Depending on the engine it will have between 4 and 2.
If you had a straight 4 or 6 engine then there would be only 2, one on the exhaust manifold or exhaust pipe and then one just after the catalytic converter.
If you have a "V" engine (V8, V6) then you have an oxygen sensor on each exhaust manifold and will have a catalytic converter for each bank of the V. There will also be an oxygen sensor downstream of each converter as well. In this case there would be 4 oxygen sensors.
There will be
If you had a straight 4 or 6 engine then there would be only 2, one on the exhaust manifold or exhaust pipe and then one just after the catalytic converter.
If you have a "V" engine (V8, V6) then you have an oxygen sensor on each exhaust manifold and will have a catalytic converter for each bank of the V. There will also be an oxygen sensor downstream of each converter as well. In this case there would be 4 oxygen sensors.
There will be