© Winai Tepsuttinun/Shutterstock.com
Mass air flow sensor
DIY difficulty: Easy
Function: It measures air flow entering the engine and sends that information to the engine computer, which regulates fuel injection, the ignition system and transmission shifting. When it gets dirty, the information it sends isn't accurate, affecting fuel economy.
RATE SEARCH: Thinking about getting a new car? Compare auto loan rates at Bankrate.com today!