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 high load situation. The MAF sensor has an ignition 1 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. 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 Hz.

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 a misrouted harness. Verify that the MAF sensor harness is not routed too close to the following components:
- The secondary ignition wires or the coils
- The solenoids
- The relays
- The motors
^ A low minimum air rate may cause this DTC to set during deceleration. Inspect for the following conditions:
- A plugged intake air duct or dirty air filter element
- Objects blocking the MAF sensor air inlet screen
- Throttle bore and throttle plate coking
^ A Wide Open Throttle (WOT) acceleration from a stop should cause the MAF display on a scan tool to increase. This increase should be from about 6-12 g/s at idle to about 230 g/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 EGR valve flange and pipe
- The MAF sensor seal
- The MAP sensor seal
- The EVAP canister purge valve seal
- The fuel meter body seal
- The brake booster system
- The air induction system
- The crankcase ventilation system-Refer to Crankcase Ventilation System Inspection/Description in Engine. Testing and Inspection
^ If the problem is intermittent, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-10:

Steps 11-23:

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 reading 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-volt reference circuit.