Determining Mass Air Flow Sensor Symptoms

A Mass Airflow Sensor (MAF) is made to report to the Powertrain Control Module (PCM), the amount of air entering the engine. The PCM then uses this to calculate the engine load and further deliver the correct fuel mass to the engine.

There are different types of MAFs. The most notable ones being the vane meter and the hot wire. None of these can work independently, to send air mass directly. Additional sensors are added to aid in this operation. However, the hot wire MAF sensor is the commonly used. It is the most preferred one because it comes in a smaller overall package and has no moving object. It is also less expensive compared to other airflow sensors. In addition, it has inbuilt temperature and pressure sensors. It also responds very quickly to changes in air flow, but at the same time, restricting low air flow.

How Does The Mass Airflow Sensor Work?

It consists of two wires, but only one gets heated up. The MAF also has a microprocessor inside which regulates the amount of air entering a fuel-injected internal combustion engine. This is solely dependent on the current required to keep the hot wire 200 degrees F hotter than the cold wire. Change in between the two wires causes an alternating decrease or decrease of the current, by the MAF, to the heated wire. This means that there will either be more air into the engine or less. There is also a mesh than smoothens out air flow. This is to ensure that the sensors have a steady reading.

Just like every other thing, constant use of something makes it wear out. For an MAF, it will become faulty at some point. When it goes bad, it prevents the engine from receiving the required amount of fuel. For proper functioning of an engine, a mixture of appropriate amount of air and fuel is paramount. Contrastingly, a bad MAF sensor will not be able to determine the exact volume and density of air, both essentials in the PCU unit adjusting fuel flow. The good thing is that noticeable symptoms of a bad MAF will help you to realize that it either needs cleaning or replacement. The symptoms include:



1. When the engine runs rich at idle or lean under load.

This will be an indication that the hot wire is contaminated. The contamination could probably be caused by dirt that gets attached to oil on the MAF from an over-oiled aftermarket air filter, a potting compound from the MAF sensor, spider webs, etc… because the hot wire does not need any insulation. This problem, however, can be easily corrected by cleaning.

2. When an MAF sensor reports either a higher or lower number.

This effects the engine directly to cause to run leaner or richer. Sometimes, you might find that the engine is in perfect functioning, but then your fuel is wasting away so fast. To be able to troubleshoot that an MAF sensor is the problem, you will need to visit a professional. The technician should first, check the whole circuit to ascertain the problem. This should further let him know whether to replace the whole MAF or not.

3. When an MAF fails completely and not send any report to the PCM.

This will make it impossible for the PCM to accurately control fuel, making the engine to either not idle completely, or do so roughly. In this case, the MAF requires replacement.

Since there are many causes of changes in fuel economy, be sure to visit a technician, a professional is preferred. This is one who will be able to troubleshoot the car problem and help you in solving.

There are also other symptoms that indicate that a sensor state is dwindling. However, the same problems also mimic a faulty fuel pump. They include- difficulty starting the engine, engine stalling and hesitation during acceleration.

Cleaning The Mass Airflow Sensor

The faulty sensor can both be cleaned and restored. But after excess damage, all one has to do is find a replacement. There are a number of ways that can be used to remove dirt from an MAF and restore it back to proper functioning.

  • The first method is to clean it with rubbing alcohol. Here, you will need latex gloves, a plastic freezer bag, a flat head screwdriver, rubbing alcohol and a towel. This will only take you 30 minutes. Put on the gloves and use the screwdriver to uninstall the sensor from the vehicle. Place the sensor in the plastic bag and pour the rubbing alcohol till fully immersed. Shake the bag vigorously and every 30 seconds if the MAF is cleaner. Once sure, remove the sensor and set it on a folded towel till dry. Only put the MAF back to the vehicle after the rubbing alcohol has fully evaporated.
  • Using an MAF sensor cleaner. This method might take you around 10 minutes. You will first need to check how your sensor has been anchored. If you see Torx screws, buy a Torx tool and a can of CRC Mass Air Flow Sensor Cleaner. Do not use any other cleaner as it could ruin your sensor. Carefully remove your sensor and disconnect the electrical connector. Spray 10-15 spurts of the cleaner onto the wire or plate. Do not scrub as this could damage the delicate parts. Leave it to dry completely before reinstalling it back to its place.
  • The electronic contact cleaner. Well, electrical cleaners are ideal for cleaning ignition components and other precision parts. It will help to remove dust, grease, dirt, oil, tarnish, and other deposits. This prevents arcing between dry contacts.

DO NOT clean your MAF with a carburetor or break part cleaners. This will malfunction your sensor as they contain aggressive chemicals.


A proper functioning MAF sensor is an essential to every driver. A clean MAF will renew MPG, increase horsepower, better fuel economy, better air/fuel ratio, your car will have fewer emissions, and finally, your engine will run smoothly. You can either do it yourself or book an appointment with your mechanic.

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