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When a car’s being driven, it produces waste gases that need to be carried away from the engine. The exhaust system in a vehicle plays a crucial role in managing emissions and expelling fumes. The oxygen sensor, also known as an O2 sensor, is a key component of the exhaust system that measures the amount of unburned oxygen in the exhaust.
What does the O2 sensor do? The O2 sensor communicates with the vehicle's electronic control unit (ECU) to determine the optimal air-to-fuel ratio for engine performance. O2 sensors became mandatory in vehicles in 1981, and many vehicles made after 1996 have multiple oxygen sensors to monitor the catalytic converter.
These components work together to communicate with the fuel injection system to help maintain the performance of the vehicle. Signs of a failing O2 sensor include decreased gas mileage, engine misfiring, drop in engine power and a rotten egg smell. It is important to have a trained technician diagnose and fix the issue.
Keep reading to find out more about how the O2 sensor works within the exhaust system and why it’s so important.
Where Is the O2 Sensor Located?
The oxygen sensor in a car can be found within the exhaust manifold, which is connected to the engine and helps collect emissions. The manifold receives a mixture of air and fuel from engine cylinders.
Warning Signs of a Failing O2 Sensor
O2 sensors don’t require regular maintenance like air filters or oil filters, but over time they can start to wear out. A failing oxygen sensor could lead to the ECU being unable to regulate the proper air-to-fuel ratio, which can cause engine performance issues.
Here are some possible indicators of O2 sensor wear and tear:
- Decreased gas mileage: A failing oxygen sensor could cause an increased amount of fuel injected into the engine, resulting in significantly lowered fuel economy.
- Engine misfiring: Rough idling and engine misfiring are common signs that an O2 sensor is failing. Combined with the check engine light, this can indicate that you need to have the part checked.
- Drop in engine power: An air/fuel mixture that isn’t regulated properly can cause performance issues, including difficulty accelerating or reaching full power. This can be the result of a worn O2 sensor.
- Rotten egg smell: Excess fuel in the engine can produce the smell of rotten eggs that comes from sulfur. Excess fuel could be due to a failing O2 sensor.
If you notice these symptoms or that your check engine light has come on, it’s important to take your vehicle to get looked at by a trained technician who can determine the source of the problem.
O2 Sensor FAQs
How does an O2 sensor work?
The O2 sensor in a vehicle measures the amount of unburned oxygen in the exhaust with the help of the vehicle's electronic control unit, which adjusts the how much fuel needs to go to the combustion chamber.
Why is an O2 sensor important in a car?
O2 sensors are mandatory in vehicles for a reason. Without an O2 sensor in your car, not enough oxygen or fuel will get in the exhaust, which can lead to car troubles.
What are the symptoms of a faulty O2 sensor?
Some symptoms of a faulty O2 sensor include:
- Check engine light turns on
- A rotten smell, or smoke
- Loud noises from your engine
- A dip in fuel efficiency
Get Trained on Exhaust Systems at UTI
You can get hands-on training for the automotive industry when you enroll in UTI’s Automotive Technology program.1,18 Through our combination of interactive labs and lectures, you could learn the fundamentals to become an automotive technician.
Courses you take during the program can help teach you to repair and maintain a range of vehicle systems, including the exhaust system and the O2 sensor. These skills can help you when applying for entry-level jobs in the industry.
Total auto technician employment is expected to exceed 815,000 by 2033.47 Take advantage of the opportunities and take the first step by requesting more information.
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1 ) UTI is an educational institution and cannot guarantee employment or salary.
2 ) For program outcome information and other disclosures, visit www.uti.edu/disclosures.
18 ) UTI now offers all of its automotive, diesel, motorcycle and marine technician training in a blended-learning format consisting of online lecture courses along with in-person, hands-on lab training.
47 ) The U.S. Bureau of Labor Statistics projects that total national employment for Automotive Service Technicians and Mechanics will be 815,900 by 2033. See Table 1.2 Occupational projections, 2023–33, and worker characteristics, 2023, U.S. Bureau of Labor Statistics, www.bls.gov, viewed November 4, 2024. UTI is an educational institution and cannot guarantee employment or salary.
Universal Technical Institute of Illinois, Inc. is approved by the Division of Private Business and Vocational Schools of the Illinois Board of Higher Education.
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