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P0101



DTC P0101

DTC DESCRIPTOR

DTC P0101
DTC P0101 Mass Air Flow (MAF) Sensor Performance

DIAGNOSTIC FAULT INFORMATION






IMPORTANT:
- Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- If there are any other DTCs set, diagnose those first.

TYPICAL SCAN TOOL DATA

MAF Sensor:






CIRCUIT/SYSTEM DESCRIPTION
The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The engine control module (ECM) uses the MAF sensor voltage signal to provide the correct fuel delivery for a reduction in emissions. The ECM uses the MAF sensor signal to control fuel delivery until a calibrated amount of engine air flow is attained. The MAF sensor produces an output voltage based on the inlet air flow through the air induction system. This output voltage will display on the scan tool as a voltage parameter and as a grams per second (g/s) parameter. The ECM compares the actual MAF sensor voltage signal to a predicted MAF value. This comparison will determine if the signal is stuck, or is too low or too high for a given operating condition.

CONDITIONS FOR RUNNING THE DTC
- DTC P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0642, P0643, P0652, P0698, P0699, P2228, P2229 are not set.
- The ignition 1 signal is between 9-18 volts.
- The intake air temperature (IAT) Sensor parameter is more than -20°C (-4°F).
- The engine coolant temperature (ECT) Sensor parameter is more than -20°C (-4°F).
- The BARO Sensor parameter is more than 71 kPa.
- The engine speed is less than 3,500 RPM.
- The engine speed is steady within a range of 50 RPM.
- The above conditions are met for more than 2 seconds
- This DTC runs continuously within the enabling conditions.

CONDITIONS FOR SETTING THE DTC
The ECM detects that the MAF sensor voltage signal is not within a predetermined range of the calculated MAF value for more than 15 seconds.

ACTION TAKEN WHEN THE DTC SETS
- 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.

CONDITIONS FOR CLEARING THE MIL/DTC
- 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.

SPECIAL TOOLS REQUIRED
- J 46091 Charge Air Cooler Tester
- J 35616-200 Test Lamp Kit

CIRCUIT/SYSTEM VERIFICATION

IMPORTANT: If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

IMPORTANT: Verify that the engine is in good mechanical condition before continuing with this diagnostic.

Verify the integrity of the air induction system by inspecting for the following conditions:
- Restrictions in the MAF air induction system and the turbocharger system
- Restrictions in the exhaust system-Refer to Restricted Exhaust.
- Leaks in the charge air cooler with a J 46091
- Leaks at the MAF/IAT sensor O-ring seal
- Leaks at the MAP pressure sensor seal
- Cracked or damaged MAF sensor housing
- Restricted intake air duct or a dirty air filter element
- Debris blocking the air sensing filaments of the MAF sensor
- A MAF sensor that is installed backwards
- An exhaust gas recirculation (EGR) valve that is stuck open.

A skewed MAF sensor will also cause the predicted MAF value to disagree with the actual MAF sensor value. Use the scan tool to compare the MAF Sensor parameter to a known good vehicle under various operating conditions.

CIRCUIT/SYSTEM TESTING

IMPORTANT:
- If DTC P0405 is set, diagnose that DTC first.
- The DMM and test leads must be calibrated to 0 ohms in order to prevent misdiagnosis. Use the DMM to perform this test. Refer to the DMM User Manual for the calibration procedure.
- Use the J 35616-200 for this test. If the J 35616-200 is not available, use a test lamp that measures more than 20 ohms.

1. With the ignition ON, the engine OFF, the mass air flow (MAF) sensor disconnected, connect a test lamp between the MAF sensor 12-volt reference circuit and a good ground. Measure the voltage of the MAF sensor 12-volt reference circuit at the probe end of the test lamp, with a DMM connected to a good ground.
- If the voltage is less than battery voltage, test the circuit for a high resistance or a faulty ECM.
2. With the MAF sensor still disconnected, use the scan tool to observe the MAF Sensor parameter.
- If the MAF Sensor parameter is more than 0 volts, test the MAF sensor signal circuit for a short to voltage or a faulty ECM.
3. Connect a jumper wire between the MAF sensor signal circuit and the IAT sensor signal circuit. Use a scan tool to observe the MAF Sensor parameter for the proper value of more than 4.7 volts and 500 g/s.
- If the MAF Sensor parameter is less than 4.7 volts and 500 g/s, test the MAF sensor signal circuit for a high resistance or a faulty ECM.
4. Turn OFF the ignition, and all electrical accessories. Allow sufficient time for the control module to power down before taking a resistance measurement. With a DMM, measure the resistance between the low reference circuit of the MAF sensor and a good ground.
- If the resistance is more than 1.5 ohms, test the circuit for a high resistance or a faulty ECM.
- If the MAF sensor circuits test normal, replace the MAF sensor. Refer to Repair Instructions in this diagnostic.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Replacement for MAF/IAT sensor replacement
- Control Module References for ECM replacement, setup, and programming
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