[Wgosma]

This CAT issue would lead one to conclude the dealer did not go thru the car and do a thorough inspection of its condition after acquiring the vehicle. I'd be very wary of taking ownership of this car- I presume the seller is not providing any type of warranty for the car (?)

Without knowing anything more if I was in your place I'd use this CAT issue as reason to pull the plug on the deal, now. Seems a risky buy, you don't know what other issues may crop up after you take ownership. if there is no warranty beyond the new CAT converter, you're in potentially risky situation going forward.

This situation is why it's recommended to have an independent shop do a pre-purchase inspection.

Good luck/Bill