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 P0102: Mass Air Flow (MAF) Sensor Circuit Low FrequencyDTC 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 | 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 | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Ignition 1 Voltage | 0 Hz | 0 Hz | -- |
MAF Sensor Signal | 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 ignition 1 signal is more than 8 volts. |
| • | The above conditions are met for more than one second. |
| • | These DTCs run continuously when the above conditions are met. |
Conditions for Setting the DTC
P0102
The ECM detects that the MAF Sensor parameter is less than 1,400 Hz for greater than 5 seconds.
P0103
The ECM detects that the MAF Sensor parameter is more than 14,500 Hz 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
| • | 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 improper 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
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
| • | Engine running, observe the scan tool MAF Sensor parameter. The reading should be between 1,700-3,800 Hz depending on the engine coolant temperature (ECT). |
| • | 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 greater than 180 g/s at the time of the 1-2 shift. |
| • | 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. |
Circuit/System Testing
Important: All electrical components and accessories must be turned OFF and allowed to power down.
- Verify the integrity of the air induction system by inspecting for the following conditions:
- Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
- Ignition OFF for 90 seconds, test for less than 5 ohms between the ground circuit terminal C and ground.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal B and ground.
- Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal A and ground.
- Ignition OFF, connect the red lead of the J 38522 to the signal circuit terminal A at the MAF/IAT sensor harness connector. Connect the battery voltage supply to B+. Connect the black lead to ground.
- Set the J 38522 signal to 5 volts, the Frequency to 5K, and the Duty Cycle to Normal.
- Engine idling, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 4,950-5,025 Hz.
- If all other circuits test normal, replace the MAF sensor.
| • | Loose or improper installation |
| • | Water intrusion |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. |
| ⇒ | If less than the specified range, test the signal circuit terminal A 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. |
| ⇒ | If the MAF Sensor parameter is not within the specified range, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
