Some of us change the the stock filters to filters which require oiling. Sometimes if you put too much oil onto the filter, some of that oil gets stock to the MAF sensor wires and that causes the CHECK ENGINE light.
But don't worry, you don't have to replace your MAF unit when that happens. They only require cleaning. But how do you clean it ??
Picture one shows the location of the MAF sensor and housing directly behind the air box.
Unhook the wiring harness from the MAF. You will need a T-20 tamper proof torx bit to remove the 2 screws. Click here to buy one online! (NOTE: a pliers will also work, but not recommended)
Carefully remove the sensor from the housing, you will see the small wires shown in picture two.
Try avoiding solvents that leave residues: like the aromatics [toluene, xylene] Use electrical parts cleaner or Windex and a Q-tip to gently scrub the wires clean. Acetone, methelyene chloride or chloroform will also work well. (NOTE: It has been said that carburetor cleaner is too harsh to use).
The Q-tip method is recommended when the sensor wires are really dirty and simply spraying cleaner on them will not clean them. Be very careful when using a Q-tip!
Use a Q-tip and gently scrub the wires. If the MAF wires are not really dirty you shouldn't need to use a Q-tip. BE GENTLE when scrubbing on the bobbins. Just spray the wires and let dry. If there is still gunk on them - use a q-tip to clean them. If you break a wire you are screwed. Do Not scrape with anything. The wires wound around the bobbin are extremely fine.
When the MAF sensor is clean re-insert it into the housing and snug down the screws and re-connect the wiring harness.
Additional Help from Richard M: "The sensor element is basically a ceramic bobbin wound with the resistive wire and then coated with glass like material. Solvents have not shown any harm to the coating. One thing to note is that you can bend the wires that are welded to the leads so that the element is no longer centered off the leads. Make sure to recenter it."