Circuit Description
The mass air flow (MAF) sensor measures the amount of air which passes through the sensor into the engine during a given time. The PCM uses the MAF information in order to monitor the 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 approximately 2,000 Hertz at idle to approximately 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. |
| • | TP angle is less than 50 percent. |
| • | System voltage is more than 9 volts. |
Conditions for Setting the DTC
| • | The MAF signal frequency is less than 1200 Hertz. |
| • | The above conditions are present for longer than 0.5 seconds +400 3X reference periods, or 133 crankshaft revolutions. |
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 the idle air control valve position, the throttle position, the RPM and the barometric pressure. |
| • | The PCM will store the conditions which were present when the DTC set as Freeze Frame and the Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF 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 Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
| • | Inspect for the following conditions: |
| - | A poor connection at the PCM |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal to wire connection--Use a corresponding mating terminal to check for proper terminal tension. |
| - | A mis-routed harness--Inspect the MAF sensor harness to ensure that the sensor is not routed too close to high voltage wires such as spark plug leads. |
| - | Damaged harness--If the harness appears to be OK, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the malfunction. Refer to Wiring Repairs . |
| - | 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 approximately 4-7 gm/s at idle to 100 gm/s or more at the time of the 1-2 shift. If this does not occur, check for a restriction. |
| • | If DTC P0102 cannot be duplicated, the information included in the Fail 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:
-
This step verifies that the problem is present at idle.
-
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.
-
This step verifies that the 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 | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||||
Does the scan tool indicate a 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 |
Did you find and correct the condition? | -- | ||||||||||||
Does the voltage measure near the specified value? | 5 V | |||||||||||||
Connect a DMM between the ignition feed circuit of the MAF sensor and a known good ground. Does the voltage measure equal to the specified value? | Battery Positive Voltage | |||||||||||||
7 | Test the ground circuit for the MAF sensor for an open or high resistance and repair the sensor if necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||||||||||||
8 |
Did you find and correct the condition? | -- | ||||||||||||
9 | Repair the open or high resistance in the ignition feed circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||||
10 | 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? | -- | ||||||||||||
11 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Did you complete the replacement? | -- | -- | |||||||||||
12 |
Did you find and correct the condition? | -- | ||||||||||||
|
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||||||||||||
14 |
Does the DTC reset? | -- | System OK |
