Well, it's not under the seat. You car has four sensors. It's best to replace all four at once, if one is dying or dead, the others aren't far behind. The sensors are bolted into the exhaust pipes on the car. When you order them, make sure you get TWO for BEFORE the converter and TWO for AFTER the converter. Then, it's just a matter of crawling under there and using a (I think) 15/16" wrench. They make a special socket that has a slot in it to accomedate the wires coming from the sensor, but I found I didn't need one for my 99 Rodeo.
You might find it easier to get the sensors out if you let the engine warm the exhaust a little. After you install the new sensors, pull the ECM fuse in the fuse box under the hood to reset the computer. Drive and be happy!
Monday, February 27th, 2017 AT 4:57 PM