Hey folks, got a question for someone sharper than myself:

I’ve got a 2013 Fit with 196K on it. Treated me pretty well thus far, had a funky misfiring problem earlier this year but that was fixed with a valve adjustment.
Noticed over the past year that my mileage was dropping off slightly, down 2 or 3 MPG, and then recently the CEL turned on. Pulled the code and found it to be a code for the Bank 1 Sensor 2 O2 sensor. Cleared the code and drove for a few weeks before the CEL came back on, this time a P0420 Catalyst System Efficiency Below Threshold Bank 1. Cleared that, drove a couple days, had it come back on, and found it again to be the P0420.
My researching online seems to suggest that this is usually means a new cat is needed, but I’d love to make darn sure before buying one. Would a bad 02 sensor possibly result in the P0420 as well? Anybody know of any way to tell which part is bad? Any advice would be much appreciated, I’d love to avoid buying a new cat if possible.
Thanks!

 

You could remove each O2 sensor and check them with a Volt-Ohm meter. There are vids on YuTube. Seems like testing the O2 sensors first would be worth it before spending $$$ for a new cat.