i got a bad oxygen sensor and i need to replace it. The question i have is the bank 1 sens1 is $130 and the bank 2 sens1 is $80. Is there a difference? as far as i know there is a difference between pre and post cat sensors but a pre cat sensor is a pre cat sensor, no? plugs are the same. I actually have my bank 1 and bank 2 switched right now and all it did is switch the cel from bank 1 to bank 2.

 

Not sure where you are getting your price list from, but they are within $3 of each other (parts 9 and 10):

http://www.acurapartswarehouse.com/P...=4334%20382545

 

Usually price is just the difference in the length of the wire, but aftermarket suppliers list upstream front and rear (bank1-2) same number, e.g. NTK, Walker, but Bosch lists two different numbers, one with a wire length of 11.4" and the other 21.7".
If you look at Rock Auto, you can even get an upstream sensor from ACDELCO Part # 2131542 for $271.79. Rediculous in that AC Delco doesn't even produce the parts themselves.