Circuit Description
The mass air flow (MAF) sensor measures the amount of air which passes through it into the engine during a given time. The powertrain control module (PCM) uses the MAF sensor information to monitor the engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle.
The MAF sensor produces a frequency signal which can be monitored by using a scan tool. The frequency will vary within a range of around 2000 Hz at idle to near 8,000 Hz at the maximum engine load. DTC P0103 will be set if the signal from the MAF sensor is more than the possible range of a normally operating MAF sensor.
Conditions for Running the DTC
| • | The engine is running. |
| • | The ignition voltage is more than 8.0 volts. |
| • | The IAC is more than 2 counts. |
Conditions for Setting the DTC
| • | The MAF signal frequency is more than 11,500 Hz (11.5 kHz). |
| • | The conditions are present for 12 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecuitive trip in which the diagnostic has been run and failed. |
| • | If equipped with traction control, the PCM will command the EBTCM via the serial data circuit to turn OFF traction control, and the EBTCM will illuminate the TRACTION OFF lamp. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool. |
Diagnostic Aids
Inspect for the following conditions:
| • | A poor connection at the PCM. Inspect the harness connectors for the following conditions: |
| - | Backed-out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal-to-wire connection |
| • | A misrouted harness. Inspect the MAF sensor harness to ensure that the harness is not routed too closely to high voltage wires such as the 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 the connectors and the wiring harnesses related to the MAF sensor A change in the display will indicate the location of the fault. |
Refer to Testing for Continuity , Testing for Intermittent Conditions and Poor Connections , Repairing Connector Terminals and Connector Repairs in Wiring Systems.
If DTC P0103 cannot be duplicated, the information included in the Failure Records data can be useful in determining vehicle mileage since the DTC was last set.
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 malfunction or a poor connection.
-
This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). If the PCM is replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Is the MAF Frequency more than the specified value? | 11,500 Hz 10,500 Hz | |||
3 |
Does the scan tool indicate DTC P0103 failed this ignition? | -- | Go to Diagnostic Aids | |
Does the MAF Frequency equal the specified value? | 0 Hz | |||
5 | Inspect 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? | -- | ||
6 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Did you complete the replacement? | -- | -- | |
7 | Inspect the MAF sensor harness for incorrect routing at the following locations:
Did you find and correct the condition? | -- | ||
8 | Inspect for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||
10 |
Does the DTC reset? | -- | System OK |
