DTC P0102 Mass Air Flow (MAF) Sensor Circuit Low Frequency. Buick Century 1999

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1999 🢒 Century 🢒 Engine 🢒 Engine Controls - 3.1L 🢒 DTC P0102 Mass Air Flow (MAF) Sensor Circuit Low Frequency

Engine Controls Components
Cell 20: Engine Data Sensors-EGR, EVAP Purge, EVAP Vent and MAF
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Mass Air Flow (MAF) sensor measures the amount of air which passes through it into the engine during a given time. The PCM uses the mass air flow information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity of air indicates deceleration or idle.

The MAF sensor produces a frequency signal which can be monitored using a scan tool. The frequency will vary within a range of around 2000 Hertz at idle to near 8,000 Hertz at maximum engine load. DTC P0102 will be set if the signal from the MAF sensor is below the possible range of a normally operating MAF sensor.

Conditions for Running the DTC

•	The engine is running.

•	Ignition Voltage greater than 8.0V.

•	Throttle angle below 50%.

Conditions for Setting the DTC

•	MAF signal frequency is below 1200 Hertz.

•	Above conditions present for over 0.5 seconds.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

•

The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure.

•	The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

•	The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.

•	The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

•	The DTC can be cleared by using a scan tool.

Diagnostic Aids

Check for the following conditions:

Plugged intake air duct or filter element. A wide open throttle acceleration from a stop should cause the Mass Air Flow displayed on a scan tool to increase from about 4-6 gm/s at idle to 100 gm/s or greater at the time of the 1-2 shift. If not, check for a restriction.

Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

•	Poor terminal connection.

Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections Diagnosis , and Connector Repairs Wiring Systems.

•	Damaged harness.

Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems.

•	Inspect the PCM and the engine grounds for clean and secure connections.

If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set.

Test Description

The numbers below refer to the step numbers on the Diagnostic Table:

This step verifies that the problem is present at idle.

A voltage reading of less than 4.0 or over 6.0 volts at the MAF sensor signal circuit indicates a fault in the wiring or a poor connection.

Verifies that ignition feed voltage and a good ground are available at the MAF sensor.

This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

Step

Action

Value(s)

Yes

Was the Powertrain OBD System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Start the engine.
With the engine idling, monitor MAF FREQUENCY display on the scan tool engine data list.

Is MAF FREQUENCY below the specified value?

1200 Hz (1.2 kHz)

Go to Step 4

Go to Step 3

Turn the ignition on, and leave the engine off.
Review and record scan tool Fail Records data.
Operate vehicle within Fail Records conditions as noted.
Using a scan tool, monitor Specific DTC info for DTC P0102.

Does scan tool indicate DTC P0102 failed this ignition?

Go to Step 4

Go to Diagnostic Aids

Test for the following conditions:

•	Objects blocking the MAF sensor inlet screen.

•	Intake manifold vacuum leaks.

•	Vacuum leaks at throttle body.

•	Vacuum leaks at EGR valve flange and pipes.

•	Crankcase ventilation valve faulty, missing, or incorrectly installed.

If a problem is found, repair as necessary.

Was a problem found?

Go to Step 14

Go to Step 5

Turn the ignition off.
Disconnect the MAF sensor connector.
Turn the ignition on, and leave the engine off.
Using a J 39200 DMM, measure voltage between the MAF signal circuit and battery ground.

Is the voltage near the specified value?

5.0V

Go to Step 6

Go to Step 9

Connect a J 35616-200 test light between the MAF sensor ignition feed and ground circuits at the MAF sensor harness connector.

Is the J 35616-200 test light on?

Go to Step 8

Go to Step 7

Connect a J 35616-200 test light between MAF sensor ignition feed circuit and battery ground.

Is the J 35616-200 test light on?

Go to Step 10

Go to Step 11

Test for a poor connection at the MAF sensor.
If a poor connection is found, replace faulty terminal(s). Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector Repairs .

Was a poor connection found?

Go to Step 14

Go to Step 12

Test the MAF signal circuit between the PCM and the MAF sensor for an open, short to ground, short to the MAF ground circuit, or short to voltage.
If the MAF signal circuit is open or shorted, repair it as necessary. Refer to Wiring Repairs .

Was the MAF signal circuit open or shorted?

Go to Step 14

Go to Step 13

Locate and repair the open in the ground circuit to the MAF sensor. Refer to Wiring Repairs .

Is the action complete?

Go to Step 14

Locate and repair the open in the ignition feed circuit to the MAF sensor. Refer to Wiring Repairs .

Is the action complete?

Go to Step 14

Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement .

Is the action complete?

Go to Step 14