That Vehicle has 2 oxygen sensors.
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I'm not a mechanic / technician but on a 1988 Ford Ranger there might be ( 1 ) oxygen sensor ( upstream sensor )
My 1995 Ford Explorer with the 4.0 L OHV engine has 2 , so I'm assuming your 1995 Ford Ranger 3.0 L would also have 2
On a 1995 Ford Explorer : There are ( 2 ) oxygen sensors ( I believe there is one sensor in the outlet of each exhaust manifold )
There are 2 heated exhaust gas oxygen sensors , 1 screwed into the outlet on each exhaust manifold on a 1993 Ford Ranger 4.0 L .
According to the engine wiring schematic in my Chilton book : For a 1999 Ford Ranger , 4.0 liter EFI , V6 engine : ( there are 3 oxygen sensors )
I was looking in my Chilton book at the engine wiring schematic for a 1993 Ford Ranger 2.3 liter 4 cylinder and I only see ( 1 ) heated oxygen sensor
there should be 3/1 on the left header then 2 going back
That would depend on what year of Ford Explorer and which engine you have ( my 1995 Ford Explorer with the 4.0 liter OHV , V6 engine has ( 2 oxygen sensors )
A little more information please ( what year of Ford Ranger , what size is the engine ) As far as I know there could be as many as four oxygen sensors or as little as one depending on the year and engine size
where are the oxygen sensors on a 2004 ford escape with a 3.0 engine