How Many o-2 sensors on '91 Ranger 3.0..?

[snahman]

Hello..Heard different that there's two. Is it heated or non heated..?.. I haven't been able to get under truck ( arthritis now....Where's it located..?.Thanks..!

 

[RonD]

1994 and earlier Rangers used only Upstream O2 sensors, no O2 sensor after the Catalytic converter(Downstream), that started in 1995 model year

Pre-1995
4cyl engines just had 1 upstream O2 sensor
V6 engines usually had 2 upstream sensors, one on each down pipe from each exhaust manifold before they "Y"ed together

But some older V6 engines did have just 1 O2 on the "Y" pipe

1991 3.0l should have 2
You can usually see them from engine bay, and unplug them also, but access to remove them is usually from under the truck
O2 sensors are all the same there is no left or right(or upstream/downstream), but.............they all come with leads and connectors attached and the length of the lead may be different from left to right, depends on the vehicle wiring harness of that year.
The connectors are also all the same so DO NOT mix up left and right plugins, do one O2 sensor at a time and plug it back in to correct wiring harness plug

All were Heated
4 wires at O2 = Heated O2 sensor

 

[snahman]

1994 and earlier Rangers used only Upstream O2 sensors, no O2 sensor after the Catalytic converter(Downstream), that started in 1995 model year

Pre-1995
4cyl engines just had 1 upstream O2 sensor
V6 engines usually had 2 upstream sensors, one on each down pipe from each exhaust manifold before they "Y"ed together

But some older V6 engines did have just 1 O2 on the "Y" pipe

1991 3.0l should have 2
You can usually see them from engine bay, and unplug them also, but access to remove them is usually from under the truck
O2 sensors are all the same there is no left or right(or upstream/downstream), but.............they all come with leads and connectors attached and the length of the lead may be different from left to right, depends on the vehicle wiring harness of that year.
The connectors are also all the same so DO NOT mix up left and right plugins, do one O2 sensor at a time and plug it back in to correct wiring harness plug

All were Heated
4 wires at O2 = Heated O2 sensor

Ok, thanks for that..Wonder why the aftermarket sells them that says it fit with only 2 wires and non heated....?