Federally (US) mandated minimum warranty for emissions

[John Larson]

Although the warranty does exist, it may not be what you think.  If the cat
is bad because of a rich running condition upstream, it's not covered,
although the part causing the problem may be.  If it's falling apart inside,
the mandated warranty probably won't cover it, because the breakup of the
monolith is nearly always caused by a rich condition (MAF, O2 sensor, CTS,
etc.).  Audi authorized the replacement of SOME cats on some cars, V6 90 FWD
auto trans cars, I believe, and only one side.  This campaign probably
didn't fall under the standard emissions warranty.  It might be of interest
to note that aftermarket mass outlets (like Midas) only warranty the outside
shell of the cat, something I think may violate the intent of the federal
law.  Seen many cats rust through lately?  Not I.  My 20v has eaten a number
of cats over the years, and I've probably been remiss in not solving the
real problem.  I managed to bully Midas into thinking they were liable for
the failures. (It had a failed Midas cat of the wrong diameter on it when I
bought the car.)
I've since installed a proper bolt in cat, and it remains to be seen whether
it'll hold up until the next smog check.
BTW, any emissions component failure has to actually increase the emissions
at the tailpipe (beyond the standards) to be covered.  A MAF that makes the
car run too lean, but not bad enough to cause a lean miss HC problem, won't
be covered, nor an O2 sensor that does the same thing.  HTH, John