An oxygen (O2) sensor is a key components in the vehicle's pollution control system. The front oxygen sensor produces a signal that the fuel injection computer reads and determines if the engine needs more or less fuel in order to optimize fuel consumption while the rear oxygen sensor monitors the efficiency of the catalytic converter. Over time oxygen sensors' output signal deteriorates and an oxygen sensor replacement becomes necessary.
When performing an oxygen sensor replacement, the negative cable is removed form the battery and the sensor's electrical connections are removed. Then the sensor is removed form the exhaust pipe or exhaust manifold and the new sensor is installed.