Help! I'm at the end of my rope

[mustachio]

Firstly, I am not a very experienced car person. To tell you the truth I only recently started trying to do my own work and before this, it was going fine. My problem is that my check-engine light came on in my 2000 Corolla and when I took it up to O'Reillys to get it scanned, it said that my bank one oxygen sensor was bad. The O'Reillys guy said that was my upstream sensor so that's the one I bought. I thought(according to my Haynes manual) that my car had 2 sensors, one at the rear of the car and one under the center console(which I took to be the upstream one because it is closer to the engine). So I took off all the parts required to take remove my front console(ie..glove box, front trim, exc) pulled up my console and there was nothing there resembling the oxygen sensor I had bought. The manual made it seem like it was right there, but..nothing. I then looked at e-how made for changing the O2 sensor on a 1999 Corolla and it said that the O2 sensor was betweeen the cylinders and the radiator, sticking out perpendicular from the exhaust manifold. Once again they said it was obvious to see as it is a 3 inch tube sticking out. But once again my idiot brain couldn't find it. Can someone please help me on this? Is it underneath the front console or the hood and I'm just missing it or do I need to change the rear one? Or option C: I am a moron. Thank you in advance, wizards of mechanics.

[Corollaczy]

between the radiator and the block would be if the engine was facing the other way, which most 4cylinders are. But were you checking inside your car for the o2 sensor? Ive never changed one out but I know it should be somewhere between your header and your cat. I think its right as the 4 header tubes collect into the main pipe, between your engine block and the fire wall

[landphil]

The primary, (or upstream) o2 sensor in the manifold at the back of the engine (between the engine and the firewall) above where the exhaust pipe connects (that's under the hood.) and held in by two 8mm studs - the nuts take a 12mm socket/wrench. The secondary O2 sensor is in the exhaust pipe behind the catalytic convertor.

[mustachio]

Originally Posted by landphil

The primary, (or upstream) o2 sensor in the manifold at the back of the engine (between the engine and the firewall) above where the exhaust pipe connects (that's under the hood.) and held in by two 8mm studs - the nuts take a 12mm socket/wrench. The secondary O2 sensor is in the exhaust pipe behind the catalytic convertor.

Thank you so much. I found it and am changing it now.