What is a Mass Airflow Sensor?
A mass air flow sensor, or MAF, monitors the amount and density of air entering the engine. I’m guessing you could figure that out from the name, but not many know that its an integral component in most modern engines.
It is usually installed inside the intake air duct, between the air filter and the engine.
The MAF sends its measurements to an engine control unit (ECU), which then uses that data to calculate when to deliver fuel, how much, and when to generate a spark. The MAF is sometimes used in conjunction with an O2 sensor that provides a “closed-loop” feedback in order to make corrections to that predicted air mass.
Engines need a proper blend of air, fuel, and combustion to run efficiently. So a properly functioning MAF is crucial to a smooth ride.
|GLI||2000 / 2013|
|Jetta||2000 / 2004 / 2012 / 2013|
|Passat||2000 / 2001 / 2007|
What Causes the MAF to Fail
Like anything mechanical or electrical, a MAF tends to wear down over the years. And while MAF problems aren’t specific to Volkswagen, it does feel that their tend to just wear down a lot faster.
Of course, any MAF will start failing if it gets too dirty to do its job. If an owner doesn’t regularly replace their air filter (or replaces it with a cheapo-version) it can cause a buildup of air impurities on the MAF.
What Happens When the Sensors Start Failing?
- The engine is hard to start
- The engine stalls or misfires
- Poor acceleration characterized by hesitation or “jerking.”
- Poor idle performance
- A negative effect on fuel economy
- A constant, headache-inducing, retina-burning warning light that will haunt your dreams (is it obvious I’ve had this problem before?)
Cleaning or Replacing the MAF
While you can clean a dirty MAF, in many instances its easier to just replace the unit.
A MAF at a dealership can cost anywhere between $75—$150 dollars, with labor costs adding another $150 to that total. You can try and clean the mass air flow sensor yourself by following the instructions in this article:
File Your Complaint at CarComplaints.com
CarComplaints.com is a free site dedicated to uncovering problem trends and informing owners about potential issues with their cars. Major class action law firms use this data when researching cases.
Notify the Center for Auto Safety
The Center for Auto Safety (CAS) is a pro-consumer organization that researches auto safety issues & often compels the US government to do the right thing through lobbying & lawsuits.
Report a Safety Concern to NHTSA
The National Highway Traffic Safety Administration (NHTSA) is the US agency with the authority to conduct vehicle defect investigations & force recalls. Their focus is on safety-related issues.
Spread the Word
Social media is all the rage these days. And for good reason – it can help spread a message quickly. So get out there and start spreading this page.
“I thought I might be able to get away with driving around with the faulty part, but found out a malfunctioning MAF can lead to stalling, misfiring, poor fuel economy or bad acceleration. $100 for the part and $75 for the labor later I was on my way. Until a few days later when the MAF sensor malfunctioned again.”
“I've never had a problem with this in other makes of cars, but for my VW Passat, it seems like I need to replace it every 3 years. VW extended the warranty to 7 years for Mass Airflow to 7 years for new cars, but for existing VW owners, there is nothing we can do about it except replace it.”
“The code for MAF sensor is on all the time, and you can tell it's really affecting the performance of the car. It drives weird at high speeds, feels like I'm constantly going over small bumps. Gas mileage isn't as great, either. I've seen videos and sites claiming just to clean it, but I'm afraid it won't work.”