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Your vehicle’s oxygen (O2) sensor may be small, but it plays a big role in keeping your engine running efficiently. Located in the exhaust system, the oxygen sensor measures the amount of oxygen in the exhaust gases and sends that information to the engine control module (ECM). The ECM uses this data to adjust the air-fuel mixture for optimal performance, fuel efficiency, and emissions control.
When the oxygen sensor begins to fail, it can cause a range of issues that impact your vehicle’s drivability, fuel economy, and emissions. Knowing the warning signs can help you catch the issue early and avoid costly repairs.
Check Engine Light Illumination
One of the most common indicators of a bad oxygen sensor is the check engine light. Because the oxygen sensor is vital to the engine’s fuel management system, the ECM will detect when it is not providing accurate readings and trigger the warning light.
While the check engine light can come on for many reasons, a diagnostic scan can determine whether the oxygen sensor is the culprit. Ignoring this light can lead to more serious problems, as the engine may run too rich or too lean without proper sensor input.
Poor Fuel Economy
A faulty oxygen sensor can disrupt the delicate air-fuel balance in your engine. If the ECM receives incorrect data, it may instruct the engine to use more fuel than necessary, resulting in a noticeable decrease in fuel economy.
If you find yourself filling up more often without a change in driving habits, the oxygen sensor could be to blame. Restoring proper sensor function can often bring fuel mileage back to normal levels.
Rough Engine Performance
When an oxygen sensor is failing, the engine may not receive the correct fuel mixture, leading to rough idling, hesitation during acceleration, or even stalling. You might also notice a loss of power, particularly when trying to accelerate or climb hills.
These performance issues can make driving less enjoyable and, in some cases, unsafe. Prompt repair can help restore smooth, reliable operation.
Increased Emissions
A faulty oxygen sensor can cause the engine to burn fuel inefficiently, resulting in higher emissions. This may not be obvious in everyday driving, but it can cause your vehicle to fail an emissions test.
Because the oxygen sensor plays a direct role in controlling emissions, replacing a faulty one is often necessary to meet environmental standards and maintain compliance with local regulations.
Strong Fuel Smell from the Exhaust
If the engine is running too rich due to a bad sensor, you may smell unburned fuel coming from the exhaust. This indicates that fuel is not being burned completely in the combustion chamber, resulting in wasted gas and increased emissions.
While a fuel smell can result from other issues, such as leaking injectors or a bad fuel pressure regulator, it is worth having the oxygen sensor checked as part of the diagnosis.
Why Oxygen Sensors Fail
Oxygen sensors are exposed to extreme heat and constant exhaust flow, which means they eventually wear out. Contaminants from fuel additives, oil leaks, or coolant leaks can coat the sensor’s tip and reduce its accuracy. Over time, this buildup prevents the sensor from responding quickly to changes in the air-fuel mixture.
Most oxygen sensors last between 60,000 and 100,000 miles, depending on driving conditions and the specific type of sensor.
Replacing a Faulty Oxygen Sensor
Replacing a bad oxygen sensor is generally straightforward, but the process requires the correct tools and knowledge to ensure the sensor is installed properly. Using the correct OEM-quality sensor for your vehicle is important to maintain accurate readings and proper performance.
After replacement, the ECM may need to be reset or relearn its fuel trims, which is another reason professional installation is recommended.
Preventing Future Issues
Regular maintenance, such as addressing oil or coolant leaks promptly and using high-quality fuel, can help extend the life of your oxygen sensors. Keeping up with manufacturer-recommended replacement intervals also reduces the risk of poor performance and high emissions.
If your check engine light comes on or you notice symptoms such as reduced fuel economy or rough performance, do not delay in having the system checked.
Oxygen Sensor Service at Valley Automotive in Covington, WA
A failing oxygen sensor can affect everything from fuel efficiency to engine performance and emissions. At Valley Automotive in Covington, WA, we can diagnose sensor issues, replace faulty components with quality parts, and ensure your engine runs efficiently and cleanly.
Schedule your oxygen sensor service today and keep your vehicle performing at its best.