Shouldn't the two oxygen/O2 sensors be the same part? Why does Majestic Honda show two different part numbers for the two sensors on a 99 Civic DX-V?

Select EXHAUST MANIFOLD(1) from the System/Component list and the O2 sensors are part 8 and 9: http://*******.com/paqegt

 

its becase they are not the same part.
they both moniter different things.

 

The sensors themselves ("4 wire heated oxygen sensors") are exactly the same. The part numbers are different because one might have longer wires, one might have a female plug instead of a male plug, one might have a rubber grommet on it to mount under the car, one might have a rubber sleave on it to mought to some bracket...etc. Capiche!?!?!