It resembles a spark plug with wires attached.
the o2 sensor is in the exaust manifold or down pipe it looks like a sparkplug with wires
Look on exhaust manifold.
An O2 sensor unscrews just like a spark plug.
The sensor between the cat and the engine is the air fuel ratio sensor, it looks like an o2 sensor. The o2 sensor is between the cat and the tail pipe. The forward sensor is the af sensor t he rear one is the o2 sensor. Thar answer is for the calif. vehicles. Fed may be different but I dont think the 4 runner had two o2s like some of the sedans. fairly visable tho.
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In the exaust manifold. If you raise the hood and look down on the front of the engine, you will see the exaust manifold, and there will be a sensor screwed into the middle of that manifold. That is the O2 sensor. There is another sensor further down the exaust system that looks just like it that some people mistake for an O2 sensor, but that sensor is called a catalyst moniter. But the one you can see while standing in front of the car with the hood up is the O2 sensor.
It depends on which sensor, O2/camshaft,etc. The O2 sensor is a straight metal sensor that is screwed into the exhaust. There is an upstream/bank1-sensor1 or down stream/bank1-sensor2 after the catalytic converter. A camshaft sensor is an L shaped, usually black sensor that is installed into the head closest to the firewall(bank1).
Depends on what the problem is or what code was set.
between the radiator and the front of engine there are 2 of them they look like spark plugs and have cables attached to them
No activity from B1 S2 O2 sensor circuit. Check O2 harness and connecter for damage. If harness and connecter look good replace faulty B1 S2 O2 sensor. This is the sensor after the B1 catalytic converter (AKA downstream O2 sensor). B1 (Bank 1) is the bank of cylinders that contains the number one cylinder.
O2 sensor CKT slow response (bank 1 sensor 1). Sounds like a tired B1S1 O2 sensor if all the connections are good.
There is most likely 2 or 3 O2 sensor's on your car. Just follow the exhaust system starting from the motor you should see them.