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 )
there are 4 o2 sensors
There are 2 oxygen sensors.
A 2001 Ford Explorer Sport , with the 4.0 liter Single Over Head Cam V6 engine should have ( 4 oxygen sensors )
how many o2 sensors on a ford e350 van 2003
( two ) I believe they are in the outlets of the two exhaust manifolds
The O2 sensor on any vechicle will be located on the exhaust manifold.
i wanna say four two before the cat and two after it.
4 ======================================================= The above answer is correct if you have the 5.0 liter V8 engine in your 1996 Ford Explorer , but if you have the 4.0 liter EFI , V6 engine ( VIN " X " ) there are ( 3 oxygen sensors )
If it's like a 1991 Ford Explorer ( with the 4.0 liter V6 engine ) It has ( 1 ) oxygen sensor
two oxygen sensors for air / fuel ratio (and another two oxygen sensors that are called catalyst monitors installed downstream )
The 1992 Ford Taurus has two oxygen (O2) sensors. Both O2 sensors are located upstream of the catalytic converter with one on each exhaust bank.
I can assure you that the O2 sensors will not prevent the enigne from starting, even if they are disconnected or removed. Something else is the culprit.