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 Hertz at idle to about 10,000 Hertz 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 greater than 2 counts.. |
| • | The ignition voltage is more than 8.0 volts. |
Conditions for Setting the DTC
| • | MAF signal frequency is below 1200 Hertz |
| • | 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:
| • | Poor connection at the PCM--Inspect harness connectors for: |
| • | Backed out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | Poor terminal to wire connection |
| • | Misrouted harness--Inspect the MAF sensor harness to ensure that it is not routed too close to high voltage wires such as spark plug leads. |
| • | 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. |
| • | Plugged intake air duct or filter element--A wide open throttle (WOT) 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 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 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.
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This step verifies that the problem is present at idle.
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A voltage reading of less than 4 or over 6 volts at the MAF sensor signal circuit indicates a malfunction in the wiring or a poor connection.
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Verifies that ignition feed voltage and a good ground are available at the MAF sensor.
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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.
7 Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||||
Does the scan tool indicate MAF Frequency less than the specified value? | 1200 Hz (1.2 kHz) | |||||||||||||
3 |
Does the scan tool indicate DTC P0102 failed this ignition? | -- | Go to Diagnostic Aids | |||||||||||
4 | Inspect for the following conditions:
Did you find and correct the condition? | -- | ||||||||||||
Does the voltage measure near the specified value? | 5 V | |||||||||||||
Connect a test lamp between the ignition feed circuit and the ground circuit of the MAF sensor. Does the test lamp illuminate? | -- | |||||||||||||
7 | Connect a test lamp between the ignition feed circuit of the MAF sensor and a good ground. Does the test lamp illuminate? | -- | ||||||||||||
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? | -- | ||||||||||||
9 | Test the signal circuit of the MAF sensor for an open, short to ground, or a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||||||
10 | Repair the open in the ground circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||||
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? | -- | -- | |||||||||||
12 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Did you complete the replacement? | -- | -- | |||||||||||
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 14 | |||||||||||
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||||||||||||
15 |
Does the DTC reset? | -- | System OK |
