CAL SMOG questions (How long before a CAT goes bad?)
 

I have to SMOG my 91 Civic this year. I took it to a Test Only shop and
they told me my CAT is bad. I checked all the previous years that I had the
car Smogged and it passed with no problems. I don't know if this shop is
pulling my leg, to get a kickback from the muffler shop next door, or what.

TIA

JW