Nissan Repair: catalytic conv brakes, mass air flow sensor, mass air flow

Question
I just got a code for the catalytic conv. car was running rough
had the mass air flow sensor replaced. runs great.
yet now this code comes up o2 sensors are all good.
what to do? how do I know it is for sure the cat?
also, brakes make grinding noise when slow stop. what couldthat be?

Answer
Hi Kelli -

Can you tell me what number the code is displaying?

have your brakes checked right away. Looks like your brake pads are worn down. Please take it to a competent mechanic. Brakes are the most common for customers to get overcharged. Replacing just the front brake pads should be around $100.

Hope this helps -
aloha
calvin