What Happens to Sensors if They are Dirty?

On average, there are more than 30 individual sensors installed in modern vehicles on the road today. They range in sizes smaller than a quarter to the size of a rolled up dollar bill. Car sensors are typically used to collect data from various systems and relay it to the ECU. However, if the sensor is dirty, it's effectiveness can be compromised significantly.

If something’s malfunctioning on your vehicle and you have a mechanic inspect the issue, they may look at the sensor that has an impact on the problem. Checking to make sure the sensor isn’t dirty is one of the least expensive repair options but is the most common. By recognizing the symptoms of dirty sensors you can be better prepared to resolve these issues.

Oxygen sensor

Cars today have at least one oxygen sensor, and may have as many as four or five depending on the model. These sensors are prone to becoming dirty because they are located around the exhaust. Their job is to monitor how much unburned fuel is present in the exhaust system. When they are dirty, they may provide inaccurate information or none at all, which prevents the system from making changes in the air-fuel mixture to reduce the amount that is unburned. This will reduce the car's performance and the engine will have to work harder.

Manifold absolute pressure sensor

The MAP (manifold absolute pressure) sensor changes the voltage and frequency of the intake vacuum, depending on the air pressure in the manifold. When the sensor is dirty, it doesn't make the necessary changes, which slows down or speeds up the ignition timing. As a result, the car hesitates when you try to accelerate or go up an incline and has poor overall performance, even though it will continue to run.

Mass airflow sensor

The MAF or mass airflow sensor measures the volume and density of airflow to tell the engine how much fuel must be added. When the sensor gets dust or dirt on it, incorrect information can be sent to the diagnostic computer. The wrong amount of fuel is added, which can lead to stalling, sputtering, and hesitation as well as loss of power or lower fuel efficiency.

Wheel speed sensor

The ABS sensor or wheel speed sensor helps you maintain control of your vehicle when you need to brake or when you are driving on slick pavement. If this sensor gets dirty, it can cause the ABS light to turn on, indicating a problem when none actually exists.

In general, sensors that work with the engine impact the performance when they get dirty. The engine may sound rough, not run as well, or have less efficiency or power. For instance, the oil pressure sensor tells you when the amount of oil is getting low. If it’s dirty, it may not respond and you could run out of oil and damage your engine. Keeping your sensors clean is important to ensure optimal performance and a long life for your vehicle. If you ever have an issue with your car you think is related to a dirty sensor, contact a professional mobile technician from YourMechanic.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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