Crown Victoria, Grand Marquis, Town Car, 2006-2007

Mass Air Flow Sensor



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Fig. Diagram of air flow through throttle body, contacting MAF Sensor hot and cold wire (and IAT Sensor wire, where applicable) terminals.

The MAF sensor uses a hot wire sensing element to measure the amount of air entering the engine. Air passing over the hot wire causes it to cool. This hot wire is maintained at 200°C (392°F) above the ambient temperature as measured by a constant cold wire. The current required to maintain the temperature of the hot wire is proportional to the mass air flow. The MAF sensor then outputs an analog voltage signal to the PCM proportional to the intake air mass. The PCM calculates the required fuel injector pulse width in order to provide the desired air/fuel ratio. This input is also used in determining transmission electronic pressure control (EPC), shift and torque converter clutch scheduling.

The MAF sensor is located between the air cleaner and the throttle body or inside the air cleaner assembly. Most MAF sensors have integrated bypass technology with an integrated intake air temperature (IAT) sensor. The hot wire electronic sensing element must be replaced as an assembly. Replacing only the element may change the air flow calibration.

Removal & Installation

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  1. MAF sensor electrical connector
  3. MAF sensor retaining screw (2 required)
  5. MAF sensor
  7. Disconnect the battery ground cable.
  9. Disconnect the mass air flow (MAF) sensor electrical connector.
  11. Remove the MAF sensor retaining screws. To install, tighten to 53 inch lbs. (6 Nm).
  13. Remove the MAF sensor.
  15. To install, reverse the removal procedure.


MAF Sensor Pin Testing

For reference values, refer to PCM testing-PCM reference voltage chart

This pinpoint test is intended to diagnose the following:

Mass air flow sensor (12B579)
Harness circuits: MAF SIG, MAF RTN, vehicle power (VPWR), power ground (PWRGND), IAT and SIGRTN

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