How to Service Toyota Mass Airflow Sensors

The Toyota mass airflow sensor uses a pair of specially coated wires that change resistance as they are cooled by air flowing through the sensor. One wire stays at a constant current and the other is at a constant resistance, and the difference between the two is used to calculate total air mass entering the engine. This, along with other load sensors, is used to calculate the needed fuel. Over time the sensor can get a buildup of contaminates that act to insulate the wires. You must clean this off to maintain accuracy; it is a common service on Toyota mass airflow sensors.

Difficulty:

Moderately Easy

Instructions

things you'll need:

• Screwdriver set
• Mass airflow sensor cleaner

1. • 1

     Remove the sensor by first removing the flexible bellows attaching the air box to the throttle body. Loosen the clamps with a screwdriver, then slip the bellows off the air box and the throttle body.

   • 2

     Remove the lid from the air box by releasing the hold-down clips and lifting up. Disconnect the electrical connector from the mass airflow sensor, and move the assembly to a work bench.

   • 3

     Pull out the two retaining screws from the sensor, and carefully remove the sensor from the air box. Take care not to damage the sensor. Put the rubber O-ring seal in a safe place until you have reinstalled the sensor.

   • 4

     Clean the sensor with mass airflow sensor cleaner. Use only a cleaner formulated for mass airflow sensors; common carburetor spray will damage the coating on the wires.

   • 5

     Reinstall the sensor into the air box, and install the air box into the Toyota. Plug the electrical connector into the sensor, and reinstall the bellows that you removed in Step 1. Start the engine and test-drive the vehicle.