I've heard that the O2 sensor was one of those fixes that is easily done and stupid to pay a mechanic $300 for. Bought the sensor, got the truck on jack stands take a look and the before cat sensor is facing down, easily accessible, and looks ridiculously simple. I take a look after the cat at the downflow sensor, there's a metal plate making it impossible to reach from the close side attached to the 2 bolts on the sensor so you HAVE to reach it over the top of the pipe making it impossible to fit any kind of wrench there. Not only that the wire trails up and INTO THE BOTTOM OF THE CHASSIS before the connector. There's a rubber gasket on the body that looks like it would need replacing if I rip it out and who know how far in the connector is. DAMMIT this pisses me off so much. From what I read the upflow sensor hardly EVER needs replacing. Anyone replace the after cat one on this truck before?
2000 Tacoma SR-5 4 cylinder 2.4L extended cab manual