1. Open the hood of your Lexus ES 300.
2. Locate the air filter box. It is a black plastic box located on the passenger side of the engine bay.
3. Remove the air filter box cover by unlatching the clips and lifting it off.
4. Inside the air filter box, you will see the air intake hose.
5. Follow the air intake hose towards the engine.
6. The MAF sensor is located on the air intake hose, near the throttle body.
7. The MAF sensor is a small, cylindrical device with a wire mesh screen. It is usually held in place by two bolts.