The MAF (mass air flow) sensor is a simple but extremely important device on many modern cars. The MAF sensor is part of the air intake system of the engine and is responsible for sending a signal to the engine's computer that tells the computer how much air is being delivered to the motor. If the MAF sensor becomes contaminated with dirt, the poor signal can cause rough idling and even a "check engine" light, which means that the sensor may need to be removed for cleaning or replacement.
Locate the air intake tubing and the air box of your particular vehicle. Consult a workshop manual if necessary. The intake is generally located on the passenger's side of the engine. There is a section of tubing that goes from an air box to the intake manifold. The MAF sensor is located between the air box, which contains the air filter, and the throttle body for the intake manifold.
Remove the air box if necessary. This will not need to be done on all vehicles. Disconnect any tubes or inlet pipes (more common on turbocharged vehicles) that attach to the air box. The tubing and inlet pipes will be held on with hose clamps that are loosened with a screwdriver. Disconnect any wiring harnesses as well. Remove the air box and air filter from the engine bay.
Remove the MAF sensor and housing. The MAF housing is usually bolted to the engine bay with a couple of bolts that are removed with a socket and ratchet. You also will need to remove any intake tubing that is fastened to the MAF, usually held on with large hose clamps that are loosened with a screwdriver.
Carefully remove the MAF sensor from the engine bay, being very careful not to damage it. Clean it with MAF sensor cleaner and replace it back inside.