P0101
DTC P0101
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0101
- Mass Air Flow (MAF) Sensor Performance
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The mass air flow (MAF) sensor is integrated with the intake air temperature (IAT) sensor. The 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 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/IAT sensor has the following circuits:
* A MAF sensor ignition 1 voltage circuit
* A MAF sensor ground circuit
* A MAF sensor signal circuit
* An IAT sensor signal circuit
* An IAT sensor low reference circuit
The ECM applies 5 volts to the MAF sensor on the MAF sensor signal circuit. The sensor uses the voltage to produce a frequency based on the inlet airflow through the sensor bore. The frequency varies in a range depending on engine coolant temperature (ECT) of approximately 2,300 Hertz at idle to near 9,000 Hertz at maximum engine load.
Conditions for Running the DTC
* DTCs P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0642, P0643, P0652, P0653, P0698, P0699, P2228, P2229 are not set.
* The intake air temperature (IAT) is greater than -20°C (-4°F).
* The engine coolant temperature (ECT) is less than 99°C (210°F).
* The BARO is greater than 72 kPa.
* The engine speed is greater than 500 RPM.
* The exhaust gas recirculation (EGR) valve is not commanded ON.
* This DTC runs continuously within the enabling conditions.
Conditions for Setting the DTC
The ECM detects that the MAF sensor air flow ratio is not within a predetermined range of the calculated MAF air flow ratio for greater than 16 seconds.
Action Taken When the DTC Sets
* DTC P0101 is a Type A DTC.
* The ECM commands reduced engine power as a remedial action.
* The driver information center or indicator may display reduced engine power.
Conditions for Clearing the DTC
DTC P0101 is a Type A DTC.
Diagnostic Aids
* A slight to moderate resistance of 10-20 ohms on the MAF sensor ignition 1 voltage circuit may cause this DTC to set.
Caution: Refer to Road Test Caution.
* A skewed MAF sensor, an intake air flow restriction or any unmetered air that enters the engine downstream of the MAF sensor may cause this DTC to set.
* A wide open throttle (WOT) acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 6-38 g/s at idle to 380 g/s or more at the time of the 2-3 shift.
* An aftermarket exhaust system may reduce engine back-pressure excessively and cause this DTC to set.
Circuit/System Verification
1. Verify that DTCs P0047, P0048, P0102, P0103, P0403, or P0405 are not set.
• If any of the DTCs are set, Refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions
2. Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust. Restricted Exhaust
3. Verify that leaks do not exist in the exhaust system. Refer to Exhaust Leakage.
4. Engine operating at idle; observe the scan tool MAF Sensor parameter. The reading should be between 2,300-4,400 HZ depending on the ECT temperature.
5. A WOT acceleration from a stop should cause the MAF Sensor parameter on the scan tool to increase rapidly. This increase should be from 16-38 g/s at idle to greater than 400 g/s at the time of the 1-2 shift.
6. 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 Records data.
Circuit/System Testing
Important: You must perform the Circuit/System Verification before proceeding with the circuit/system testing.
1. Verify the integrity of the entire air induction system by inspecting for the following conditions:
* A loose or disconnected charge air cooler hose or pipe
* A restricted or collapsed air intake duct
* A misaligned or damaged air intake duct
* A dirty or deteriorating air filter element
* Any objects blocking the air inlet probe of the MAF/IAT sensor
* Any contamination or debris on the sensing elements in the probe of the MAF/IAT sensor
* A cracked or damaged MAF sensor housing
* Any water intrusion in the induction system
* Any snow or ice build-up a the air cleaner, MAF or MAP sensors in cold climates
* An intake manifold leak
* A MAP sensor seal that is missing or damaged
* An Intake Manifold Resonator with a leaking seal, or a cracked or broken housing
2. Ignition OFF, disconnect the harness connector at the MAF/IAT sensor.
3. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal 2 and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
4. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 3 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
5. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal 1 and ground.
• If less than the specified range, test the MAF signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
• If greater than the specified range, test the MAF signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
6. Test the charge air cooler system for leaks.
7. Remove the air inlet tube to intake manifold.
8. Visually inspect the EGR valve and verify the valve is in the closed position.
• If the EGR valve is not in the closed position, replace the EGR valve.
9. If all circuits, the charge air cooler, and EGR valve test normal, test the MAF/IAT sensor.
Component Testing
Important: You must perform the Circuit/System Testing in order to verify the integrity of the MAF sensor circuits before proceeding with the Component Testing.
To determine if the ECM can properly process the MAF sensor frequency signal, connect the J 38522 to the vehicle as follows:
1. Turn OFF the ignition, disconnect the connector at MAF/IAT sensor.
2. Connect the battery voltage supply and ground the black lead.
3. Connect the red lead to the signal circuit terminal A of the MAF sensor.
4. Set the duty cycle switch to Normal.
5. Set the Frequency switch to 5 K.
6. Set the signal switch to 5 volts.
7. Start the engine, observe the MAF Sensor parameter for the correct range of 4,950-5,025 Hz.
• If the MAF Sensor parameter is not within the specified range, replace the ECM.
• If the MAF Sensor parameter is within the specified range, replace the MAF sensor.
Repair Instructions
Notice: After performing the system repair, perform the following:
* A code clear with a scan tool, regardless of whether or not a DTC is set
* A Diesel Particulate Filter (DPF) Regeneration Enable with a scan tool
Perform the above to avoid possible soot overloading conditions or possible damage to the DPF.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Exhaust Particulate Filter Cleaning (DPF Service Regeneration) Exhaust Particulate Filter Cleaning (DPF Regeneration Enable)
* Mass Airflow Sensor/Intake Air Temperature Sensor Replacement
* Control Module References for ECM replacement, setup, and programming Programming and Relearning Verification Tests