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How Can I Tell if My Car’s O2 Sensor Is Failing or Malfunctioning

The oxygen (O2) sensor is an important part of your vehicle’s exhaust system. This sensor is located at the beginning of your tailpipe. The O2 sensor tracks how much oxygen there is in your engine’s exhaust. It sends this information to the engine control module (ECM). If it sends the wrong information because it is malfunctioning, the ECM may make unnecessary changes in the combustion chamber. Techway Automotive lists the results of these unnecessary changes below. This is how you can tell that your oxygen sensor is failing or malfunctioning.

Black Exhaust Smoke

Assume for the moment that the ECM adjusted the amount of fuel in the combustion chamber and now it has too much. It made this adjustment based on incorrect readings from the oxygen sensor. Your engine will burn away the excess fuel and you will see black exhaust pouring out of your tailpipe.

Check Engine Light

Usually, the oxygen sensor will send an error code to the ECM if it is malfunctioning. This error code will cause the ECM to turn on the check engine light on your vehicle’s dashboard. Any time the check engine light comes on, there is something wrong with your engine.

Engine Performance Issues

If, as discussed in the above example, you have too much fuel in the combustion chamber, you will notice that your engine surges. This surging can be very disconcerting because your engine will pick up speed even though you didn’t press down harder on the accelerator.

Another example is the ECM puts too much air into the combustion chamber based on the oxygen sensor’s incorrect readings. In this case, your engine will struggle to run and accelerate because it has more air than gasoline in the combustion chamber.

Fuel Efficiency Loss

You will also notice that your fuel economy isn’t what it used to be if the O2 sensor is going bad. This is because of the imbalance of air and fuel in the combustion chamber. Your automobile will either burn away the excess fuel or use too much fuel because it’s struggling to run.

High Emissions Levels

If your vehicle is burning away excess fuel, this will directly affect the emission levels in your vehicle’s exhaust. Higher carbon levels will not only cause your check engine light to come on but also cause your vehicle to fail an emissions test.

Rotten Egg Smell

Finally, excess fuel conditions can put undue stress on your vehicle’s catalytic converter. The converter will clog and malfunction. When this happens, you will smell rotten eggs in your engine bay or in your vehicle’s exhaust. This smell is burning sulfur.

Techway Automotive is in Dothan, AL. You’ll also find a Techway Automotive shop in Blakely, GA. Call the shop that is nearest to you to schedule an appointment for an O2 sensor check.

Photo by Birdlkportfolio from Getty Images via Canva Pro
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