This is an often overlooked maintenance item because most maintenance protocols do not specify an interval for cleaning the mass airflow sensor. However, it is important as a dirty mass airflow sensor will reduce your fuel economy, throttle response, and engine performance. Mass airflow sensors are located after the air cleaner, but before the throttle body. Although the air filter will remove harmful particles in the air, some particles make it past the filter and contaminate the mass airflow sensor. This build up is caused by a few things such as dirty air leaking past the air filter and oil being sucked into the intake via the PCV hose. I recommend cleaning the MAF sensor every time the air filter is cleaned for maximum performance. This is usually every 15,000-30,000 miles. It’s a simple enough task that is worth the preventative measure.

Here is the typical procedure for cleaning the Mass airflow sensor::

1)Remove the wiring harness from the MAF sensor. There may be two pigtail connectors in the same vincinity. One is usually the Intake Air Temperature Sensor, the other is the MAF sensor connector which is located just after the air filter and before the throttle body.
2) Remove the air filter and intake boot. This may be connected by latches and/or hose clamps. Remove the air boot from the throttle body.
3) Remove the MAF sensor from the intake boot. Do not touch the actual sensor element. It is very sensitive and can be damaged easily.

4) Use only “Mass Air Flow Sensor Cleaner” available at the auto parts store. Do not use brake cleaner or carburetor cleaner as they will leave a residue on the sensor wire. Follow the instructions on the can. Allow the part to dry before re-assembly.

5) Your vehicle may not respond to the MAF cleaning immediately! Modern fuel injected cars have a fuel/air map that determines the correct amount of fuel to deliver to the engine based on the airflow the MAF determines. However, this pre-programmed map is adjusted throughout the life of the engine to take into account the wear of many parts. It does this by something called “fuel trim”, which increases or decreases fuel usage based on the information the computer is receiving from the MAF sensor, the oxygen sensor and other sensors. Long term fuel trim is something that may take a day or two of driving to fully adjust to your clean MAF sensor.