The oxygen sensor or O2 sensor as it is commonly called plays an important role in monitoring the oxygen content of the car's exhaust system. It determines the optimal mixture of air to fuel ratio needed to run the vehicle. A defective sensor can greatly affect your vehicle's fuel consumption because it allows the vehicle to use more fuel than what it should. Hence faulty sensors need to be diagnosed and replaced promptly.
But determining if the O2 sensor is really defective will need accurate diagnosis. Equipments like the OBD2 code reader can be used for this purpose. OBD stands for On Board Diagnostics. OBD2 is a diagnostic system, which monitors the performance of vehicles by performing tests associated with its specific systems or components. The 1990 Clean Air Act (CAA) made it mandatory for all vehicles sold in USA to have some form of diagnostic system. Hence all light duty vehicles from 1996 onwards were manufactured with OBD feature.
The emission testing done by OBDII is more comprehensive than the tailpipe test because unlike the traditional tailpipe test, which provides the emission results of only a specific moment (only during testing), the OBD2 code reader can monitor the vehicle emission at various moments when the vehicle is in operation.
The first generation of OBD, called as OBDI provided a simplistic test to determine the health of the oxygen sensor. Oxygen sensor testing using OBD1 involved determining if the sensor was stuck lean or rich for 30 seconds or more. The OBDI systems didn't have any way to determine the response time of the oxygen sensors.
Oxygen sensor testing using OBD2 does look at the response time as well. A good upstream oxygen sensor produces an oscillating waveform that toggles between 0.1V to 0.9V. The sensor indicates 0.1V for lean http://www.ecomed.co.za/99-portable-oxygen-concentrators
