Replaced cats, still getting CEL please help

ok guys, so I was getting the dreaded P0420 and P0430 codes on my wife's car (110k miles). To rule out other culprits, I took it in to a local mechanic to scan the voltage across the O2 sensors to make sure it wasn't them. Sure enough it wasn't, and I was told both cats are bad. Guy wanted to charge me $3k so naturally I said no thanks. Bought some OEM cats online and replaced them myself (horrible horrible job).

Anyways, CEL goes off for about a week before it returns (yes very upsetting). So I take it to autozone and the code reader spits out P2195 (bank 1 O2 sensor or MAF stuck lean) and P0171 (air/fuel mix lean on bank 1).

Does anyone have any input on this? Sounds to me like an O2 sensor issue but it's odd because when I took the car in for the voltage scan, everything looked ok sensor wise.

Appreciate any and all advice!

 

I would reset the codes and see if it comes back.

 

Those codes look familiar. I believe that I had similar codes and also the VSC TRAC fault light on my dash, which would disable the traction control. I reset the codes and used the Zero Point Calibration routine to reset the VSC TRAC system, but it continued to come back after a month or two. Replaced the O2 Sensors and the problem went away. This is a cheap and quick fix, as each O2 sensor is about $70 vs the 3k cat replacements. It seems that they can start to get weak work marginally. They also can cause other weird, seemingly unrelated problems. I am very leery about replacing items, just because a code comes up. A lot of times, the code is just a symptom of the other, real, problem.