Where is the oxygen sensor on a 1991 ford explorer?

Answer 1

The Oxygen Sensor on a 1991 Ford 4L, 4 door, 4 WHD, Explorer is only visible from beneath the vehicle. There is only one sensor.From under the vehicle look for the point at which the left and right headers join together into a single pipe.

Follow the single pipe a foot or so and just before it joins the Catalytic Converter you will see what looks somewhat like a spark-plug sticking vertically out of the single pipe. That's the Oxygen Sensor.

There is a bolt like fitting on its bottom which you can get a wrench on to remove it.

The device has a wire coming out of its top which disappears upwards and connects to a wiring harness up behind the back of the engine. One can buy a notched aftermarket socket designed to avoid this wire during removal.

The 1991 Explorers come with either a 3 or 4 wire Heated Oxygen Sensor. You need to have yours removed from the vehicle to be sure which type you have. They are not interchangeable.