Signs My Car’s Oxygen Sensor Is Malfunctioning

Your car, truck, or utility vehicle’s oxygen (O2) sensor is located in the tailpipe. Its job is to measure the amount of oxygen being released in your automobile’s exhaust. Based on its measurements, your vehicle’s engine control unit will make adjustments to the combustion chamber’s air and fuel mixture to ensure your engine is running as efficiently as possible. The oxygen sensor can go bad, especially if you have over 100,000 miles on your car. Advanced Automotive lists the signs of a failing O2 sensor below.

Check Engine Warning

A bad oxygen sensor is a primary reason why your check engine light will come on and not turn off. In fact, until the oxygen sensor is replaced, the light will stay on and your vehicle will fail any emissions tests it takes. One reason why your vehicle won’t pass the emissions tests is that you have too much carbon in the exhaust if the O2 sensor is creating a rich fuel mixture in the combustion chamber.

Gas Mileage Reduction

If a malfunctioning O2 sensor is creating an imbalance in the air and fuel mixture, your vehicle’s gas mileage will also suffer. It doesn’t matter if there is too much or not enough air in the mixture. The engine will have to work harder and, as a consequence, it will burn more fuel.

Black Exhaust Smoke

Black exhaust smoke is also a sign of a rich fuel mixture. Your engine burns any excess fuel in the combustion chamber and this can create black exhaust smoke and even sparks or flames if there is a ton of excess fuel. This is a dangerous situation in the engine, as you can imagine, so it’s important to get the source of excess black exhaust fixed as soon as possible.

Sulfur Odors

This sign of a malfunctioning oxygen sensor can also be a symptom of sudden catalytic converter failure, which can be a very bad thing. You might smell a rotten egg odor in your exhaust. This is sulfur. If you smell rotten eggs in your exhaust or coming from your engine, have the problem fixed right away. If the issue is the catalytic converter, you risk carbon monoxide poisoning.

Engine Performance Trouble

Finally, if the O2 sensor is reporting wonky oxygen numbers and the engine control unit adjusts the combustion mixture when it shouldn’t, your engine performance will suffer. The engine might buck, hesitate, hiccup, skip, sputter, or surge. You may also notice problems when you press down on the accelerator; the engine might hesitate before picking up speed.

Schedule an appointment with Advanced Automotive in Stanwood, WA, if you are experiencing any of the signs listed above. We’ll check your O2 sensor and if it isn’t the problem, we’ll find the problem.

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