about a month ago, my check engine light came on, and i got a code for a rear bank O2 sensor... over the last couple of weeks however, the light has only been coming on in the morning when the car is really cold, and then by the middle of my drive to work, it goes off. and later in the day, when i leave work at 3-4ish, the light doesn't even come on at start-up.. any input?

 

Is it the same O2 sensor code every time it comes on?

 

yes

 

replace it?