default RE: CEL: Code P0421

Un-fortunately the re-flash only applies to the 2.7T, 2.8L and 4.2L engines.
The 3.0L cats have to be replaced as it stands right now, but don't worry about it, its free from the federal emmisions warranty.
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  #11  
Old 07-25-2007, 11:02 PM
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Default RE: CEL: Code P0421

Auditech, how sure are you that it is my catalytic converter? From what I have read, very rarely do cats go bad especially at only 52k miles. Isn't there a possibility that my oxygen sensors have gone bad and are throwing up these codes?

I am asking you this because though the cats might be covered under the federal 8y/80k warranty, the oxygen sensors are most probably not covered. I am a bit worried about the cost that might be involved in replacing the O2 sensors.
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Old 07-25-2007, 11:27 PM
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Default RE: CEL: Code P0421

There is about a 5% chance of the O2 sensors being bad with that fault code, trust me its the cats, replaced over 100 3.0L cats in about 3 years and about 2 O2 sensors for that fault code.
It says in the manual if you have that code to replace the cat converters first, then diag any other problems that could occur.
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  #13  
Old 07-25-2007, 11:33 PM
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Default RE: CEL: Code P0421

Do you think that the the dealer should replace both cat converters? I know if one is going, the other one can't be too far behind. Then again, I did get only error code P0421 (which I think is Bank 1 - passenger side). I did not get P0431 (Bank 2 - driver side) error, which means the dealer could technically refuse to replace the second cat.

Any thoughts on how the dealer might proceed with this? Did you had to deal with a situation like this?
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Old 07-25-2007, 11:36 PM
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Default RE: CEL: Code P0421

By law they can't replace the other cat converter without the fault code, but your're right the other one probably will fail sometime in the future.
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  #15  
Old 07-27-2007, 01:18 PM
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Default RE: CEL: Code P0421

Here are some pictures from under my car where it leaks. Just wondering if you can tell me what I am looking at here. Is this serious? Since I am going in for my service tomorrow, I might as well try to get this fixed.

Click the image to open in full size.


Click the image to open in full size.

http://i199.photobucket.com/albums/a...e/IMG_0479.jpg
http://i199.photobucket.com/albums/a...e/IMG_0481.jpg

Just figured out how to embed pictures in a post.........I had to try it in one of my posts


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Old 07-27-2007, 03:41 PM
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Default RE: CEL: Code P0421

[sm=icon_rofl.gif]Ha hait looks like its just water. On the passenger's side right? Been using you A/C lately?
Thats exactly where the drain for the evaporator drips out under the vehicle.
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  #17  
Old 07-29-2007, 03:28 AM
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Default RE: CEL: Code P0421

Took my car to the dealer today. He said the procedure they follow for the cat convertor error code is this - they clear the code the first time. If the check engine light comes back on again, then they go in and replace the cats under the federal warranty. So the dealer cleared the code and guess what, after driving around the city today, it came back on again. I guess I will need the cats replaced after all. I hope I can convince them to replace both cats even though there is no code for bank 2.
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  #18  
Old 07-29-2007, 02:09 PM
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Default RE: CEL: Code P0421

Ha ha, erase the code first huh? Thats funny, that just tells you how much they don't wanna do the cat converters on a 3.0L.
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  #19  
Old 09-25-2007, 11:41 PM
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Default RE: CEL: Code P0421

Just to give this one a closure in case anyone is interested, the CEL came back on a couple of days after the dealer had cleared it. It was the same code P0421. Today the dealer replaced the faulty catalytic convertor under the federal 8 year/80,000 miles warranty. He also said that they cannot replace the other cat because it did not throw out any fault codes and he will be liable to Audi if he replaced a part that does not need replacing. Oh well.....I am not complaining. At least I don't have the annoying CEL staring at me anymore. Thanks auditech79!
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  #20  
Old 09-28-2007, 01:27 AM
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Default RE: CEL: Code P0421

good news, free cat!

I had that code on my old 2.8 and it was an O2 sensor. I was worried it was the cat as I did not know about any emission warranty then
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Old 09-28-2007, 01:27 AM
 
 
 
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02, a4, a6, audi, bank, catalyst, cel, code, denver, effeciancy, emission, error, p0421, po421, test


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