Rick's Free Auto Repair Advice

Multifunction Intake Air sensor

New Mass Airflow Sensor – MAF
Mass Airflow Sensors (MAF) are designed to calculate the mass of the air entering the throttle body. It does this by forcing air across a hot plate or wire and measuring the amount of current needed to maintain the hot surface at a specified temperature. In effect, the MAF works by measuring wind chill on the wire. Once the PCM knows the air temperature and it’s mass, it can more effectively calculate the proper air fuel mixture.

But what about humidity, doesn’t that have an effect on how the air cools the wire? You bet. That’s why the latest generation MAF sensors now include a humidity sensor. The new sensors calculate air flow, barometric pressure, intake air temperature, and humidity. GM is one company using the new sensors and have renamed it the Multifunction Intake Air sensor.

The new sensor has 8 wires.

Bosch and Hitachi supply some of the new sensors. As used on GM vehicles starting in 2012, these are the pinouts for the new sensors:

Hitachi sensor pinout:
Pin 1 – Signal, IAT 1
Pin 2 – +5V Reference
Pin 3 – Low Reference
Pin 4 – Signal, BARO (TIAP)
Pin 5 – Ignition, +12V
Pin 6 – Signal, MAF
Pin 7 – Ground, Chassis
Pin 8 – Signal, Humidity (duty cycle – %) and IAT 1 (frequency – Hz)

Bosch sensor pinout:
Pin 1 – Signal, Humidity (duty cycle – %) and IAT 1 (frequency – Hz)
Pin 2 – +5V Reference
Pin 3 – Signal, MAF
Pin 4 – Ground, Chassis
Pin 5 – Ignition, +12V
Pin 6 – Signal, BARO (TIAP)
Pin 7 – Low Reference
Pin 8 – Signal, IAT 1

Posted on by Rick Muscoplat

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