Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
That would be the sensor itself. However, you will want to check that the wires and connectors are all good. There is always a chance that the PCM has an internal problem but whenever I have run into this, it was the sensor. Here is some of the tests for it along with a wiring diagram. The tests came out in reverse on the paste. You would start at one, (of course)