Circuit Description
The MAF sensor measures the amount of air which passes through the sensor in a given amount of time. The engine control module (ECM) uses this information to determine the operating requirements of the engine in order to control the fuel delivery. The ECM calculates the engine fuel requirements by monitoring the current flow on the signal wire from the MAF sensor. When the volume of air entering the MAF sensor increases, the current flow sensed by the ECM from the MAF sensor also increases. When the airflow decreases, the current sensed by the ECM also decreases.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0102 Mass Air Flow (MAF) Sensor Circuit Low Voltage
Conditions for Running the DTC
| • | The engine is running. |
| • | The engine speed is below 6,500 RPM. |
| • | DTC P0102 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects the MAF signal is less than 1.7 gs for more than 1 second.
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. |
Diagnostic Aids
Inspect for any of the following conditions:
| • | A mis-routed wiring harness -- Inspect the MAF sensor harness to ensure that the harness is not routed too close to high voltage or high amperage circuits. |
| • | A damaged wiring harness -- Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving the connectors and the wiring harnesses related to the MAF sensor. A change in the display will indicate the location of the fault. |
| • | Inspect for an air intake restriction. |
| • | An intermittent malfunction may be caused by a fault in the MAF sensor circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions . |
| • | If DTC P0102 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was first set. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View References: Engine Controls Connector End Views or Engine Control Module Connector End Views | ||||||||||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||||||||||||
2 |
Is the MAF sensor parameter less than the specified value? | 2.0 g/s | Go to Step 4 | Go to Step 3 | ||||||||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||||||||
4 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 5 | ||||||||||||||
Is the voltage within 0.5 volts of the specified value? | B+ | Go to Step 6 | Go to Step 10 | |||||||||||||||
6 |
Important: This procedure is using the 5 volt reference circuit of the MAP sensor to test the signal circuit of the MAF sensor. If DTC P0107 is set, refer to DTC P0107 , before proceeding with this test. Is the MAF Sensor parameter more than the specified value? | 4.98 V | Go to Step 8 | Go to Step 7 | ||||||||||||||
7 | Test the MAF sensor signal circuit for the following conditions:
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 | ||||||||||||||
8 | Test for shorted terminals and for an intermittent and for a poor connection at the MAF sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 | ||||||||||||||
9 | Test for shorted terminals and for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||||||||||||
10 |
Important: The engine 1 voltage circuit of the MAF sensor is spliced to other components of the vehicle. Repair the ignition 1 voltage circuit of the MAF sensor for the following conditions:
Did you complete the repair? | -- | Go to Step 13 | -- | ||||||||||||||
11 | Replace the MAF sensor. Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||||||||||
12 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||||||||||
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 | ||||||||||||||
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||||||||
