I have a 2015 QX60 with both P0158 and P0057 codes which indicate a problem with oxygen sensor 2 bank 2. I have read that this is after the catalytic converter but I just crawled under the car and don't see it. Where is it at?
You’re lucky, bank 2 oxygen sensors are easy to access compared to bank 1. Bank 2 pre-cat sensor is in front of the engine (can be seen with the hood up), and the cat (short/fat) is a short distance front the 1st sensor mounted vertically. The 2nd sensor is right after the cat and can be seen under the car, between the front tires as it comes vertically down, bends 90 degrees then joins with bank 1. The sensor should be right before the last bend before going horizontal.