1999 ml 320 sensor
 

Help, my car will not pass smog. I need to replace bank 1 sensor 2 oxygen sensor. The car runs fine but the check engine light will come on every so often then go out. The question is where is this sensor? My guess is the downstream sensor but which is bank #1. Left side or right side? Does anyone out there know? Thanks John

Found it. Bank 1 sensor #2 is the right rear sensor. Anyone else who runs into this will now know. John