Mass airflow sensors measure the amount of air by weight through changing voltages or frequencies and sends this information to the onboard computer. The computer uses this and other inputs to calculate the correct amount of fuel delivered. Symptoms of failure include poor starting, engine surging, engine stalling, a check engine light, and no-start conditions. Sensors are non-serviceable, replace sensors that are non-functional. Walker Products began supplying the fuel system needs of the automotive industry in 1946. Today Walker is one of the largest, privately owned manufacturers of fuel system components and engine sensors, and has served the needs of the worldwide automotive aftermarket. We are committed to supplying products manufactured to meet or exceed OEM standards and specifications. This effort is backed by our own manufacturing, product management and engineering staff to ensure it is maintained and accurate in the production of quality parts, vehicle applications, instruction sheets and technical support. Our products include Carburetor and Fuel Injection Repair Kits, Oxygen Sensors and other Engine Management products such as Throttle Position Sensors, Cam and Crankshaft Sensors, Fuel Injectors, Spark Plug Wires and Gaskets. As an ISO 9001:2015/TS16949 certified company, we are committed to supplying the highest quality products. Vehicle Fitment: Chevrolet T6500 2009-2004, T7500 2009-2004, W3500 Tiltmaster 2008-2005, W4500 Tiltmaster 2008-2005, W5500 Tiltmaster 2009-2005, GMC T6500 2009-2004, T7500 2009-2004, W3500 Forward 2008-2005, W4500 Forward 2008-2005, W5500 Forward 2009-2005, Isuzu NPR 2008-2005, NPR-HD 2008-2006, NQR 2010-2005, NRR 2010-2005, Lexus GX460 2017-2010, GX470 2009-2005, LX470 2007-2005, LX570 2011-2008, LX570 2017-2013, Toyota 4Runner 2010-2005, Land Cruiser 2011-2005, Land Cruiser 2017-2013, Prius 2017-2016, Prius Prime 2017, Sequoia 2017-2005, Tacoma 2017-2005, Tundra 2017-2005