P0102

DTC P0102

CIRCUIT DESCRIPTION
The mass air flow (MAF) sensor is an air flow meter that measures the amount of air that enters the engine. It is fitted between the air cleaner and turbocharger. A small quantity of air that enters the engine indicates deceleration or idle. A large quantity of air that enters the engine indicates acceleration or a high load condition. The MAF sensor has the following circuits.
- Ignition voltage circuit
- Low reference circuit
- MAF sensor signal circuit

The engine control module (ECM) monitors the MAF sensor signal for voltage outside the normal range of the MAF sensor. If the ECM detects an excessively low MAF sensor signal voltage, this DTC will set.

Condition for Running the DTC
- DTCs P0103, P0642 and P0643 are not set.
- The battery voltage is more than 10 volts.
- The ignition switch is ON.
- The engine speed is higher than 600 RPM.
- The engine run time is longer than 30 seconds.

Condition for Setting the DTC
- The ECM detects that the MAF sensor signal voltage is less than 0.08 volts for longer than 7 seconds.

Action Taken When the DTC Sets
- The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Freeze Frame/Failure Records.
- The ECM limits fuel injection quantity within 70%.
- The ECM closes the EGR valve and holds to close position.

Condition for Clearing the MIL/DTC
- The ECM turns OFF the MIL after 3 consecutive driving cycles when the diagnostic runs and does not fail. (12,000 lbs GVW)
- The ECM turns OFF the MIL when the diagnostic runs and does not fail. (Except 12,000 lbs GVW)
- 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 after the ECM turns OFF the MIL.
- Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
If an intermittent condition is suspected, the following may cause an intermittent:
- Poor connections
- Misrouted harness
- Rubbed through wire insulation
- Broken wire inside the insulation

Check for the following conditions:
- Poor connection at the ECM: Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- Damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, observe the "MAF Sensor" display on the scan tool with the engine running while moving connectors and the wiring harness related to the sensor. A change in the display will indicate the location of the fault.

DTC P0102
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Engine Control Module (ECM) Connector End Views

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