Bosch 028021808M Hot-Film Air-Mass Meter MAF Sensor

The Bosch 028021808M Hot-Film Air-Mass Meter (HFM) is a precision mass air flow (MAF) sensor engineered to accurately measure the volume and density of intake air entering the engine. As a direct OE-quality replacement, this sensor delivers the exact air mass data the engine control unit (ECU) requires to calculate optimal fuel injection timing and quantity.

How It Works:

Intake air flows over a heated sensor membrane inside the unit. Resistors on two defined measurement fields record the resulting temperature differential — the greater the airflow, the larger the temperature difference. An integrated electronic module processes this data and transmits a precise air mass signal to the ECU in real time, enabling efficient combustion and proper engine management.

Key Features:

• Bosch OE hot-film technology for precise, stable air mass measurement
• Integrated electronic signal processing module with digital signal filtering
• Compact plug-in sensor design for straightforward installation
• Rapid response time to changing air flow conditions
• Low power consumption with high measurement accuracy
• Reverse-flow (return-flow) detection capability
• Built to OEM fit, form, and function standards

A faulty or contaminated MAF sensor can trigger check engine lights, cause rough idling, poor fuel economy, and hesitation under acceleration. Replacing it with a genuine Bosch unit restores proper fuel metering, reduces harmful emissions, and returns the engine to peak performance. Bosch part number 028021808M — also referenced as part of the 0280218 HFM sensor family.