Back to all

Why You Have an O2 Sensor (Oxygen Sensor)

May 14, 2023

If someone asked you what gas made up the largest portion of the atmosphere, what would you guess? Well, it's not oxygen; it only makes up 20.9 percent.  But since we're talking about oxygen, you should know that your vehicle uses oxygen sensors to make sure your engine is running the way it should.

The oxygen sensors measure how much oxygen is in your exhaust.  If there's too much, it means there's a problem with the mixture of fuel and air.  The sensor sends signals to computers in your engine and adjusts the mixture so it maximizes performance and efficiency.  It does this constantly. 

Many vehicles have multiple oxygen sensors.  Some have one close to the engine, another close to the muffler.  Two measurements are better than one since they allow readings to be more accurate.  You may have a vehicle with a dual exhaust, so you'd have twice as many oxygen sensors.

Your oxygen sensors can fail.  One thing that can damage them is contamination from bad fuel.  The sensors can simply wear out, though they usually last a long time.  It's not unusual for an oxygen sensor to last 100,000 miles/160,000 km. One more thing that can cause an oxygen sensor to fail is residue from an engine that's burning oil.  Plus contaminants from the road like salt can also cause problems. 

Here are some signs that your oxygen sensors might be failing.

  • The Check Engine light goes on.  In this case, your service facility can plug in a device that will read the code in your engine's computer to see if that's the problem.
  • The engine is running roughly.
  • Black, sooty smoke is coming out of your tailpipe.
  • Your fuel economy is noticeably lower than it used to be.

Head to your service facility and tell your advisor what symptoms your vehicle is experiencing.  They have the equipment and training to track down the issue.  Note that simply replacing the oxygen sensor is often not enough since it doesn't get to the root of the problem; other repairs may be needed. 

So make sure your oxygen sensors are working the way they should be.  Oh, and back to the question of what gas makes up most of the Earth's air?  It's nitrogen, which comprises 78 percent of the air we—and our engines—breathe.

Tuffy North Clermont
1315 E. Highway 50
Clermont, Florida 34711
(352) 241-9466
https://www.tuffynorthclermont.com/

More articles from Tuffy North Clermont Hwy 50

Light Up your Life (Headlamp Replacement)

June 9, 2025

Did you know that having a burned out headlight can result in your rearview mirror reflecting some flashing lights? In other words, you might get pulled over by the police for only having one working headlight, because in most places it's against the law. Not only is it illegal to drive with one... More

Combustion Choreography: Timing Belt Replacement at Tuffy North Clermont in Clermont

June 2, 2025

Have you ever seen a ballet performance? Have you wondered how all of those dancers manage to travel all over the stage jumping and twirling and never crash into each other? That's the job of a choreographer.Our auto engines are also highly choreographed. Pistons travel up and down inside cylinde... More

Making Sense of the O2 Sensor (Oxygen Sensor Replacement)

May 26, 2025

As you know, todays vehicles rely on a lot of computers in them to keep them running clean and efficiently. Those computers depend on information delivered by several sensors throughout the engine and exhaust system. And one of the most important is the oxygen sensor. Known as the O2 sensor f... More