Located in front of the tailpipe, the oxygen (O2) sensor keeps track of the oxygen levels in your vehicle’s exhaust. This information is important because the engine control unit (ECU), your automobile’s main computer chip, uses it to keep the air and fuel balanced in the combustion chamber. Trinity Automotive advises that your oxygen sensor can start to malfunction at around 90,000 miles. Some sensors last longer than this, but when this happens, you will notice the following signs of a faulty O2 sensor.
1. Acceleration/Engine Performance Issues
Once the O2 sensor goes bad, it skews the data sent to the ECU. Consequently, you end up with an imbalance of air and fuel in the combustion chamber. When this happens, you may notice that your acceleration lags, and your engine stutters at higher speeds. This is an indication that there is more air than fuel in the chamber. If there is more fuel than air, your engine will buck like a bronco.
2. Black Exhaust Flowing Out of the Tailpipe
Another sign that the ECU has put too much fuel in the combustion chamber is black exhaust flowing out of your vehicle’s tailpipe. This happens because the engine ignites the excess fuel and burns it away. The exhaust is a result of this burn. Unfortunately, you will continue to have exhaust problems until you replace the malfunctioning O2 sensor.
3. Check Engine Dashboard Warning
Oftentimes, when the O2 sensor goes bad, it will send an error code to the ECU. This triggers the ECU to turn on your vehicle’s check engine light. There is no other light that covers the O2 sensor, so the check engine light will illuminate on the dashboard when the O2 sensor is faulty and needs to be replaced.
4. High Emissions Levels, Especially Carbon
A malfunctioning oxygen sensor can also cause an increase in your vehicle’s emission levels, especially the carbon levels. This happens when the combustion chamber is burning away too much fuel. The excess fuel burn increases the levels of carbon found in your vehicle’s exhaust.
5. Rotten Egg Smell in the Exhaust/Engine Bay
This excess fuel burn can also damage the catalytic converter. When this happens, you may smell rotten eggs in your automobile’s exhaust and/or coming from the engine bay. A malfunctioning catalytic converter can also cause your vehicle’s engine to overheat.
6. Unexplained Loss of Fuel Economy
Finally, you might be able to blame your sudden loss of fuel economy on the faulty O2 sensor. Again, if this sensor skews the data that is sent to the ECU, you will end up with an incorrect mixture of air and fuel in the combustion chamber. This directly affects your fuel economy.