what is the difference between the up stream and down stream sensor? and are they basicly the same sensor?

 

Upstream sensor is before the catalytic converter, and downstream is after. The first one provides feedback for the ECU to control the fuel-air mixture. The second one is used only to check converter performance. On some models they are the same part type and on others they are different.

 

ok thank you. i have a O2 sensor bad and i have a new one but its up stream and the one that is bad is down stream. just didnt know if it would work