paully

I am buying a silver 2002 S4 this weekend and the VIN check confirms its a one owner, has no dents and is really in prime shape. It only has 99K miles, and has reciepts for recent tires, timing belt, brakes including rotors and a few other things. He is a trustworthy guy, I know him threw friends but I know this forum has talked about this error code but I am very non-mechanical and I am just trying to evaluate my cost and risk with this. He advertised it for $6K but said he would take $4k because he needs it out of his garage.

Here is what he says, "Check engine light goes on and off periodically. Just passed admissions 5 weeks ago and the light was off but now it is back on. The code that get tripped is P0421 and P0431 -bad-cat. I have not modded the car in any way, it has been serviced at the dealer. Most people just put a spacer with there O2 sensor to the code off but I have not done that.

So I am sure this is a common question but it isn't clear to me if I should be planning on $2K repair for this or if it's $200. This car is nice, he is being fully transparent. I should also mention that he said there is a light showing that a headlight is out, but both do work and he also say's that the back right brake light isn't working and it doesn't appear to be the bulb.

So, should I be sweating? Any help you can give me in terms of estimating repair cost would be appreciated.

paully

BTW, I am flying to buy this car in Portland and driving it back to Boise on Saturday, not sure if this error code would be an issue for a 7.5 hour drive?

wilson94t

The codes indicate that the 02 sensors are not reading within defined limits. The car may pollute more than it should but there should not be a mechanical issue. Still, you should not drive too hard in a car that you don't know, especially at higher elevations.

FWIW, A typical mechanic response to these codes is to replace cats.

Since you're new to the car, you may want to read up.
https://www.audiworld.com/forums/s4-...00-s4-2877589/

massboykie

Three more!

http://www.vaglinks.com/Docs/Audi/B5...Newbie_FAQ.pdf
http://www.vaglinks.com/Docs/Audi/B5...uyersguide.pdf
http://www.vaglinks.com/Docs/Audi/C5...uying_Tips.pdf

Cheers
Massboykie