Circuit Description
The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The powertrain control module (PCM) 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 sensor has the following circuits:
| • | An ignition 1 voltage circuit |
| • | A ground circuit |
| • | A signal circuit |
The PCM applies a voltage to the sensor on the 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 2,500 Hertz at idle to near 10,000 Hertz at maximum engine load. If the PCM detects a frequency signal that is more than the possible range of a correctly operating MAF sensor DTC P0103 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0103 Mass Air Flow (MAF) Sensor Circuit High Frequency
Conditions for Running the DTC
| • | The engine is running for more than 30 seconds. |
| • | The engine speed is more than 500 RPM. |
| • | The ignition 1 signal is more than 11 volts. |
| • | The above conditions are met for more than 2.5 seconds. |
Conditions for Setting the DTC
The PCM detects that the MAF sensor frequency signal is more than 11,000 Hertz for more than 3 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. |
Diagnostic Aids
| • | Inspect the Air Induction System for any water intrusion. The water rapidly cools the hot sensing elements in the sensor causing a false indication of excessive air flow. Any water that reaches the MAF sensor will skew the sensor and may cause this DTC to set. |
| • | A poor connection at the fuse for the ignition 1 voltage circuit of the MAF sensor may cause this DTC to set. |
| • | If the condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for electromagnetic interference (EMI) on the signal circuit of the MAF sensor. A frequency reading with the MAF sensor disconnected may indicate an EMI related fault or a poor connection at the PCM. Disconnecting the MAF sensor may set additional related DTCs.
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This step will determine if incorrect harness routing has caused this DTC to set.
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This step will determine if water intrusion has caused this DTC to set.
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This step will determine if high resistance at any point in the ignition 1 voltage circuit has caused this DTC to set.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||||
2 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||||||
Is the MAF sensor parameter more than the specified value? | 0 Hz | Go to Step 4 | Go to Step 5 | |||||||||
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 | |||||||||
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 6 | |||||||||
Test the ignition 1 voltage circuit of the MAF sensor for the following conditions:
Refer to Circuit Testing , Testing for Intermittent Conditions and Poor Connections , Wiring Repairs , and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 | |||||||||
7 | Test 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 11 | Go to Step 9 | ||||||||
8 | Test for an intermittent and for a poor connection at the powertrain control module (PCM). 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 11 | Go to Step 10 | ||||||||
9 | Replace the MAF/IAT sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- | ||||||||
10 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 11 | -- | ||||||||
11 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 12 | ||||||||
12 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | ||||||||
