After you remove the air filter housing you should be able to access the wiring connection to both the left and right sensors. I think it's a 4 pin connector. You could measure resistance and see if it's over 5000 Ohms for either side to see which one is bad.
Once you have the air filter housing off, it's pretty easy to replace the sensor. It might make sense to just buy a right and left one and replace both at the same time. I'd buy the cheaper Bosch sensor because it looks identical to the factory part and suspect that is what the factory part is.
