P0420 - 05 Jeep Liberty 3.7

[HoosierJeeper]

Got this code tonight on my Liberty. It’s an 05 with 229k miles. Looks like it’s for the bank 1 cat being below efficiency. Where to start? I’ve read that it automatically means a bad cat since to set that code both O2 sensors have to be working, but also have read the contrary. All the O2 sensors are factory except the bank one downstream, I replaced that with a factory one probably 8 years ago. No drive ability issues or change in MPG. Where should I start? Thanks!

 

[zrxkawboy]

If you don't have any exhaust system leaks, it is most likely the cat.

 

[Vitamin Yoda]

Try some spacers before you do anything. If you eventually get aftermarket cats, you might need to use spacers anyway.