Oxygen sensor analyzer provides a way to identify faulty oxygen sensors in cars; thereby helping us to identify defective oxygen sensors. This article provides an overview about the use of oxygen sensor analyzer as a diagnostic tool to debug oxygen sensor issues in automobiles.

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.

A faulty O2 sensor starts with sudden decrease in vehicle’s gas mileage (the vehicle starts consuming more gas than usual). A defective sensor makes the air-fuel mixture to run too rich or too lean resulting in poor fuel economy. The defective oxygen sensor also shows up as a check engine light or malfunction indicator lamp illuminating in the vehicle’s dashboard. But this can happen due to many other reasons (defective oxygen sensor being one of them).

Perhaps the most accurate diagnosis of a defective oxygen sensor can be done using an OBDII code checker. OBD2 code readers have been widely used since the 1990s to diagnose defective oxygen sensors. 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 mixture and 0.9V for rich air to fuel mixture. So the new OBD2 equipments can test how fast or slow the oxygen sensor transitions between lean and rich mixture levels and hence determines the response time of the oxygen sensor with known "good" values.

Like the OBD2, oxygen sensor analyzer can also be used to identify these defective or lazy oxygen sensors as they are popularly called. Lazy because they may have a slower response time and might not set any codes on the OBD2 code reader; hence remaining undiagnosed. Oxygen sensor analyzer can identify these slow oxygen sensors; thus providing us with a more effective diagnosis capability. Many oxygen sensor analyzers available in the market can test the oxygen sensors in 8-10 secs, thus making them faster than those standard tests were we inject propane, after which we capture and analyze the transients on a DSO when the throttle is snapped.

Oxygen sensor analyzer is capable of displaying the sensor operations in real time, with no delay in a closed loop condition. These analyzers can indicate how efficiently these sensors are controlling the car engines. They can also be used to diagnose problems associated with dirty mass airflow sensor, bad fuel pump or filter etc. Oxygen sensor analyzers can also be used to identify if the air- fuel mixture in rich or lean; thus giving an insight into the proper functioning of the sensors. These analyzers can also perform tests recommended by the California Bureau of Automotive Repair. It’s a 100msec Snap Throttle Test, which requires the oxygen sensor to transition from below 0.175V to over 0.8V in less than 100msec when throttle snaps. Doing these tests using the analyzers doesn’t require propane making the test much simpler than when using a DSO. Many analyzers displays the results in a simple pass or fail mode. This test covers all failure modes of oxygen sensors, including contamination by coolant or silicon.

The analyzer probes are usually made of Teflon, which makes it capable to withstanding high temperatures. These analyzers are portable hand held units and are battery operated. They are capable of diagnosing 1 wire to 4 wire sensors.

Thus oxygen sensor analyzers provide an alternative way to identify and debug oxygen sensor issues and have proved to be a valuable and easy to use diagnostic tool.