Dear Car Talk
My 1997 Honda was stolen then found but with out the CAT so I had a mechanic replace it (Home garage) ran excellent now check engine light on an was told needs another CAT only been a year so not sure if I should replace again also leaks oil( bad) and need control arm all for my inspection-Love the car runs like a race horse 
Some advice please
Oh I can ride the bus for free Iām a senior 
Cat lasted for a year and was installed by a home mechanic. Hmmm. There is your problem. There may be other reasons the cat failed and they may not have been fixed by this āmechanic.ā
Can you post the exact code the āmechanicā told you you had? Would it be P0420 maybe??
If you want to keep this car on the road, you will need a real mechanic to correct the problems. Look here for a suggestion;
The cost may be more than its worth or you are willing to spend to keep this car running. But you always have the bus!