The mass air flow (MAF) sensor is integrated with the intake air temperature (IAT) sensor. The MAF sensor is an air flow meter that measures the amount of air entering the engine. The engine control module (ECM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition. The MAF/IAT sensor has the following circuits:

The ECM applies 5 volts to the MAF sensor on the MAF sensor signal circuit. The sensor uses the voltage to produce a frequency based on the inlet air flow through the sensor bore. The frequency varies within a range of near 1,700 Hertz at idle to near 9,500 Hertz at maximum engine load.

P0102

The ECM detects that the MAF Sensor parameter is less than 10 Hz for more than 5 seconds.

P0103

The ECM detects that the MAF Sensor parameter is more than 14,500 Hz for more than 5 seconds.

DTCs P0102 and P0103 are Type B DTCs.

DTCs P0102 and P0103 are Type B DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Special Tools Required

J 38522 Variable Signal Generator

1. Verify the integrity of the entire air induction system by inspecting for the following conditions:

•	Damaged components

•	Loose or improper installation

•	An air flow restriction

•	Any vacuum leak

•	Water intrusion

2. Engine running, observe the DTC information with a scan tool. DTCs P0102 or P0103 should not set.
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
2. Ignition OFF, allow at least 60 seconds for the control module to power down.
3. Test for less than 5 ohms of resistance between the ground circuit terminal C and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal B and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

5. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal A and ground.

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

6. Connect the J 38522 to the vehicle. Refer to Component Testing for instructions.

To determine if the ECM can properly process the MAF sensor frequency signal, connect the J 38522 to the vehicle as follows:

1. Ignition OFF, connect the battery voltage supply and ground the black lead.
2. Connect the red lead to the signal circuit of the MAF sensor.
3. Set the Duty Cycle switch to Normal.
4. Set the Frequency switch to 5 K.
5. Set the Signal switch to 5 V.
6. Engine running, observe the MAF Sensor parameter for the correct range of 4,950-5,025 Hz.

⇒	If the MAF Sensor parameter is not within the specified range, replace the ECM.

⇒	If the MAF Sensor parameter is within the specified range, replace the MAF sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.