Oxygen sensor failure is one of the top 5 reasons your vehicle's CEL (check engine light) might come on. As a matter of fact, the most common car repair in 2015 was oxygen sensor replacement, making up 7 percent of all repairs in 2015. At Viper Motorsports in Weatherford, TX, we perform several oxygen sensor replacements and are often asked "what the heck is an oxygen sensor and what does it do?" So, here are the answers to those questions.
An oxygen sensor, also referred to as an O2 sensor or Lambda Sensor, is an electronic device, located in the exhaust system of most cars and trucks manufactured after 1980. It is used to measure the comparative amount of oxygen in a liquid or gas. In other words, the oxygen sensor performs constant tests, in real time, on your vehicle’s exhaust gases to determine how much oxygen is in it. There is a apparatus in most oxygen sensors that involves a chemical reaction that generates a voltage. the O2 sensor “sniffs” the exhaust, and depending on the air/fuel ratio levels, converts that reading into a voltage signal that is then fed to the engine's ECU (Engine Control Unit) which in turn, adjusts the amount of fuel entering the engine accordingly to obtain the most efficient engine performance.
The main reason internal combustion engines require oxygen sensors is that there are several variables that directly influence the amount of oxygen that the engine can pull, such as altitude, outside temperature, engine temperature, barometric pressure as well as the load on the engine at any given time
Additionally, the oxygen sensor keeps your emissions in check and can alert you when your vehicle's emissions are excessive. Many states (including Texas) require annual vehicle inspections to help regulate vehicle emissions. On 1996 and newer model year vehicles, this test utilizes the OBDII (On Board Diagnostics-Second Generation) system which is a computerized system that monitors emissions-related components and systems for proper functionality. State Inspectors use a scan tool that plugs into the vehicle's computer and downloads stored information from the vehicle's computer to identify emission systems or components that are not working properly. Therefore, if one or more of your vehicle's oxygen sensors is faulty during the annual State Inspection, you will most likely fail the inspection.
The O2 sensors are located underneath the hood as well as underneath the vehicle. They are screwed into the exhaust pipe, either in front of and/or behind the catalytic converter. The front (upstream) sensors measure the amount of oxygen in the exhaust gases as they leave the combustion chamber. The rear (downstream) sensors are located behind the catalytic converter and monitor the oxygen content of the exhaust gases leaving the catalytic convertor.
Traditional V6 and V8 engine vehicles typically have three oxygen sensors: a left bank and right bank upstream sensor as well as a downstream O2 sensor. 4 cylinder transverse engines usually have two O2 sensors: one upstream and one downstream. V6 and V8 transverse engines typically have four oxygen sensors including one left or front bank upstream sensor; a right or rear bank upstream sensor; a rear of engine sensor; and a downstream sensor. 4 and 6 cylinder in-line motors have three oxygen sensors including a front and rear bank upstream, and a downstream sensor.
With each new model year, vehicle manufacturers seem to be adding more oxygen sensors in an effort to meet EPA standards by better managing engine operation. There are some high performance engines that actually have O2 sensor for each cylinder as well as one for the rear of each catalytic convertor.
The first and most noticeable symptom that your oxygen sensor may be failing or has failed is the CEL. Although the CEL can light up for a number of reasons, in vehicles with high mileage, there is a good chance it is because of a bad O2 sensor. Running an engine diagnostic will determine the cause of the CEL. You may also notice that your car or truck has suddenly started getting very poor gas mileage. A bad oxygen sensor will result in an air to fuel mixture that is either too lean or too rich which will typically result in excessive consumption of fuel. A bad oxygen sensor can also slow down or even advance engine ignition timing which can cause the engine to ping or knock. Engine pinging and knocking usually occurs when the combustion gases are ignited at the wrong times. Lastly, you may experience other symptoms like: rough engine idle, engine misfire, or an engine that stumbles or hesitates when attempting to accelerate. Faulty sensor(s) can cause damage to your spark plugs and catalytic converter and can shorten their lifespan.
If you have been experiencing any of these problems, see the Exhaust experts at Viper Motorsports in Weatherford, TX. We will inspect your entire exhaust system including oxygen sensors for FREE. If they need to be replaced, we will have you back on the road quickly and at a price that won't break the bank. Call us at (817) 609-8001 or visit us at 905 Fort Worth Hwy., Weatherford, TX. www.vipermotorsports.com
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