The air mass meter in the car is an indispensable sensor for engine control. This is not only used in diesel engines, but also in petrol engines. It is located right where the action is and is usually installed in your intake manifold. In order to understand its function, you should not only know the measured parameters, but also the wiring diagram of your mass air flow sensor. In this article, we explain the necessary basics in detail before we begin to show you how you can identify a corresponding defect in this component.
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The function of the air-mass_sensor
This component has a related component with which it is often confused because the term air flow meter sounds very similar. Your air mass meter is not only able to determine the flow rate of the intake air, but also measures its temperature and humidity at the same time. All three parameters are important for your engine control unit, because it has to calculate the fuel injection quantity at all times so that your vehicle engine can work optimally. In addition, the measured values are also necessary in order to control the exhaust gas recirculation, if present, more precisely. The air flow meter was a sensor that was used in older vehicle generations. This was not able to measure multiple parameters, only determining how much intake air was going to your engine. In today's vehicle models, there are two different variants of the air mass meter with different pin assignments. The two versions are referred to as hot-wire or hot-film air mass meters. In the former, a heated wire serves as the measuring electrode, with a temperature of around 100 °C. The measurement is based on the cooling of the wire or by determining the time it takes to bring the wire back to 100 °C. With the hot film components, the measurement is carried out with the help of flat platinum electrodes on ceramic elements, so that heating resistance, temperature resistance and sensor resistance can be measured. The sensor temperature for this type of component is around 160 °C. With the older hot-wire air mass sensors, particles in the exhaust gases can be deposited, so that they have to be burned regularly at around 1,000 °C. So before you pull the plug off your air mass meter, you should find out which type of component and which component was installed in your vehicle. This can save you a lot of time and eliminate unnecessary guesswork.
What are the symptoms of a faulty mass airflow sensor?
A failure of this component is almost always associated with a significant loss of performance. In addition, the vehicle's emissions levels also deteriorate, but you may only notice this when the next emissions test is due. Ultimately, both of the described symptoms of the defective air mass meter arise from the fact that this component no longer supplies correct measured values to your engine control unit. As a result, this incorrectly calculates the fuel quantities to be injected, which means that your engine cannot work in the optimum performance range. In addition, such a problem is also noticeable in fuel consumption, because this, as a rule, also increases significantly. If the engine speed changes constantly when idling, this can also indicate a defect. Because the air-fuel mixture in the engine cylinders is too rich or too lean, misfiring can be the result. The same applies to your exhaust gases, which can turn into black smoke. Ultimately, it can even cause your power pack to switch to an emergency program.
If you notice one or more of the symptoms of an air mass meter defect, which we have described, this can also have completely different causes. With a petrol engine, you should always remember to check your ignition system. The same applies to a failure of the turbocharger.
What are the causes of a defect in the air-mass_meter?
Ultimately, this component from the engine intake tract is a component that is subject to continuous wear. Therefore, sooner or later it has to be renewed for every vehicle. If the engine performance has decreased significantly and your vehicle has a high mileage, you should also check your air mass meter. If you drive frequently in heavy rain, it can also get past the engine air filter and get to the sensor. Water, but also oil vapors from your crankcase lead to accelerated wear of this component. If your intake duct leaks, dirt and sand particles can also lead to damage.
How do you check the mass airflow sensor?
In order to take a closer look at this component, you first need to know where it is located. The sensor in the intake system is usually installed directly behind the engine air filter. There you can easily remove it after you have pulled the connector off the air mass meter. As part of a visual inspection, many defects can already be discovered with the naked eye. The same applies to coarse contamination, which often occurs with hot-wire components. In addition, it is advisable for modern vehicles to use the error memory and read it out, because this is how many errors can be identified without a doubt. However, a component defect does not always have to result in an entry in the error memory, so it can sometimes be necessary for the sensor to be replaced as a preventative measure.
Conclusion
Modern vehicles integrate a variety of sensor data in the engine control unit to ensure optimal engine operation. This offers you the opportunity to achieve an increase in performance through chip tuning or to reduce vehicle fuel consumption. In order for the engine electronics to work properly, your air mass meter, for example, must not be defective. In this article you have learned what symptoms a component failure can cause and also how to check this component. Now you can decide for yourself whether you want to replace the sensor yourself or give a specialist workshop the corresponding order.
A tip from CarTipsandmore: If you have problems with your air mass meter, you can it may be sufficient to clean the sensor once. This may allow you to restore its functionality. This applies in particular if the system used is a component with a hot wire, since exhaust gas particles can then be deposited and impair its function. A suitable special spray is recommended for cleaning your air mass meter. To do this, remove the sensor (this can usually be found behind your air filter), clean it and reinstall it after it has dried completely. If you cannot restore the function with this, the component can still be changed afterwards.