The Bosch 028021807H Mass Air Flow (MAF) Sensor is a precision-engineered component designed to accurately measure the volume of air entering your engine's intake system. This hot-film air mass sensor uses advanced micromechanical technology with a heated sensing element to provide the engine control unit (ECU) with critical data for optimal fuel injection and engine performance. Key Features: Hot-film sensor technology with ceramic substrate and thick-film resistors for precise air mass measurement 5-terminal electrical connector with bolt-on mounting design Maintains constant overtemperature above ambient for accurate readings independent of air temperature Complete sensor unit with housing—sensing elements are paired and calibrated on the production line Wear-free operation with no moving parts for long-term reliability Wide measuring range with high sensitivity to detect even small changes in airflow OEM quality from Bosch, a global leader in mass air flow technology This sensor cross-references to OEM part number 077133471M. A properly functioning MAF sensor is essential for maintaining optimal fuel efficiency, reducing harmful emissions, and ensuring smooth engine performance. Signs of a failing MAF sensor include rough idle, increased fuel consumption, poor drivability, and elevated emissions.