DTC Descriptors
DTC P0102: Mass Air Flow (MAF) Sensor Circuit Low FrequencyDTC P0103: Mass Air Flow (MAF) Sensor Circuit High Frequency
Diagnostic Fault Information
Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
Ignition 1 Voltage | P0102 | P0101 | P0102 | -- | P0101, P0103 |
MAF Sensor Signal | P0102 | P0102 | P0102 | P0102 | P0101, P0103, P1101 |
Ground | -- | P0102 | P0102 | -- | P0102 |
Typical Scan Tool Data
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
Ignition 1 Voltage | -- | 0 Hz | 0 Hz | -- |
MAF Sensor Signal | 1,700-9,500 Hz | 0 Hz | 0 Hz | 0 Hz |
Ground | -- | -- | 0 Hz | -- |
Circuit/System 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 MAF/IAT sensor has the following circuits:
| • | An ignition 1 voltage circuit |
| • | A ground circuit |
| • | A MAF sensor signal circuit |
| • | An IAT sensor signal circuit |
| • | A low reference circuit |
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.
Conditions for Running the DTC
| • | The engine is running for more than one second. |
| • | The engine speed is more than 300 RPM. |
| • | The ignition 1 signal is more than 8 volts. |
| • | The above conditions are met for more than one second. |
| • | This DTC runs continuously within the enabling conditions. |
Conditions for Setting the DTC
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 11,000 Hz for more than 5 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Special Tools Required
J 38522 Variable Signal Generator
Circuit/System Verification
| • | Verify the integrity of the air induction system by inspecting for the following conditions: |
| - | Damaged components |
| - | Loose or improper installation |
| - | An air flow restriction |
| - | Any vacuum leak |
| - | Water intrusion |
| • | A wide open throttle (WOT) acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 2-6 g/s at idle to 100 g/s or more at the time of the 1-2 shift. |
| • | Verify that any electrical aftermarket devices are properly connected and grounded. Refer to Checking Aftermarket Accessories . |
Circuit/System Testing
P0102
- Inspect the fuse in the ignition 1 voltage circuit of the MAF sensor.
- Turn ON the ignition, with the engine OFF.
- Measure the battery voltage.
- Disconnect the MAF sensor.
- Connect a test lamp between the MAF sensor ignition 1 voltage circuit and a good ground.
- With the test lamp still connected, measure for battery voltage between the ignition 1 voltage circuit and a good ground.
- Measure for a proper range of 4.9-5.2 volts between the MAF sensor signal circuit and a good ground.
- Turn OFF the ignition and all electrical accessories. Allow sufficient time for all of the control modules to power down before taking a resistance measurement.
- Measure for a proper value of less than 5 ohms of resistance between the ground circuit of the MAF sensor and a good ground.
- Connect the J 38522 to the vehicle. Refer to Component Testing.
- Start the engine and observe the MAF Sensor parameter for a proper range of 4,950-5,025 Hz.
| ⇒ | If the fuse is open, test the spliced circuits and the components for a short to ground. |
| ⇒ | If the voltage is not within 1.5 volts of battery voltage, repair the high resistance or the open in the circuit. |
| ⇒ | If the voltage is within the proper range, test the circuit for a high resistance and for a short to any 5-volt circuit. |
| ⇒ | If the voltage is less than 4.9 volts, test the circuit for a short to ground, a high resistance, or an open. If the circuit tests normal, replace the ECM. |
| ⇒ | If the voltage is more than 5.2 volts, test the circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | If the resistance is more than 5 ohms, repair the high resistance or the open in the ground circuit. |
| ⇒ | 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. |
P0103
- Connect the J 38522 to the vehicle. Refer to Component Testing.
- Start the engine and observe the MAF Sensor parameter for a proper 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. |
Component Testing
To determine if the ECM can properly process the MAF sensor frequency signal, connect the J 38522 to the vehicle as follows:
- Turn OFF the ignition.
- Connect the battery voltage supply, and ground the black lead.
- Connect the red lead to the signal circuit of the MAF sensor.
- Set the Duty Cycle switch to Normal.
- Set the Frequency switch to 5 K.
- Set the Signal switch to 5 V.
- Start the engine.
- Observe the MAF Sensor parameter for the correct range of 4,950-5,025 Hz.
Repair Instructions
Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
