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Why Did My Car Fail the Emissions Test Because of the Oxygen Sensor?

There are numerous answers to the titled question that we are going to give below. We are Rick’s Auto Center and we can replace your vehicle’s oxygen (O2) sensor when it goes bad. Unfortunately, your car, truck, or utility vehicle will not pass an emissions test if the oxygen sensor is malfunctioning. Here are the reasons why the vehicle will receive a failing grade.

Illuminated CEL Warning

One of the first things that happens when the O2 sensor goes bad is the CEL or check engine light turns on on the dashboard. It is important to understand that no matter the reason why the CEL is on, your vehicle will not pass an emissions test with an illuminated check engine light.

Performance Problems

Another thing you will notice with a faulty O2 sensor is engine performance problems. The engine will either sputter or surge. Respectively, these problems are caused by too much air or too much fuel in the combustion chamber. This happens when the main computer chip makes unnecessary adjustments based on the data it receives from the malfunctioning O2 sensor.

Reduced Fuel Efficiency

Unfortunately, when the engine is not running efficiently, you cannot expect to get good gas mileage out of your automobile. Consequently, until you replace the bad O2 sensor, you are going to notice a reduction in the fuel efficiency that your car, truck, or utility vehicle gets.

Burning Sulfur Exhaust Odors

You may also start to detect burning sulfur odors in the vehicle’s exhaust, and this, too, can cause your automobile to fail the emissions test. These odors are caused by a clogged catalytic converter that is being overworked by the excess hydrocarbons found in the exhaust.

Black Exhaust Smoke

Excess fuel in the combustion chamber causes the increase in the number of hydrocarbons found in the exhaust. Consequently, the catalytic converter may also be left unable to treat the exhaust. When this happens, and when the engine burns away extra fuel, it will release black exhaust out of the tailpipe. This exhaust can cause your vehicle to fail the emissions test.

Increased Emissions Levels

Coming full circle, the excess hydrocarbons caused by the malfunctioning O2 sensor increase the emissions in your vehicle’s exhaust and this is why it fails the test. Your best bet is to have your automobile inspected before you take the emissions test if the CEL is on.

Rick’s Auto Center in Hamden, CT, is here to help, so give us a call today.

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