Scanned my truck and it looks like bank 2 sensor 1 is bad. Thats the passenger side sensor upstream of the cat. right?? I need to order the part and I don't know what part to get? Is it a 3 or 4 wire? And what is the part #? I'm just going to buy a cheap one (under $40)

 

Keep in mind that DTC's never tell you that a part is bad. It tells you what circuit malfunctioned, and you need to follow the diagnostic flow chart to pinpoint the problem. Post the DTC and we can give you a link to the proper flow chart.

You are correct, B2S1 is the sensor closest to the exhaust manifold, passenger, (right) side. Year, make, model & engine is necessary to determine the part number.