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The Importance Of A Cars Mass Airflow Sensor (MAF)

If you are having trouble starting your car, if it stops running shortly after starting or if the engine is hiccuping in general, there is a good chance that there is something wrong with the mass airflow sensor (MAF). A defective sensor can cause a multitude of problems, and it is important to keep this component clean. It may also help to understand its function in your vehicle.


What the Airflow Sensor Does

Mass airflow sensors are normally used on fuel injected engines. A car’s mass airflow sensor regulates the amount of air coming into an automobiles fuel injection engine. it submits that information to the engine control unit. The data is critical because it allows the ECU to administer the right volume of fuel to the engine. There are many problems that a bad MAF can create. Your engine is likely to run poorly if you do not get the problem fixed. 


Problems Caused by a Faulty Air Sensor 

If there is something wrong with your Mass Airflow Sensor, your check engine light should come on. The most common codes that will display are P0100 to P0105. 

 If it takes several tries to start your engine, it may be caused by a faulty sensor. If you hear a hiccupping or if there is a jerking during acceleration, your mass air sensor may be dirty or damaged. If a car hesitates or drags, or if it stops right after starting, it may be indicative of a problem.


How to Clean a Dirty Mass Airflow Sensor  

Depending on the make and model of your car, a new MAF may cost as much as $300.00. Therefore, it is a good idea to try to clean the air sensor if you can. You should clean it every six months. It is a good idea to take care of it when you clean your air filter. There are three simple steps to cleaning your sensor. 


Take The Sensor Out of the Car 

When you want to clean the MAS, open up the hood, and locate the air filter hose. You will see a small component attached to the hose that is connected to the cold air collector box this is the top of the MAS, but in order to work on it, you will have to remove the airbox. 

 The air collector box is an empty chamber on the inlet of most combustion engines. It gathers the air from the outside of the car and carries that air to intake filters that are attached to each cylinder. 

 To begin, you must take off the MAF wiring harness by pushing the clip down and pulling it off. The wiring harness is attached to the MAF with several colorful wires. You will then loosen the hose with a flat head screwdriver so you can get the airbox off. 

 On some cars, you will need a flat head screwdriver to remove the airbox, on others you can simply push down on a couple of side tabs and remove the box. 

 Once the box is off, you should look at the hole in the side that attaches to the air filter. You will find a small rod with a hole in the top of it. Inside the hole you should see two small wires, this is the mass airflow sensor. They are very tiny and when they are not clean, they can give you a bad reading. This component will not detach from the airbox.

 You should never touch the Mass Airflow Sensor when you are cleaning it. You should always use a cleaning product that is specifically designed for the MAS. No other cleaner will do. Spray the MAS for five seconds straight, wait about ten minutes for it to dry, and then spray it again. Turn it around and spray it on the other side. Wait until it is completely dry before putting everything together again. If cleaning did not solve the problem, you may want to take your car into a mechanic.


How the mass air flow sensor is tested?

In modern cars, the only way to test the mass air flow sensor is with a scan tool. Mechanics measure the amount of air flow (mass air flow sensor readings) at different RPMs. They compare the readings to the specifications or to the readings of a known-good mass airflow sensor.

Often mass air flow sensor readings are measured at idle, 1,000 RPM, 2,000 RPM and 3,000 RPM. A contaminated or bad air flow sensor will, in most cases, show lower air flow readings than a known good one. In some rare cases a bad sensor may show higher readings. Of course, different engines will have different readings. The air flow depends on the engine volume, so a V6 or V8 engine will have higher readings.

Low mass air flow readings do not mean the sensor is bad. A clogged air filter or plugged catalytic converter can also cause lower air flow sensor readings. Vacuum leaks affect air flow sensor readings too. That's why mechanics use a known-good sensor to compare the readings.


Sometimes a poor electrical connection at the air flow sensor connector could also cause the air flow readings to be out of range. For this reason, the air flow sensor connector terminals as well as the wiring needs to be carefully inspected.

Often if an air filter is not installed properly, or the air filter box is not closed, a piece of debris can get sucked into the mass air flow sensor and cause problems. Sometimes the debris can fall in during the air filter replacement. In this case, the repair is easy. The mass air flow sensor must be cleaned and the air filter must be reinstalled correctly or replaced.


Knowing When the MAF Needs to Be Replaced

Many car components will have a set life span and the owner’s manual will tell you when you need to replace certain components. The life span is determined by the number of miles a car has on it. The mass airflow sensor does not have such a life span. Theoretically, they can last for the entire life of the car. 

 As we have already discussed, the MAF is critical to a car’s performance. You would not be able to drive it safely and may not be able to drive the car at all of this sensor is not functioning properly. 

 These components are very easily damaged, which is why you should never touch the MAF when you are cleaning it. Remember, the MAF monitors airflow and that means that plenty of air is run through the tiny part every time you drive your car. 

 All that air can be hard on this delicate component. That air has dirt and other debris in it. The air filter is supposed to make sure that that debris does not make it to the surface of the MAF. Hence, it is necessary to keep your filter clean and tightly secured. You should replace the filter as the manufacture recommends.

 The PCV Valve is another important component of keeping the MAF safe. The crankcase holds your motor oil. It is located at the base of your engine. When you drive a car, waste gases are produced and those gases exit through the exhaust pipe. 

 Unfortunately, some of those gases do not exit, they get into the crankcase. If the PCV valve is blocked up, it can result in crankcase vapors backing up through the breather system. If the valve becomes corroded, it can create oily deposits on the MAF.   


Is it possible to drive with a faulty air sensor?

If you are strapped for cash, you may be wondering if you can drive your car at all with a faulty mass airflow sensor. You may be able to operate the vehicle for a short period of time, but it is advisable to get the part replaced as soon as possible. 

 A bad sensor will cause the engine’s computer to miscalculate the amount of fuel to inject into the engine. The engine will default to a generic fuel map that has no real way of knowing the correct amount of gas to inject.

 In most cases, the generic fuel map can cause an engine to, “run rich” and burn too much fuel. Not only will it cost you a lot of money at the gas station, but it may also destroy your engine.

 When your engine runs rich, the unused fuel has to have a place to go. The fuel that is able to get out of the engine, may cause the oxygen sensor to fail.  Eventually, soot will build up and get into the catalytic converter, causing the vehicle to run poorly. 

 A catalytic converter is an exhaust emission management component that lowers toxic gases and debris in the exhaust gas. When the converter gets too congested the car may not be able to run at all. 

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