Modern vehicles are pretty complicated pieces of tech. Apart from emissions and other vital functions, the engine control system relies heavily on several sensors to regulate performance.

That is where oxygen sensors come in. They are a crucial element of your system and require proper maintenance to keep fuel consumption, driveability problems, and emissions at bay. 

In this article, we’ll talk about oxygen sensors. We will explain what they are, give all symptoms of a faulty sensor and explain when you should replace it.

Oxygen sensors, also known as O2 sensors, monitor how much unburned oxygen is left over after the exhaust exits the engine. They provide a means of measuring the fuel mixture and let the onboard computer know if the mix is burning rich (not enough oxygen) or lean (too much oxygen). This data allows your vehicle’s engine to make changes to ensure proper functioning. 

ODB-II regulations were strict enough, and businesses had to comply, and these sensors became mandatory on all cars in 1981. Some car models may even have as many as four installed. All vehicles made after 1996 are required to have an O2 sensor directly under the catalytic converter to tie all loose ends and prevent engine failures. 

The answer to this question is complex, as these sensors are not your standard maintenance items. No indicator lights on your dashboard or other means could hint at faultiness. 

But, alarmingly enough, they are one of the most crucial engine parts. As mentioned above, they monitor oxygen levels and feed the information to the onboard computer, which adjusts everything accordingly. Move the O2 sensor out of the picture, and your vehicle will not be able to set the air-fuel ratio, which brings down fuel economy, overheats the catalytic converter, and can cause a host of other issues.

However, the symptoms point to faultiness, which varies in nature but indicates a potential issue with the sensor.

Symptoms will help you tell if there’s something wrong with your O2 sensor. Most of the time, they will have to do with the engine and vary in noticeability.

One of the more evident signs is that your engine misfires or your vehicle runs roughly or irregularly during idle. Moreover, other performance issues are associated with a faulty O2 sensor, like stalling, hesitation, and loss of power. 

If you notice any of these and see that the check engine light is on, you can be sure that your sensor is acting up.

The Check Engine light illuminates for various reasons. First, you have to determine what the error code means. You can go to an auto shop and run diagnostics. If it's your O2 sensor, you should go to a mechanic and do your replacement there. 

If your sensor is genuinely at fault, the problem is easily fixed with repairs, which will set you back about $175. The final cost, though, will depend on your car model. 

A faulty oxygen sensor heavily brings down fuel combustion and delivery systems. If it does not operate properly, too much fuel will get into the engine, and you will notice significantly lower gas mileage than usual. Additionally, excess fuel in the engine may produce a sulfuric smell that will heavily remind you of rotten eggs. You may also notice black smoke emitting from the exhaust. 

Whenever the check engine light is on, and you experience any symptoms, you should immediately take the vehicle to an auto shop and replace your sensor. Generally, a new sensor will last anywhere from 60,000 to 90,000 miles. Drive safe and do your yearly maintenance!

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© 2022 J.D.Power. All rights reserved.

© 2019 J.D.Power. All rights reserved.