P0102

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 frequency signal in order to provide the correct fuel delivery for a wide range of engine speeds and loads. A small quantity of air entering the engine indicates deceleration or idle. A large quantity of air entering the engine indicates an acceleration or a high load situation. The MAF sensor has an ignition positive voltage circuit, a ground circuit and a signal circuit. The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage in order to produce a frequency based on inlet air flow through the sensor bore. Diagnostic Trouble Code (DTC) P0102 will set if the PCM detects a frequency signal lower than the possible range of a normally operating MAF sensor.

CONDITIONS FOR RUNNING THE DTC
^ The engine is running.
^ The engine speed is greater than 300 RPM.
^ The ignition 1 signal is greater than 8 volts.

CONDITIONS FOR SETTING THE DTC
^ The MAF sensor frequency signal is less than 10 Hertz.
^ The condition exists for greater than 1.2 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.
^ Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS
Inspect for the following conditions:
^ A misrouted harness. Inspect the MAF sensor harness in order to ensure that the harness is not routed too closely to the following components:
- The secondary ignition wires or coils
- Any solenoids
- Any relays
- Any motors
^ A low minimum air rate may cause this DTC to set during deceleration. Inspect of the following conditions:
- A plugged intake air duct or a dirty air filter element
- Any objects blocking the air inlet screen of the MAF sensor
- Any throttle bore or throttle plate coking
^ A Wide Open Throttle (WOT) acceleration from a stop should cause the mass air flow display on a scan tool to increase from about 4-7 gm/s at idle to about 100 gm/s or more at the time of the 1-2 shift. If not, inspect for a restriction.
^ Any unmetered air entering the engine may cause this DTC to set. Inspect for vacuum leaks in the following components:
- The intake manifold
- The throttle body
- The Exhaust Gas Recirculator (EGR) valve flange and pipe
- The MAF sensor seal
- The Manifold Absolute Pressure (MAP) sensor seal
- The EVAP canister purge valve seal
- The EVAP canister purge valve seal
- The fuel meter body seal
- The brake booster system
- The air induction system
- The crankcase ventilation system

If the problem is intermittent, Refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-9:

Steps 10-20:

Steps 21-23:

The numbers below refer to the step numbers on the diagnostic table.
5. This step verifies the signal circuit from the MAF sensor electrical connector to the PCM. A voltage of less than 4 volts or more than 6 volts indicates a malfunction in the wiring or a poor connection.
6. This step tests the signal circuit of the MAF sensor for a short to another 5.0 volt reference circuit.