Circuit Description
The DTC P0101 Mass Air Flow (MAF) Sensor Performance diagnostic checks the accuracy of the mass air flow sensor signal. The MAF sensor measures the amount of air which passes through the sensor in a given amount of time. The powertrain control module (PCM) uses this information to determine the operating requirements of the engine in order to control the fuel delivery. The PCM calculates the engines fuel requirements by monitoring the current flow on the signal wire from the MAF sensor. When the volume of air entering the MAF sensor increases, the current flow sensed by the PCM from the MAF sensor also increases. When the air flow decreases, the current sensed by the PCM also decreases. The MAF sensor is an integral part of the throttle body assembly.
Conditions for Running the DTC
| • | DTC P0102, DTC P0103, DTC P0335, DTC P1408, DTC P1451 are not set. |
| • | The barometric pressure (BARO) is more than 75 kPa. |
| • | The intake air temperature is between than -14 to 70°C (7-158°F). |
| • | The engine speed is more than 2,000 RPM. |
| • | The throttle angle is less than 20 degrees. |
Conditions for Setting the DTC
| • | Maximum flow rate-- Minimum flow rate less than 0.1 g/sec. |
| • | The condition is present for at least 20 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active. |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer. |
Conditions for Clearing the MIL/DTC
| • | The MIL turns OFF after 3 consecutively passing cycles without a fault present. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | Perform the scan tool clear DTC information function in order to clear the DTC. |
Diagnostic Aids
Check for any of the following conditions:
| • | A skewed or malfunctioning manifold absolute pressure (MAP) sensor. A faulty MAP sensor or MAP sensor circuit can cause the PCM to incorrectly calculate the predicted mass air flow value. |
| • | A leak in the air inlet system or intake manifold. |
| • | A misrouted wiring harness. Inspect the MAF sensor harness to ensure that the harness is not routed too close to high voltage or high amperage circuits. |
| • | A damaged wiring harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving the connectors and the wiring harnesses related to the MAF sensor. A change in the display will indicate the location of the fault. |
| • | A plugged intake air duct or a dirty air filter element. |
If DTC P0101 is intermittent, driving the vehicle under the following conditions can verify whether the fault is present. Perform the scan tool clear DTC information function. Road test the vehicle while monitoring the DTC P0101 diagnostic on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0101 appears in the Not Ran Since Code Cleared list, the P0101 diagnostic has not yet run. When the DTC P0101 does not appear in the Not Ran Since Code Cleared list, the DTC P0101 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P0101 diagnostic has passed. DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.
An intermittent malfunction may be caused by a fault in the MAF sensor circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .
If DTC P0101 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was first set.
If any wiring repairs need to be made, refer to Wiring Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
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The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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This step verifies that the malfunction is present.
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This step checks that the ignition feed voltage is reaching the MAF sensor.
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This step checks that the mass air flow (MAF) sensor has a good ground.
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This step verifies that the MAF signal circuit is within range.
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Before replacing the MAF sensor check Diagnostic Aids above for any conditions that might apply.
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Before replacing the PCM check Diagnostic Aids above for any conditions that might apply.
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Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio. The DTC P0101 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0101 appears in the Not Ran Since Code Cleared list, the DTC P0101 diagnostic has not yet run. When the DTC P0101 does not appear in the Not Ran Since Code Cleared list, the DTC P0101 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P0101 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.
Step | Action | Value(s) | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||||
Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | ||||||||||||
2 |
Was a repair necessary? | -- | Go to Step 13 | Go to Step 3 | ||||||||||
Is DTC P0101 set? | -- | Go to Step 4 | Go to Diagnostic Aids | |||||||||||
Is the test lamp illuminated? | -- | Go to Step 5 | Go to Step 9 | |||||||||||
Connect the test lamp between the MAF sensor ignition feed circuit and the ground circuit at the MAF sensor harness connector. Is the test lamp illuminated? | -- | Go to Step 6 | Go to Step 10 | |||||||||||
Is the voltage within the specified range? | 1.5-1.8 V | Go to Step 7 | Go to Step 8 | |||||||||||
7 |
Was a repair necessary? | -- | Go to Step 13 | Go to Step 12 | ||||||||||
8 |
Was a repair necessary? | -- | Go to Step 13 | Go to Step 11 | ||||||||||
9 | Locate and repair the open circuit in the ignition feed circuit to the MAF sensor. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 13 | -- | ||||||||||
10 | Locate and repair the open circuit in the ground circuit to the MAF sensor. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 13 | -- | ||||||||||
Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Is the action complete? | -- | Go to Step 13 | -- | |||||||||||
Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 13 | -- | |||||||||||
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 | |||||||||||
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||||
