check engine light

2007 Toyota Tacoma, 4cyl, stick shift........check engine light has been coming on and off for about the last 6 months. It will come on , stay on a week or so and then go out without me doing anything. Light came on again about 3 weeks ago and stays on. Took it to Auto Zone, they told me it was Code P0031, heated Oxygen sensor, heater, low circuit , bank 1 , sensor 1..........He told me this is easy to change, however, I don't know exactly where it is. Does anyone have a diagram or tell me where on the internet I might find a diagram? I could change it if I knew where it was. Any help is greatly appreciated

 

You only have one "bank" with a 4 cylinder. If you look at the exhaust manifold, sensor 1 is close to where the exhaust pipe leaves the engine. Sensor 2 is always downstream of the cat so it is on the back side of the cat looking from the driver's side... If you find the one behind the cat, work forward and it will be the only other one you see.

 

Excellent first post! Welcome to TW.

 

Follow up.............Changed the upstream sensor and light is out. Relatively easy job,,soaked the old sensor with lubricating oil and let sit overnight and old sensor came out easy, didn't need a cheater. Found part online for $105......exact same Denso part local parts store selling for $175. Again, thanks for your help, much appreciated