Circuit Description
The Mass Air Flow (MAF) sensor measures the amount of air ingested by the engine. The direct measurement of the air entering the engine is more accurate than calculating the airflow from the MAP, the IAT and the engine speed (speed/density). The MAF sensor has a battery feed, ground, and a signal circuit.
The MAF sensor used on this engine is a hot wire type. This engine uses the MAF sensor to measure air flow rate. The MAF output frequency is a function of the power required to keep the air flow sensing elements (hot wires) at a fixed temperature above the ambient temperature. Air flowing through the sensor cools the sensing elements. The amount of cooling is proportional to the amount of air flow. The MAF sensor requires a greater amount of current in order to maintain the hot wires at a constant temperature as the air flow increases. The MAF sensor converts the changes in current draw to a frequency signal read by the PCM. The PCM calculates the air flow (grams per second) based on this signal.
The PCM monitors the MAF sensor frequency. The PCM can determine if the sensor is stuck low, stuck high, not providing the airflow value expected for a given operating condition, or that the signal appears to be stuck based on a lack of signal variation expected during the normal operation. This diagnostic checks the range/performance of the MAF sensor. The MAF system performance or rationality diagnostic uses the MAP, the IAT, and the engine speed to calculate an expected airflow rate. The PCM then compares the rate to the actual measured airflow from the MAF sensor. This diagnostic checks for too high an airflow rate. When the PCM detects that the MAF sensor frequency is above a predetermined value, this DTC will set.
Conditions for Running the DTC
| • | The engine speed is at least 300 RPM. |
| • | The ignition voltage is at least 8.0 volts. |
| • | All conditions met for 1.0 second. |
Conditions for Setting the DTC
| • | The Mass Air Flow frequency is greater than 11,250 Hz. |
| • | All conditions met for greater than 1.0 second. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records. |
| • | The PCM utilizes speed density (RPM, MAP, IAT) for fuel management. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL and the DTC. |
Diagnostic Aids
Important: Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM\TAC modules.
If you cannot find a problem with the ignition feed circuit to the component, inspect the IGN mini relay for proper operation. Probe both sides of the ENG IGN 1 fuse with a test lamp connected to ground in order to determine if the IGN mini relay is suppling the power. Refer to Ignition Relay Diagnosis for further diagnosis of the IGN 1 mini relay.
Important: Water entering the air intake system that reaches the MAF sensor could cause this DTC to set. The water rapidly cools the hot wires in the sensor, causing a false indication of excessive airflow. Check the following areas for evidence (witness marks) of water intrusion:
| • | AIR system |
| • | Intake air system |
| • | The following may cause an intermittent: |
| - | Mis-routed harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| - | A poor connection in the ignition feed circuit to the MAF sensor can cause a DTC P0103 to set. |
| • | For an intermittent, refer to Symptoms . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Monitoring the MAF sensor frequency will determine if the fault is present or the malfunction is intermittent. A poor connection at the MAF sensor or at the fuse causes this DTC to set. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit will prevent any damage to the harness connector terminals.
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Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit prevents any damage to the harness connector terminals.
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This step checks for electro-magnetic interference on the MAF sensor signal circuit. There should be no signal indicated on the scan tool with the sensor disconnected.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||
Is the MAF sensor frequency above the specified value? | 11,250 Hz | |||||||
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Go to Diagnostic Aids | ||||||
Does scan tool indicate a MAF sensor frequency? | -- | |||||||
5 |
Did you find and correct the condition? | -- | ||||||
6 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Is the action complete? | -- | -- | |||||
7 |
Did you find and correct the condition? | -- | ||||||
8 |
Did you find and correct the condition? | -- | ||||||
9 |
Important:: Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement . Replace the PCM. Is the action complete? | -- | -- | |||||
10 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||
11 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table. | System OK |
