April 2021

T An oxygen sensor’s life expectancy can vary greatly depending on the condition of the vehicle and whether it is properly maintained. Generally, based on typical maintenance routines, an oxygen sensor’s effective life span is between 30,000 and 50,000 miles. After that, performance begins to degrade, which will in turn affect the vehicle’s overall fuel economy and performance. That can arrive quickly in the eyes of today’s drivers, many of whom won’t have their vehicle paid off by the time it needs to be replaced. However, if the engine is properly maintained in all aspects, the oxygen sensors could last much longer, up to 100,000 miles in some cases. The truth is, many vehicles on the road today would not meet the maintenance requirements to achieve that level of sensor life. It’s no surprise that oxygen sensors need to be checked regularly and replaced as needed. They per¬form under fierce conditions, battling harmful exhaust gases, extreme heat and high velocity particulates. And the harder someone drives his or her vehicle, the more punishment the sensors take. The oxygen sensor’s impact It is a key component, as faulty oxygen sensors cause a very large amount of emission inspection failures. Why? Because not all oxygen sensors are created equal. The oxygen sensor reports to the engine management computer the air/fuel ratio in the exhaust system. While it no longer is a one-wire unheated sensor like it was in the 1970s, but rather a four-wire or five-wire air/fuel ratio sensor, that means it can report information more accurately, but can be damaged more easily. These sensors include heated, fast light off, ultra-fast light off, Titania, zirconia, thimble, planar and wideband sensors. Staying up- to-date with these technologies is critical in diagnosing the oxygen sensor and this technology will only continue to grow as emission controls become stricter every year. Two scenarios What goes wrong? A few things, actually. There are two scenarios technicians need to look for when inspecting an oxygen sensor to determine the cause of failure, and thus find the root cause of the problem. First, it can happen instantaneously when a contaminant comes into contact with the oxygen sensor’s ceramic element. Technicians who suspect this type of failure should look for evidence of certain types of silicone compounds or of an engine that is burning oil. Small amounts of tetraethyl lead in gasoline as well as over-the-counter fuel additives that are not 26 AFTERMARKET APRIL 2021 TECHNICAL www.aftermarketonline.net EXPLAINING THE OXYGEN SENSOR The Walker Product Development Team discuss the importance of the oxygen sensor in the efficient running of an engine Above: Oxygen sensor cutaway