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 to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition. The MAF sensor has the following circuits:
• | An ignition 1 voltage circuit |
• | A ground circuit |
• | A signal circuit |
The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage to produce a frequency based on the inlet air flow through the sensor bore. The frequency varies within a range of near 2,000 Hertz at idle to near 10,000 Hertz at maximum engine load. If the PCM detects the frequency signal is less than the possible range of a correctly operating MAF sensor DTC P0102 sets.
• | The engine is running for more than 2 seconds. |
• | The engine speed is more than 400 RPM. |
• | The ignition 1 signal is more than 8 volts. |
• | The MAF sensor frequency is stable for more than 1 second. |
The PCM detects that the MAF sensor frequency signal is less than 1,200 Hz for more than 0.6 second.
• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
• | Clear the MIL and the DTC with a scan tool. |
• | Inspect the harness of the MAF sensor to verify that it is not routed too close to the following components: |
- | The secondary ignition wires or coils |
- | Any solenoids |
- | Any relays |
- | Any motors |
• | A low minimum air rate through the sensor bore at idle or during deceleration may cause this DTC to set. Inspect for any vacuum leak downstream of the MAF sensor. |
• | Inspect for any contamination or debris on the sensing elements of the MAF sensor. |
• | A wide open throttle acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 3-10 g/s at idle to 170 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system. |
• | A high resistance of 15 ohms or more on the ground circuit of the MAF sensor may cause this DTC to set. A high resistance may cause a driveability concern before this DTC sets. |
• | A high resistance of 15 ohms or more on the ignition 1 voltage circuit can cause this DTC to set. A high resistance may cause a driveability concern before this DTC sets. |
• | If the condition is intermittent, refer to Intermittent Conditions . |
The numbers below refer to the step numbers on the diagnostic table.
This step will determine if any mechanical faults have caused this DTC to set.
This voltage drop test will determine if high resistance has caused this DTC to set.
This step verifies the voltage signal from the PCM to the MAF sensor connector.
This step tests the signal circuit of the MAF sensor for a short to another 5-volt reference circuit.
This step will determine if the PCM is able to process the frequency signal that it receives from the MAF sensor.
This step will determine which portion of the circuit or which component is shorted to ground.
This step verifies that the signal circuit is not shorted to any other PCM circuit.
Step | Action | Values | Yes | No | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||
2 |
Is the MAF Sensor parameter less than the specified value? | 1,200 Hz | Go to Step 4 | Go to Step 3 | ||||||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||||||
4 |
Does the movement of the harness or the connector affect the MAF Sensor parameter? | -- | Go to Step 20 | Go to Step 5 | ||||||||||||
Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 6 | |||||||||||||
6 | Inspect the fuse in the ignition 1 voltage circuit of the MAF sensor. Is the fuse open? | -- | Go to Step 14 | Go to Step 7 | ||||||||||||
Is the voltage within 0.50 volts of the specified value? | B+ | Go to Step 8 | Go to Step 21 | |||||||||||||
8 |
Important: All electrical components and accessories must be turned OFF.
Is the resistance less than the specified value? | 5 ohms | Go to Step 9 | Go to Step 22 | ||||||||||||
Is the voltage within the specified range? | 4.8-5.2 V | Go to Step 10 | Go to Step 13 | |||||||||||||
Do any additional DTCs set? | -- | Go to Step 24 | Go to Step 11 | |||||||||||||
Is the MAF Sensor parameter within the specified range? | 4,950-5,025 Hz | Go to Step 12 | Go to Step 15 | |||||||||||||
12 |
Important: An abnormal resistance on the signal circuit will disable the MAF sensor frequency before the voltage starts to drop out of the correct parameter of 4.8-5.2 volts. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 18 | ||||||||||||
13 | Is the voltage less than the specified value? | 4.8 V | Go to Step 15 | Go to Step 16 | ||||||||||||
Important:: The ignition 1 voltage circuit of the MAF sensor is spliced to other components of the vehicle. Test the ignition 1 voltage circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | -- | |||||||||||||
15 |
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 28 | Go to Step 17 | ||||||||||||
16 |
Important:: Disconnecting the PCM connectors may eliminate the short to voltage if the signal circuit is shorted to another PCM circuit.
Is the voltage more than the specified value? | 0 V | Go to Step 23 | Go to Step 17 | ||||||||||||
Measure the resistance from the signal circuit of the MAF sensor to all other circuits at both PCM connectors with a DMM. Refer to Circuit Testing in Wiring Systems. Is the resistance less than the specified value? | ∞ ohms | Go to Step 25 | Go to Step 19 | |||||||||||||
18 | Test for an intermittent and 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 28 | Go to Step 26 | ||||||||||||
19 | Test for an intermittent and for a poor connection 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 28 | Go to Step 27 | ||||||||||||
20 | Repair the wiring or the connector as needed. Refer to Wiring Repairs and Connector Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 28 | -- | ||||||||||||
21 | Repair the high resistance or the open in the MAF sensor ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 28 | -- | ||||||||||||
22 | Repair the high resistance or the open in the MAF sensor ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 28 | -- | ||||||||||||
23 | Repair the short to voltage in the MAF sensor signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 28 | -- | ||||||||||||
24 | Repair the short between the MAF sensor signal circuit and the 5-volt reference circuit for which the DTC set. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 28 | -- | ||||||||||||
25 | Repair the circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 28 | -- | ||||||||||||
26 | Replace the MAF/IAT sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 28 | -- | ||||||||||||
27 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 28 | -- | ||||||||||||
28 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 29 | ||||||||||||
29 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK |