DTC P0102 Mass Air Flow (MAF) Sensor Circuit Low Frequency. Buick GL7 (Export) 2000

For 1990-2009 cars

### Circuit Description

The mass air flow (MAF) sensor measures the amount of air which passes through it into the engine. 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 Hz at idle to about 10,000 Hz at maximum engine load. DTC P0102 will be set if the signal frequency from the MAF sensor is lower than the possible range of a normally operating MAF sensor.

### Conditions for Running the DTC

• | The engine is running.

• | The IAC is more than 2 counts.

• | The ignition voltage is more than 8.0 volts.

### Conditions for Setting the DTC

• | The MAF signal frequency is less than 1200 Hz.

• | The above conditions are present for over 0.5 seconds

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) the first time the malfunction is detected.

• | The PCM calculates an airflow value based on idle air control valve position, throttle position, RPM and barometric pressure.

• | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been 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 the scan tool.

### Diagnostic Aids

Inspect for the following conditions:

• | A poor connection at the PCM. Inspect the harness connectors for:

- | Backed-out terminals

- | Improper mating

- | Broken locks

- | Improperly formed or damaged terminals

- | Poor terminal-to-wire connection

• | A misrouted harness. Inspect the MAF sensor harness to ensure that the harness is not routed too close to high voltage wires such as the spark plug leads.

• | A damaged harness. Inspect the wiring harness for damage.

• | If the harness appears to be OK, observe the scan tool while moving connectors and wiring harnesses related to the MAF sensor. A change in the display will indicate the location of the malfunction.

• | A plugged intake air duct or filter element. A wide open throttle (WOT) acceleration from a stop should cause the MAF displayed on a scan tool to increase from about 4-6 gm/s at idle to 100 gm/s or more at the time of the 1-2 shift. If not, check for a restriction.

If DTC P0102 cannot be duplicated, the information included in the Failure Records data can be useful in determining the vehicle mileage since the DTC was last set. This may assist in diagnosing the condition.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step verifies that the problem is present at idle.

2. A voltage reading of less than 4 volts or more than 6 volts at the MAF sensor signal circuit indicates a malfunction in the wiring or a poor connection.

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

4. This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). If the PCM is replaced, the new PCM must be programmed.

#### DTC P0102 - MAF Sensor Circuit Low Frequency

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check

2

1. Start the engine.
2. With a scan tool, observe the MAF Frequency parameter.

Is the MAF Frequency less than the specified value?

1200 Hz

Go to Step 4

Go to Step 3

3

1. Turn ON the ignition.
2. With a scan tool, observe and record the scan tool Failure Records data.
3. Operate the vehicle within the Failure Records conditions.
4. With a scan tool, observe the Specific DTC info for DTC P0102.

Does the scan tool indicate DTC P0102 failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

Inspect for the following conditions:

• | Any objects blocking the MAF sensor inlet screen

• | Any vacuum leaks around the intake manifold

• | Any vacuum leaks at throttle body

• | Any vacuum leaks at the EGR valve flange and pipes

• | A malfunctioning, missing, or incorrectly installed crankcase ventilation valve

Did you find and correct the condition?

--

Go to Step 15

Go to Step 5

5

1. Turn OFF the ignition.
2. Disconnect the MAF sensor.
3. Turn ON the ignition, leaving the engine OFF.
4. Connect a DMM between the signal circuit of the MAF sensor and ground.

Is the voltage near the specified value?

5 V

Go to Step 6

Go to Step 9

6 | Connect a test lamp between the ignition feed circuit and the ground circuit of the MAF sensor. Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 7
7 | Connect a test lamp between the ignition feed circuit of the MAF sensor and ground. Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 11
8 | Inspect for a poor connection at the MAF sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12

9

• | Test the signal circuit of the MAF sensor for a short to 5 volt.

• | Test the signal circuit of the MAF sensor for an open, a short to ground, or a short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

10 | Repair the open in the ground circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | --
11 | Repair the open in the ignition feed circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | --
12 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Did you complete the replacement? | -- | Go to Step 15 | --
13 | Inspect for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14
14 | Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 15 | --

15

1. Use the scan tool in order to record the Failure Records and clear the DTCs.
2. Operate the vehicle within the Failure Records conditions as noted.

Does the DTC reset?

--

Go to Step 2

System OK