Circuit Description
The mass air flow (MAF) sensor is an air flow meter. The control module supplies the MAF sensor a signal circuit. An ignition positive voltage circuit and a ground circuit are supplied to the MAF sensor by independent circuits. The MAF sensor heats a wire element, or grid, within the MAF sensor in order to maintain a calculated temperature. As inlet air flows across and cools the grid, the MAF sensor increases current flow to the grid in order to maintain the constant grid temperature. The MAF sensor converts the grid current flow into a frequency signal. The control module converts the MAF signal frequency into a grams per second value. During low air flow rates, such as at engine idle, the MAF sensor produces a low frequency signal. During high air flow rates, such as at wide open throttle-road load, the MAF sensor increases the frequency signal. The control module monitors the MAF sensor signal frequency in order to calculate the flow and mass of the air entering the engine.
This DTC is designed to detect an unusually high MAF sensor signal frequency. If the vehicle control module (VCM) detects a MAF signal frequency above the possible range of a normally operating MAF sensor, this DTC will be set.
Conditions for Running the DTC
| • | The engine is running |
| • | The engine speed is more than 300 RPM |
| • | The system voltage is more than 8 volts |
Conditions for Setting the DTC
The MAF frequency is 11000 Hz or more for more than 1 second
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles. |
| • | The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame/Failure Records. |
Conditions for Clearing the MIL or DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed. |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool in order to clear the DTCs. |
Diagnostic Aids
Check for the following conditions:
| • | A misrouted harness. Inspect the MAF sensor harness in order to ensure that the harness is not routed too close to the high voltage wires such as spark plug leads. |
| • | A damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving connectors and wiring harnesses related to the MAF sensor. A change in the display will indicate the location of the fault. |
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This step verifies that the problem is present at idle.
-
A frequency reading with the MAF sensor connector disconnected indicates an electromagnetic interference (EMI) related fault or a poor connection.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||
Is the MAF more than the specified value? | 20 g/s | |||||||
3 |
Does the scan tool indicate DTC P0103 Failed This Ignition? | -- | Go to Diagnostic Aids | |||||
Is the MAF equal to the specified value? | 0.0 g/s | |||||||
5 |
Did you find a problem? | -- | ||||||
6 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Is the action complete? | -- | -- | |||||
7 |
Did you find a problem? | -- | ||||||
8 |
Did you find a problem? | -- | ||||||
9 |
Important: The replacement VCM must be programmed. Replace the VCM. Refer to VCM Replacement/Programming . Is the action complete? | -- | -- | |||||
10 |
Does the scan tool indicate that the diagnostic Passed? | -- | ||||||
11 | Does the scan tool display any additional, undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK |
