Can someone tell me why the upstream o2 sensor are way more expensive than the downstream sensors? Are the not the same? can some one explaine the bank location to me.\?

 

The cylinders are numbered like this



Bank 1 is the passenger side where cylinder 1 is

Bank 2 is the driver's side where cylinder 2 is.




BTW this standard is not universal and most ford and GM motors count the cylinders in a row front to back.

 

On the early models price would be about the same,on mid 04 and up the upstream sensors are referred to as Air-Fuel ratio sensors which are a bit different than O2 sensors which would explain the price difference.

 

Wide-band O2 sensors versus narrow-band O2 sensors.