Get the emissions test from the seller, definitely. I suspect it's unlikely it actually needs a cat but the e-test will tell you for sure one way or the other. Like I said, our Taco threw this code early on and it passed the e-test I got when I sold it by the fast track criteria, it was super clean. It was either the octane thing I think since I didn't do much else other than drive it, changed the air filter, change the oil.
'91 Pickup - Imelda
'08 Tacoma TRD - Donna