7 Clear Signs That an Oxygen Sensor Is Starting to Fail

Oxygen sensors play a vital role in maintaining your Subaru’s performance. These sensors help your vehicle’s computer (ECU) monitor and adjust the air-to-fuel (AFR) ratio. This is important because the ideal AFR ratio is 14.7:1. This means that for every 14.7 parts of air, there should be one part of fuel. 

When the AFR ratio is too rich or too lean, it can decrease performance and fuel economy. Additionally, an incorrect air-to-fuel ratio can cause your engine to run hotter than normal, which can lead to engine damage. 

If your vehicle is starting to experience any of the following issues, it may be a sign that the oxygen sensor is starting to fail:

1. Poor Fuel Economy

Poor fuel economy is one of the first signs that an oxygen sensor may be starting to fail. As your oxygen sensor fails, it will become less accurate in monitoring the AFR. This can lead to your engine running leaner or richer than usual, impacting your fuel economy.

You may notice that you are filling up your tank more frequently or that your vehicle is no longer getting the same number of miles per gallon. 

2. Decreased Performance

If your oxygen sensor is not functioning properly, it can cause your engine to run leaner or richer than normal. This can lead to decreased performance, as your engine will not be able to produce as much power.

You may notice that your vehicle is slower to accelerate or that it is lacking in power when climbing hills.

3. Engine Light On

Another common symptom of a failing oxygen sensor is the engine light coming on. This is because the sensor is not sending the correct signal to the engine control unit.

And when it is not functioning properly, it can cause your vehicle to emit higher levels of pollutants. Eventually, this causes the engine to run leaner than it should. 

4. Engine Misfires 

If your oxygen sensor is not functioning correctly, it can cause your engine to misfire. This is because the sensor is not sending the correct signal to the ignition system, causing the spark plugs to fire at the wrong time.

You may notice that your vehicle is shaking or the engine is making popping or knocking sounds. 

5. Exhaust Fumes

If your oxygen sensor is not functioning properly, it can cause your vehicle's exhaust to contain high levels of unburned fuel and pollutants. This can lead to exhaust fumes that are darker than normal or have an unusual smell (smell of gasoline from exhaust). 

This harms the environment and can also be dangerous for you and your passengers. In extreme cases, it can even cause your engine to overheat.

6. Rough Idle

A failing oxygen sensor can also cause the engine to idle rough. This is because the sensor is not sending the correct signal to the engine control unit, causing the engine to run leaner than it should.

7. Reduced Engine Power 

Finally, a failing oxygen sensor can lead to reduced engine power. This is because the sensor is not sending the correct signal to the engine control unit, causing the engine to run leaner than it should.

If you notice that your vehicle is starting to experience performance issues, such as decreased power or acceleration, it could be a sign of a failing oxygen sensor.

What Can You Do When the Oxygen Sensor Is Malfunctioning 

If you think your oxygen sensor may malfunction, you must take your car to a mechanic as soon as possible to check it out. In the meantime, here are a few things you can do to help reduce the impact of a faulty oxygen sensor: 

• Avoid driving at high speeds
• Avoid heavy acceleration
• Don't tailgate other vehicles
• Keep your car's engine tuned up 

Conclusion

If your car's oxygen sensor is failing, it can cause a number of problems. The most common symptom is poor fuel economy, which can cause the check engine light to come on, or the car to run rough. If you notice any of these symptoms, you must take your car to a mechanic to have the oxygen sensor checked and replaced if necessary. 

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