P0101
DTC P0101 or P1101
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0101
- Mass Air Flow (MAF) Sensor Performance
DTC P1101
- Intake Air Flow System Performance
Diagnostic Fault Information
Typical Scan Tool Data
Circuit Description
The intake flow rationality diagnostic provides the within-range rationality check for the mass air flow (MAF), the manifold absolute pressure (MAP), and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing 4 separate models for the intake system.
* The throttle model describes the flow through the throttle body, and is used to estimate the MAF through the throttle body as a function of barometric pressure (BARO), TP, intake air temperature (IAT), and estimated MAP. The information from this model is displayed on the scan tool as the MAF Performance Test parameter.
* The first intake manifold model describes the intake manifold, and is used to estimate MAP as a function of the MAF into the manifold from the throttle body, and the MAF out of the manifold caused by engine pumping. The flow into the manifold from the throttle uses the MAF estimate calculated from the above throttle model. The information from this model is displayed on the scan tool as the MAP Performance Test 1 parameter.
* The second intake manifold model is identical to the first intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input. The information from this model is displayed on the scan tool as the MAP Performance Test 2 parameter.
* The fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model. The information from this model is displayed on the scan tool as the TP Performance Test parameter.
The estimates of MAF and MAP obtained from this system of models and calculations are then compared to the actual measured values from the MAF, the MAP, and the TP sensors and to each other to determine the appropriate DTC to fail. The following table illustrates the possible failure combinations and the resulting DTC or DTCs.
Conditions for Running the DTC
* DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0125, P0128, P0335, P0336, P0401, P0405, P1404 are not set.
* The engine speed is between 500-5,000 RPM.
* The IAT Sensor parameter is between -7 and +60°C (+19 and +140°F).
* The ECT Sensor parameter is between 70-121°C (158-250°F).
* This DTC runs continuously within the enabling conditions.
Conditions for Setting the DTC
The engine control module (ECM) detects that the actual measured airflow from the MAF, the MAP, and the TP sensors is not within range of the calculated airflow that is derived from the system of models for more than 0.5 second.
Action Taken When the DTC Sets
DTCs P0101 and P1101 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0101 and P1101 are Type B DTCs.
Diagnostic Aids
Caution: Refer to Road Test Caution.
* Road test the vehicle and verify that the MAF sensor calculated g/s and the actual MAF g/s parameters are near or equal to each other.
* A skewed MAF sensor, intake air flow restriction or intake air flow leak after the MAF sensor may cause the calculated g/s and MAF g/s parameters to disagree. Road test the vehicle while observing both parameters under various engine loads.
* 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 3-8 g/s at idle to 190 g/s or more at the time of the 1-2 shift.
* A steady or intermittent high resistance of 25 ohms or more on the ignition 1 voltage circuit will cause the MAF sensor values to be skewed high by up to 30 g/s. Use the scan tool to compare the MAF Sensor parameter to a known good vehicle under various operating conditions.
* A skewed or stuck engine coolant temperature (ECT) or IAT sensor will cause the calculated models to be inaccurate and may cause this DTC to run when it should not. Refer to Temperature Versus Resistance.
* The BARO that is used by the ECM to calculate the air flow models is initially based on the MAP sensor at ignition ON. When the engine is running, the ECM will continually update the BARO value near WOT using the MAP sensor and a calculation. A skewed MAP sensor will cause the BARO value to be inaccurate. Use the scan tool to compare the BARO parameter at ignition ON to the Altitude vs. Barometric Pressure table. Determine the altitude for your area and refer to Altitude Versus Barometric Pressure.
* A skewed MAP sensor will also cause the first and second intake manifold models to disagree with the actual MAP sensor measurements. Use the scan tool to compare the MAP Sensor parameter to a known good vehicle under various operating conditions.
Special Tools Required
J 38522 Variable Signal Generator
Circuit/System Verification
1. Verify the integrity of the air induction system by inspecting for the following conditions:
* 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
* Any water intrusion in the induction system
* Any vacuum leak downstream of the MAF/IAT sensor
* An intake manifold leak
* A MAP sensor seal that is missing or damaged
* A BARO sensor that is skewed or stuck
* A skewed or stuck ECT or IAT sensor-refer to Temperature Versus Resistance.
* Any type of restriction in the exhaust system-Refer to Restricted Exhaust. Restricted Exhaust
2. Ignition ON, observe the MAP Sensor parameter with a scan tool. Start the engine. The MAP Sensor parameter should decrease.
• If the MAP Sensor kPa parameter does not decrease, refer to DTC P0106. P0106
3. Ignition ON, depress the accelerator pedal completely and observe the TP Indicated Angle parameter with a scan tool. The TP Indicated Angle parameter should read 98-100 percent.
• If the TP Indicated Angle parameter is not within the specified range, refer to DTC P1516, P2101, P2119, or P2176. P1516
4. Ignition ON, perform a snapshot of the throttle actuator control (TAC) data while performing the following action. Refer to Scan Tool Snapshot Procedure. Component Tests and General Diagnostics
* Slowly depress the accelerator pedal to WOT position, then slowly release the pedal. Exit from the snapshot and review the data.
* Compare the TP Sensor 1 and the TP Sensor 2 parameters, frame by frame. The difference between the parameters should be less than 4 percent.
• If the TP Sensor 1 and Sensor 2 parameter difference is more than 4 percent, refer to DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135. P0120 P0122 P0123 P0220 P0222 P0223 P2135
5. Engine running, observe the DTC information with a scan tool. DTCs P0101 or P1101 should not set.
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
1. Ignition OFF, disconnect the harness connector at the MAF sensor.
2. Ignition OFF, allow sufficient time for the ECM to power down. Test for less than 5 ohms of resistance between the low reference circuit terminal D 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.
3. Ignition ON, test for 4.8-5.2 volts between the MAF sensor signal circuit terminal A and ground.
• If less than the specified range, test the MAF sensor 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 sensor signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Ignition ON, verify that a test lamp illuminates between the MAF sensor 12-volt reference voltage circuit terminal C and ground.
• If the test lamp does not illuminate, test the 12-volt reference circuit for a short to ground or an open/high resistance.
5. Connect the J 38522 to the vehicle.
Component Testing
Important: You must complete the Circuit/System Testing before proceeding with Component/System 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.
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
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Mass Airflow Sensor/Intake Air Temperature Sensor Replacement
* Control Module References for ECM replacement, setup, and programming Programming and Relearning