Car Tips

Why Your Car Keeps Failing Emissions Tests

Why Your Car Keeps Failing Emissions Tests

Every registered car has to pass an emissions test. This is part of the annual or bi-annual safety assessment program to ensure vehicles are safe to use on highways and roads, and the emissions test is one of the many examinations that are conducted here. If your car fails to pass the test you’ll end up with car inspection sticker, plus you will be required to undergo the test again in 30 days. If you’re having problems passing the test, here are the most common reasons.

Exhaust Leak

A leak in the exhaust system is going to cause a lot of problems ranging from dirty gas fumes, pedal vibrations, increased engine noise to reduced fuel efficiency. One or all of these problems will mislead the car’s oxygen sensor and cause an inspection failure.

O2 Sensor is Malfunctioning

If your car’s oxygen sensor is not working, it won’t be able to determine the level of oxygen present in your exhaust gas. This could lead to high levels of toxicity in the fumes that are released from the tailpipe. This alone will lead to a failing grade during the test, but in addition, a malfunctioning O2 sensor cuts back engine power and makes your fuel inefficient. If the situation is not handled properly this could lead to engine overheating, so before going to the emissions test have your O2 sensor checked and if necessary, replaced. Make sure to check out our post on the benefits of car oxygen sensors.

Incorrect Fuel Metering

Some car components are designed to work together to ensure the right amount of fuel is burning properly. But if the fuel injection unit, engine control unit or the carburetor doesn’t work, the results of the metering could be compromised, burning more gas than what is required. As you might expect, a car that burns more gas and fuel than necessary will fail an emissions test so have the matter looked up thoroughly.

Running Rich

A rich fuel mixture could be another reason, as the presence of too much carbon monoxide in the exhaust fumes causes the car to burn more gas than is necessary. There are many possible reasons for this such as the aforementioned bad oxygen sensor, the mass airflow sensor isn’t working, excessive pressure or leaking fuel injectors.

Since there are a lot of possible reasons, it’s best to have a licensed technician check your car’s components and make sure everything’s all right. By having these inspected, you’ll have a better chance of passing the next emissions test. Make sure to check out our post on why regular car maintenance is very important.

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