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. The frequency will vary within a range of around 2000 Hz at idle to about 10,500 Hz at the maximum engine load. 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 speed is more than 250 RPM.
^ The ignition 1 signal is more than 8 volts.
^ The engine run time is more than 1 second.

CONDITIONS FOR SETTING THE DTC
^ The MAF sensor frequency signal is less than 1,200 Hz.
^ The condition is present for at least 2 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic has been run and failed.
^ The PCM stores the conditions present when the DTC set as Freeze Frame/Failure Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns the MIL off after the third consecutive trip in which the diagnostic has been run and passed.
^ The history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.
^ Use the scan tool in order to clear the DTCs.

DIAGNOSTIC AIDS
Inspect for the following conditions:
^ A misrouted harness. Inspect the MAF sensor harness in order to ensure that the harness is no routed too closely to the following components:
- The ignition cassette
- Any solenoids
- Any relays
- Any 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 a dirty air filter element
- Any objects blocking the air inlet screen of the MAF sensor
- Any coking in the throttle bore and on the throttle plate
^ A Wide Open Throttle (WOT) acceleration from a stop should cause the MAF 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 anywhere downstream of the MAF sensor.

If you suspect the vehicle problem may be related to aftermarket accessories, refer to Checking Aftermarket Accessories in Diagrams. Service Precautions

If the problem is intermittent refer to intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-2:

Steps 3-11:

Steps 12-23:

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 5.0-volt reference circuit.