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DTC P0101 (LF1, LFW)

DTC P0101 (LF1, LFW)

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

Circuit Short to Ground High Resistance Open Short to Voltage Signal Performance
Ignition 1 Voltage P0102 P0101 P0102 - P0101, P0103
MAF Sensor Signal P0102 P0102 P0102 P0102 P0101, P0103, P1101
Ground - P0102 P0102 - P0102


Typical Scan Tool Data

MAF Sensor

Circuit Short to Ground Open Short to Voltage
Operating conditions: Engine running at various operating conditions Parameter Normal Range: 2,000-10,000 Hz
Ignition Voltage 0 Hz 0 Hz -
MAF Sensor Signal 0 Hz 0 Hz 0 Hz
Ground - 0 Hz -


Circuit Description

The intake flow rationality diagnostic provides the within-range rationality check for the mass air flow (MAF), manifold absolute pressure (MAP), and the throttle position 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), throttle position sensors, 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 Throttle Position Sensors 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, MAP, and the throttle position 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.

Scan Tool Diagnostic Test Results

MAF Performance Test MAP Performance Test 1 MAP Performance Test 2 Throttle Position Sensors Performance Test DTCs Passed DTCs Failed
- - OK OK P0101, P0106, P0121, P1101 None
OK OK Malfunction OK P0101, P0106, P0121, P1101 None
Malfunction OK Malfunction OK P0106, P0121, P1101 P0101
OK Malfunction Malfunction OK P0101, P0121, P1101 P0106
Malfunction Malfunction Malfunction OK P0121, P1101 P0101, P0106
- - OK Malfunction P0101, P0106, P1101 P0121
OK OK Malfunction Malfunction P0101, P0106, P0121, P1101 None
Malfunction OK Malfunction Malfunction P0101, P0106, P0121 P1101
- Malfunction Malfunction Malfunction P0101, P0106, P0121 P1101
OK OK Malfunction OK - P0102


Conditions for Running the DTCs


• DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0335 or P0336 are not set.

• Engine is running.

• The engine coolant is between 69 and 127°C (156 and 261°F).

• The intake air temperature is between -20 and +125°C (-4 and +257°F).

• The DTC runs continuously once the above conditions are met.


Conditions for Setting the DTC

The engine control module (ECM) detects that the actual measured airflow from the MAF, MAP, and throttle position sensors is not within range of the calculated airflow that is derived from the system of models for greater than 2 s.

Action Taken When the DTC Sets

DTC P0101 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0101 is a Type B DTC.

Diagnostic Aids


• A steady or intermittent high resistance of 15 Ω or greater on the ignition voltage circuit will cause the MAF sensor signal to be increased by as much as 60 g/s.

• Depending on the current ambient temperature, and the vehicle operating conditions, a MAF sensor signal circuit that is shorted to the IAT signal circuit will cause the MAF sensor signal to be skewed or erratic. Additionally, it may cause a rapid fluctuation in the IAT Sensor parameter.

• Certain aftermarket air filters may cause this DTC to set.

• Certain aftermarket air induction systems may cause this DTC to set.

• Modifications to the air induction system may cause this DTC to set.


Reference Information

Schematic Reference

Engine Controls Schematics (3.0L (LF1)) Engine Controls Schematics (2.8L (LAU))

Connector End View Reference

Component Connector End Views

Electrical Information Reference


• Circuit Testing

• Connector Repairs

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs


DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 38522 Variable Signal Generator

Circuit/System Verification


1. Verify that the following DTCs are not set:

• 5 V reference circuits

• Camshaft position system performance

• Engine controls ignition relay circuits

• Ignition circuits-Body control module (BCM)

2. If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

3. Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust .

4. Engine operating at idle, observe the scan tool MAF Sensor parameter. The reading should be between 2,000-3,800 Hz depending on the ECT.

5. 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 2-6 g/s at idle to greater than 180 g/s at the time of the 1-2 shift.

6. Use the scan tool and compare the MAF Sensor parameter to a known good vehicle, under various operating conditions.

7. Verify the proper operation of the ECT and IAT sensors. A skewed or stuck 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 - Intake Air Temperature Sensor .

8. Verify the proper operation of the MAP sensor. A skewed MAP sensor will cause the BARO value to be inaccurate. Refer to DTC P0106 (LF1) .

9. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.


Circuit/System Testing


1. Verify the integrity of the entire air induction system by inspecting for the following conditions:

• Any damaged components

• Loose or improper installation

• An air flow restriction

• Any vacuum leaks

• Water intrusion

• In cold climates, inspect for any snow or ice buildup

• Inspect the B75B MAF/IAT sensor element for contamination.

2. Ignition OFF, disconnect the harness connector at the B75B MAF/IAT sensor.

3. Ignition OFF, remove the fuse that supplies B+ to terminal 52 X1 of the ECM.

4. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 Ω between the ground circuit terminal B and ground.

5. If greater than the specified range, test the ground circuit for an open/high resistance.

6. Install fuse that supplies B+ to terminal 52 X1 of the ECM.

7. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal C and ground.

8. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

9. Ignition ON, test for 4.8-5.2 V between the signal circuit terminal A and ground.

10. If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

11. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

12. Ignition OFF, connect the red lead of the J 38522 to the signal circuit terminal A at the B75B MAF/IAT sensor harness connector. Connect the battery voltage supply to B+, and the black lead to ground.

13. Set the J 38522 Signal switch to 5 V, the Frequency switch to 5K, and the Duty Cycle switch to Normal.

14. With the ignition ON, check the scan tool's parameter for the MAF sensor. The scan tool MAF Sensor parameter should be between 4,950-5,050 Hz.

15. If the MAF Sensor parameter is not within the specified range, replace the K20 ECM.

16. If all other circuits test normal, test or replace the B75B MAF/IAT sensor.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.


• Engine Coolant Temperature Sensor Replacement (LAU) Engine Coolant Temperature Sensor Replacement (LF1)

• Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (LAU) Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (LF1)

• Control Module References for ECM replacement, setup, and programming