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!

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]

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?

RE: CEL: Code P0421
 

Give it a quick taste, if it tastes like shit its water from the exhaust, if it tastes sweet its coolant.

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?

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.

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?

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?

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?

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.