DEC Catalytic Converters

[john at westcoastgarage.net]

Dan DiBiase wrote:
> I'm curious as to what would cause a need for new cats on an 
> 8-year-old car....? I'm starting to look at things like this as my car 
> ages.
> I am looking at a TB change in about 15k miles and stuff like having 
> to replace the cats in a couple of years makes me nervous!
>  
> Dan D
> '04 A4 1.8Tq MT-6
> Central NJ USA
>
>
> My A6 is a 95, and early cat failures, especially the right side, were 
> well known by the time mine failed.  B4 90s had the same problem.  The 
> left went first, then the right.  These failures happened at about 10 
> years, IIRC, far beyond the warranty extension Audi offered.  We were 
> at around 200K by that time.  As someone else mentioned, cars fail for 
> numerous reasons other than age. Most prominent among those reasons is 
> rich running, but I've seen damage caused by impacts of various kinds, 
> broken welds or cracks in the body of the cat, and (occasionally) 
> damage from excessive oil consumption.  A pretty severe miss, say from 
> a dead plug or plug wire, or even a dirty injector with a bad spray 
> pattern, can eat a cat over the period of a weekend trip.
That said, I've put cats in A3 and A4 VWs at well under 100K, and the 
local dealer sells a TON of 'em.  On an OBD 2 car, that's gotta be a 
part failure rather than a running problem, because a running problem's 
gonna set a CEL far before the cat is damaged.

John