o2 sensors are in the exhaust Usually in front of the catalytic converter near or in the exhaust manifold.
The are two o2 sensors in an 04 Sentra. One is called the front sensor, and it is in the engine compartment, in the exhaust manifold. The other, the rear one, is in the exhaust pipe under the car, past the catalytic converter.
Gas mileage also went down and I just replaced o2 sensors.
There is a total of 3 O2 sensors 2 Upstream and 1 Downstram
one
four
check your exhaust system there should be a wire running in to your exhaust tat is your o2 sensor good luck There are two o2 sensors, one in the engine and one coming out of the Cat Converter in the exhaust system.
there are 4 sensors 2 in the front and 2 in the back
Assuming you have the V-6 engine, it has two downstream (after the cats) O2 sensors and two upstream (before the cats) Air/Fuel Ratio Sensors. So the answer to your question is two O2 sensors.
Replace the Downstream O2 sensor (after the catalytic converter)
All O2 sensors are threaded into the exhaust system at various points.
There are four o2 sensors on a montero sport.