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 provide an overview of each diagnostic category.

### DTC Descriptors

DTC P0100: Mass Air Flow (MAF) Sensor Circuit
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 | P0100 | P0100 | P0100 | -- | P0101
MAF Sensor Signal | P0100 | P0102 | P0100 | P0102 | P0101
Low Reference | -- | P0102 | P0100 | -- | P0101

### Circuit/System Description

The mass air flow (MAF) sensor is located in the air intake duct. The MAF sensor is an airflow meter that measures the amount of air that enters the engine. The MAF sensor uses a hot film that is cooled by air flowing past the sensing film as air enters the engine. The amount of cooling is proportional to the amount of the air flow. As the air flow increases, greater current is required in order to maintain the hot film at a constant temperature. The engine control module (ECM) uses the MAF sensor in order to provide the correct fuel delivery for all operating conditions.

### Conditions for Running the DTC

• | The engine is operating.

• | The ignition voltage is greater than 11 volts.

• | DTC P0100, P0102 and P0103 run continuously once the above conditions are met for 1 second.

### Conditions for Setting the DTC

#### P0100

• | The ECM detects that the MAF sensor signal is 0.0 Hz.

• | The condition exists for 4 seconds or for a cumulative of 50 seconds.

#### P0102

• | The ECM detects that the MAF sensor signal is less than 1,135 Hz.

• | The condition exists for 4 seconds or for a cumulative of 50 seconds.

#### P0103

• | The ECM detects that the MAF sensor signal is greater than 15,152 Hz.

• | The condition exists for 4 seconds or for a cumulative of 50 seconds.

### Action Taken When the DTC Sets

DTCs P0100, P0102, and P0103 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0100, P0102, and P0103 are Type B DTCs.

### Diagnostic Aids

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

- | The secondary ignition wires or coils

- | Any solenoids

- | Any relays

- | Any motors

• | Inspect the hydro-carbon (HC) filter in the air cleaner assembly for ruptures that would leak charcoal into the air intake, contaminating the sensing element.

• | 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.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Air Intake System Description

#### 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

### Circuit/System Verification

1. Engine idling for 1 minute. Observe the scan tool DTC information. DTCs P0100, P0102 and P0103 should not set.
2. 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 Frame/Failure Records Data List.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the MAF sensor.
2. Test for less than 5 ohms between the ground circuit terminal C and ground.

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

Caution: Do NOT use the low reference circuit in the component harness connector for this test. Damage to the control module may occur due to excessive current draw.

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

⇒ | If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all the components connected to the ignition circuit and replace as necessary.

4. Load test for 4.9-5.1 volts between the signal circuit terminal A and the ground circuit terminal C.

⇒ | If less than the specified range, test the signal circuit for an open/high resistance or a short to ground. 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. If all circuits test normal, replace the MAF sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Mass Airflow Sensor Replacement

• | Control Module References for engine control module replacement, setup, and programming