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 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 2,000 Hertz at idle to about 10,000 Hertz at 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 is cranking for 0.5 second or running for 1 second.
^ The engine speed is at least 50 RPM.
^ The Ignition 1 signal is greater than 8 volts.
^ The IAC position is greater than 5 counts.
^ All of the above conditions are present for greater than 1 second.

CONDITIONS FOR SETTING THE DTC
^ The MAF sensor frequency signal is less than 1,200 Hz.
^ The above condition is present for greater than 12 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ First failure:
- The MIL is not turned ON.
- A DTC is stored in memory under Failed Last Test.
- The Failure Records are stored
^ Second consecutive drive cycle with a failure:
- The MIL is turned ON.
- A DTC is stored in memory under history.
- The Freeze Frame data is stored.
- The Failure Records are stored.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after the third consecutive trip the diagnostic has run and passed.
^ The history DTC will clear if the fault conditions have not been detected for 40 warm-up cycles.
^ A scan tool can be used to clear DTC information.

DIAGNOSTIC AIDS
Inspect for the following conditions:
^ A misrouted harness. Inspect the harness of the MAF sensor in order to ensure that it is not routed too close to the following:
- 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 for the following conditions:
- A plugged or collapsed intake air duct or dirty air filter element
- Objects blocking the air inlet screen of the MAF sensor
- 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 from about 4-7 g/s at idle to about 130 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 anywhere downstream of the MAF sensor.

If you suspect the vehicle condition 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 1-9:

Steps 10-21:

Steps 22-23:

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 greater 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.