How to Clean A Mass Air Flow Sensor

Updated: Mar. 01, 2024

Cleaning, rather than replacing, a MAF sensor is quick and easy and can save you $300.

Next Project

20 to 30 minutes






Over my 50-year career in the auto repair industry, I replaced thousands of defective, contaminated, shorted or simply-worn out mass air flow sensors (MAF).

I first saw them when Oldsmobile Division began switching to electronic fuel injection in the early 1980s. In those days, new cars still on car carriers wouldn't start because of defective MAFs. Consequently, all dealership technicians got a crash course in what an MAF does, the symptoms of a bad or failing sensor, and how to understand their specific diagnostic trouble codes (DTC).

After leaving the industry to become a vocational educator, I spent one summer at a Ford electronics facility as part of an "Educator in the Workplace" internship. As an auto technician, it was fascinating to see how car parts are designed, manufactured and tested.

One department I visited tested empty MAF sensor housings before electronic components were installed. Sophisticated measuring devices ensured the housings were the correct size to 1,000th of an inch and there was no slag on any seams. All for an empty shell that cost less than a dollar!

Once all the electronics were installed, the MAF sensor went through another series of tests. That's because MAFs are one of the most critical sensors needed to make our vehicles run and perform efficiently and run smoothly.

According to auto repair expert Bernie Johnson, "Today, MAF sensors are one of the most reliable parts on our cars and trucks." However, they do get dirty, and that's where MAF sensor cleaners come in. Here's what you need to know.

About the Expert

Bernie Johnson has almost 50 years of experience in the auto repair industry as an Automotive Service Excellence (ASE), Oldsmobile and Hyundai master technician. He is also a state certified emissions and safety inspection inspector at Faulkner Hyundai in Philadelphia, Pennsylvania.

Keep Yourself Safe

Make sure the engine and sensor are cool, and the engine is off. Wear personal protection equipment. Read and follow all label safety instructions and directions when using spray MAF sensor cleaners, which are highly flammable. Work outdoors in a well-ventilated area.


What is the mass air flow sensor?

A device that monitors the temperature and weight of air entering your engine. Your onboard computer (engine control module, aka ECM) needs that information to calculate the right amount of fuel for the engine to run properly under all operating conditions.

What does the mass air flow sensor do?

It heats a small, hot, delicate platinum wire or plate, then measures the current required to keep it at a constant temperature while air blows past it. The MAF sensor sends that information to the ECM, which then determines how much fuel to inject into the combustion chamber.

What happens when the mass air flow sensor is dirty?

Over time, dust, debris and oil particles stick and bake onto the hot wire/plate. Eventually, those particles insulate the wire/plate from the air stream. This causes drivability problems, makes the Check Engine Light (CEL) illuminate, and increases tailpipe emissions.

What are the signs of a failing mass air flow sensor?

Hard starting, stalling, rough idling, poor acceleration, black smoke from the exhaust, as well as poor gas mileage. A rotted-out or rusted MAF sensor hot wire/plate can keep your car from starting and needs to be replaced.

How much does it cost to replace the mass air flow sensor?

It depends. In my area (outside of Philadelphia, Pennsylvania) it runs from $300 to $375 — about $100 for labor and $275 for parts. (According to AAA, national labor rates range between $47 and $215 an hour.) This doesn't include diagnostic or other fees.

Tools Required

  • 4-in-1 screwdriver
  • Torx or hex sockets and ratchet (depending on how the sensor is attached)

Materials Required

  • Disposable or work gloves
  • Disposable towels
  • Dust mask
  • Fender cover
  • Mass Air Flow Sensor cleaner
  • Safety glasses

Project step-by-step (5)

Step 1

Getting started

  • Gather all your tools and materials.
  • Put on your gloves and eye protection.
  • Install the fender covers to protect the paint finish.
  • Before starting, use your phone camera to record the sensor position and electrical connections for reference later.
  • Locate the MAF sensor. It’s usually in either:
    • An air duct between the air filter housing and the throttle body;
    • Between two rubber or plastic air filter housing ducts or air intake snorkels (which look like accordion pleats).
  • With disposable towels, wipe away any loose dirt or dust from the MAF sensor, as well as all air ducts.

Closeup of Mass Air Flow Sensor in a carBob Lacivita for Family Handyman

Step 2

Remove the MAF sensor

Take your time removing the sensor. Parts are plastic. They become brittle over time and can break.

  • Carefully remove the MAF sensor’s electrical harness connector’s retaining locking clip. (Not all MAF sensors have these.)
  • Depending on the type of sensor, squeeze or pull up on the electrical connector and remove it from the sensor. Cover and secure the harness and connector out of the way.
  • Take a screwdriver and loosen (do not remove) any clamps securing the MAF sensor to the air ducts and/or the air filter housing cover.
  • If the MAF sensor is stuck onto the duct, carefully run a small screwdriver or pick between the sensor and the duct to loosen the bond.
  • Depending on the type of air filter housing your car has, release the spring clamps, screws or bolts securing the air filter housing cover to its base.
  • Lift the air filter cover, then slide off the air duct.
  • The MAF sensor can now be:
    • Slid out of the duct.
    • Unclipped or unbolted from the air duct.
    • Unbolted from a bracket and then removed from the duct.

Pro tip: Check and clean the air filter box of dust and debris and replace the air cleaner whenever cleaning the MAF sensor.

A person checking engine while wearing glovesTMB Studio

Step 3

Clean the MAF sensor

Using a MAF sensor cleaner:

  • Check the MAF sensor’s inlet screen for dirt or debris. (Not all MAF sensors have inlet screens.) The screen smooths and straightens intake air before reaching the MAF sensor’s hot wire or plate.
  • Spray 10 to 15 spurts of the MAF cleaner onto the hot wire or plate. Never touch the hot wire or plate with the spray cleaner straw or anything else. If your sensor has a screen, use the cleaner to clean that as well.
  • Inspect air inlet ducts or air intake snorkels for cracks or splits. Johnson says that’s the biggest problem he sees with MAF sensors. “[Broken air intake ducts or snorkels] cause the Check Engine Light to come on due to a lean fuel air mixture, while also allowing excess dirt to accumulate on the inlet screen and sensor [hot] wire,” he says.
  • Don’t scrub any internal parts. If you do, you may break the hot wire or damage the plate.
  • Allow the MAF sensor to air dry completely before reinstalling.

Pro tip: Never use brake cleaner or any other type of cleaner on the MAF sensor. They can leave unwanted residue, ruining the sensor. Only use cleaners specifically for MAF sensors.

A person cleaning the Mass Air Flow SensorTMB Studio

Step 4

Reinstall the MAF sensor

  • One the sensor is dry, reverse the above steps to reinstall it.
  • Start the engine to see if it’s running smoothly, or if the CEL illuminates.

Black Mass Air Flow Sensor place on a surfaceBob Lacivita for Family Handyman

Step 5

What happens if my car still runs rough or the CEL is on?

Warning light engine in car dashboardIvan Las Heras/Getty Images