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. If the hot wire electronic sensing element must be replaced, then the entire assembly must be replaced. Replacing only the element may change the air flow calibration.
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.
Removal & Installation
- Before servicing the vehicle, refer to the Precautions section.
- Disconnect the battery ground cable.
- Disconnect the mass air flow (MAF) sensor electrical connector.
- Remove the 2 bolts and the MAF sensor.
To install, reverse the removal procedure. Tighten the bolts to 18 inch lbs. (2 Nm).
Before servicing the vehicle, refer to the Precautions section.
WARNINGUse only a high-impedance multimeter, otherwise damage to the PCM and/or sensors can result.
- Check the air inlet system (air cleaner, housing, ductwork) for obstructions or blockage.
- Check for broken/loose air outlet tube clamps (throttle body and air cleaner assembly ends), cracks/holes in the air outlet tube, and worn gaskets between the MAF sensor and the air cleaner assembly. Check throttle body bore for sludge. Verify the MAF sensor is connected. Repair as necessary.
- Disconnect the MAF harness connector.
With the key
, check the following:
Pins 2, 4, and 5 should be ground.
- Turn the key OFF and reconnect the MAF harness connector.
- Start the engine and backprobe pin 1. This voltage should change with the intake air temperature.
- Start the engine and backprobe pin 3. This voltage should rise with the engine rpm.