How many 02 sensors on 1999 ford ranger xlt 4.0?

Answer 1

( 3 ) O2 sensors , according to the engine wiring schematic in my Chilton book

( 2 ) would be before the catalytic converter ( upstream ) and ( 1 ) after the

catalytic converter ( downstream ) The ( 2 ) upstream sensors would be used

to determine the air / fuel ratio for the engine and the ( 1 ) sensor after the

catalytic converter is called a catalyst monitor