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 Sensor Voltage LowDTC P0103: Mass Air Flow Sensor Voltage High
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
Ignition 1 Voltage | P0102 | P0101, P0102 | 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. |
| • | These DTC's run continuously within the enabling conditions. |
Conditions for Setting the DTC
P0102
The ECM detects that the MAF Sensor parameter is less than 1,867 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.
Action Taken when the DTC Sets
DTCs P0102 or P0103 are type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0102 or P0103 are type B DTCs.
Diagnostic Aids
| • | Verify the integrity of the air induction system by inspecting for the following conditions: |
| - | A restricted or collapsed air intake duct. |
| - | A misaligned air intake duct. |
| - | A dirty or deteriorating air filter element. |
| - | Any objects blocking the air inlet screen of the MAF/IAT sensor. |
| - | Any water intrusion in the induction system. |
| - | Any contamination or debris on the sensing elements of the MAF sensor. |
| - | Damaged components. |
| - | Loose or incorrect installation. |
| - | Any air flow restriction. |
| - | Any vacuum leak. |
| • | 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 . |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Special Tools Required
Commercially available variable Signal Generator
Circuit/System Testing
P0102
- Inspect the fuse in the ignition 1 voltage circuit of the MAF sensor.
- Ignition ON, engine OFF.
- Measure the battery voltage.
- Disconnect the MAF sensor.
- Connect a test lamp between the MAF sensor ignition 1 voltage circuit and a known ground.
- With the test lamp still connected, measure for battery voltage between the ignition 1 voltage circuit and a known ground.
- Measure for a proper range of 4.9-5.2 volts between the MAF sensor signal circuit and a known ground.
- Ignition OFF and all electrical accessories OFF. 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 3 ohms of resistance between the ground circuit of the MAF sensor and a known ground.
- Connect the Signal Generator 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. |
Important: Certain resistances will not be detectable if a test lamp is not connected to provide a circuit load.
| ⇒ | If the voltage is not within 0.5 volts of battery voltage, test the circuit short to ground or an open/high resistance. |
Important: The voltage will still be within the proper range with certain high resistances and with a short to a 5 volt circuit.
| ⇒ | If the voltage is within the proper range, test the circuit for a high resistance, a short to the IAT signal circuit, 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, open/high resistances. 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 3 ohms, repair the open/high resistance 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 Signal Generator 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 Signal Generator to the vehicle as follows:
- Ignition OFF.
- Connect the battery voltage supply and connect the earth lead to a known ground.
- 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
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Engine Control Module Replacement for engine control module replacement, setup and programming. |
