Hello

I recently had my check engine light come up, and I took it into a PepBoys to scan right away. The po420 code came up which is a low efficiency in the threshold bank #1 of the catalytic converter. I hope this is just an o2 sensor or maybe the cat needs to be cleaned. Can anyone help me out with this?

 

it could be the sensors or a bad cat even possibly an exhaust leak.make sure to pinpoint the problem because emissions parts are expensive.