Mass Air Flow sensor (MAF or also MAS) measures the amount of air that comes into the engine's combustion chamber to be mixed with fuel. This sensor basically sends extremely important information to the engine control unit. According to that information the ECU sends the needed amount of fuel to combustion chamber to ensure that the air-fuel mixture is OK. Here, Wikipedia says a lot about the principles of this sensor's work.
Today, we'll look at main symptoms of bad MAF sensor and we'll also describe why it can die and what you can do to prolong its life.
These are the symptoms of MAF sensor death
- The engine starts after a very long rotation only. Starter may rotate the engine for a dozen of seconds until it finally starts.
- In 5-7 seconds after starting the engine may stall. The mixture is incorrect and this causes stalling.
- The idling rotations are not stable. If you look at tachometer, the arrow may jump around 1000 RPM mark.
- The engine shakes and nearly stalls when idling. Sometimes the rotations will be so low, it may seem that the engine will stall right now.
- The car jerks during acceleration. The engine may hesitate when you push the gas pedal, and then in the process of acceleration it will nearly stall at some points.
- Engine may also hiccup. It's easy to see if you open the hood and watch the engine when it's idling. The hiccups will be seen with vibration and shakes.
- Rich or lean mixture will cause wrong idle rotations. They may go up to 2000 RPM or go down to 400-500 RPM.
- Engine power will be lost. The vehicle may go OK, but when you try to accelerate, it will start shaking, stalling, hiccupping and making all other kinds of things.
- Poor fuel economy. One more thing is that the fuel consumption will grow up rapidly. The ECU won't know how much fuel it should send, so it may work in emergency mode.
Is it safe to drive with bad MAF sensor?
It's not very safe for your engine, because it works in conditions that are far away from being optimal. But in most cases, you can drive your vehicle to the service station without calling a tow truck service.
If you see Check Engine sign flashing on your dashboard, it can be a trouble. The mixture became too rich or too lean to drive, and this causes problems to catalytic converter and other parts of your car.
Also, it's a bad idea to drive a car that has all symptoms mentioned above along with black smoke from exhaust pipe. It means a lot of fuel isn't burned in the combustion chamber. It goes to catalytic converter and to exhaust system and burns there causing bad effects on these parts.
How to fix the MAF sensor?
You can try to clean the sensor, but experts say it will help for some short period of time only. Cleaning is possible with rubbing alcohol or with special MAF sensor cleaner from any car shop. If the sensor is broken, cleaning won't help, and you'll need to buy a new one.
To replace the MAF sensor, you'll need to open the air-filter box, use the screw driver to pluck it out, install the new unit and try if it works. Don't forget to disconnect the battery before you do any other work.
About the authors
The CarAraC research team is composed of seasoned auto mechanics and automotive industry professionals, including individuals with advanced degrees and certifications in their field. Our team members boast prestigious credentials, reflecting their extensive knowledge and skills. These qualifications include: IMI: Institute of the Motor Industry, ASE-Certified Master Automobile Technicians; Coventry University, Graduate of MA in Automotive Journalism; Politecnico di Torino, Italy, MS Automotive Engineering; Ss. Cyril and Methodius University in Skopje, Mechanical University in Skopje; TOC Automotive College; DHA Suffa University, Department of Mechanical Engineering
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