For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0102: Mass Air Flow (MAF) Sensor Circuit Low Frequency
DTC P0103: Mass Air Flow (MAF) Sensor Circuit High Frequency

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Ignition 1 Voltage | P0030, P0036, P0102, P0135, P0141, P0443, P0597, P0598 | P0101 | P0102 | -- | P0101, P0103
MAF Sensor Signal | P0102 | P0102 | P0102 | P0102 | P0068, P0101, P0103, P1101
Ground | -- | P0102 | P0102 | -- | --

### Typical Scan Tool Data

#### MAF Sensor

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine running at various operating conditions Parameter Normal Range: 1,700-2,100 Hz at idle
ignition Voltage | 0 Hz | 0 Hz | --
MAF Sensor Signal | 0 Hz | 0 Hz | 0 Hz
Ground | -- | 0 Hz | --

### Circuit Description

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 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.

### Conditions for Running the DTC

• | The engine is running for greater than one second.

• | The engine speed is greater than 300 RPM.

• | The ignition voltage is greater than 10 volts.

• | The DTCs run continuously when the above conditions are met for greater than 1 second.

### Conditions for Setting the DTC

#### P0102

The ECM detects that the MAF sensor signal is less than 900 Hz (0 g/s) for greater than 5 seconds.

#### P0103

The ECM detects that the MAF sensor signal is greater than 11,000 Hz (179 g/s) for greater than 5 seconds.

### Action Taken When the DTC Sets

DTCs P0102 and P0103 are Type B DTCs.

### Conditions for Clearing the MIL/DTC

DTCs P0102 and P0103 are Type B DTCs.

### Diagnostic Aids

• | Inspect the harness of the MAF sensor to verify that it is not routed too close to the following components:

- | The ignition coils

- | Any solenoids

- | Any relays

- | Any motors

• | Inspect for any contamination, water intrusion, or debris on the sensing elements of the MAF sensor. If debris is present, clean the sensor. If the sensor cannot be cleaned, replace the sensor.

• | A high resistance may cause a driveability concern before this DTC sets.

• | A MAF sensor that is installed incorrectly may set this DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

#### Special Tools

J 38522 Variable Signal Generator

### Circuit/System Verification

1. Engine idling, observe the DTC information with a scan tool. DTC P0102 or P0103 should not set.
2. Verify the scan tool MAF sensor Hz parameter is between 1,700-2,100 Hz.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that are captured in the Freeze Fame/Failure Records Data List.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
2. Ignition OFF, test for less than 5 Ω between the ground circuit terminal 2 and ground.

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

3. Ignition ON, load test for B+ between the ignition voltage circuit terminal 4 and ground.

⇒ | If less than the specified range, test the ignition voltage circuit for a short to ground or an open/high resistance.

4. Test for 4.8-5.2 V between the signal circuit terminal 5 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.

5. Ignition OFF, connect the red lead of the J 38522 to the signal circuit terminal 5 at the MAF/IAT sensor harness connector. Connect the battery voltage supply to B+, and ground the black lead.
6. Set the J 38522 to the following specifications:

• | Signal switch to 5 V

• | Frequency switch to 5K

• | Duty Cycle switch to Normal

Note: The engine will run rough and may stall.

7. Engine idling, observe the scan tool MAF Sensor Hz parameter. The scan tool MAF Sensor parameter should be between 4,950-5,025 Hz.

⇒ | If not within the specified range, replace the ECM.

8. If the circuits test normal, replace the MAF/IAT sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Mass Airflow Sensor with Intake Air Temperature Sensor Replacement

• | Control Module References for ECM replacement, setup, and programming