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 Descriptors
DTC P0101: Mass Air Flow (MAF) Sensor PerformanceDTC P1101: Intake Air Flow System 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
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
Ignition 1 Voltage | -- | 0-2 g/s | 0-2 g/s | -- |
MAF Sensor Signal | 3-225 g/s | 0-2 g/s | 0-2 g/s | 0-2 g/s |
Ground | -- | -- | 0-2 g/s | -- |
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 (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 derived from this model is the MAF Performance Test. |
| • | 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 derived from this model is the MAP Performance Test 1. |
| • | 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 derived from this model is the MAP Performance Test 2. |
| • | The fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model. The information derived from this model is the TP Performance Test. |
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 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.
MAF Performance Test | MAP Performance Test 1 | MAP Performance Test 2 | TP Performance Test | DTCs Passed | DTCs Failed |
|---|---|---|---|---|---|
X | X | OK | OK | P0101, P0106, P0121, P1101 | None |
OK | OK | Fault | OK | P0101, P0106, P0121, P1101 | None |
Fault | OK | Fault | OK | P0106, P0121, P1101 | P0101 |
OK | Fault | Fault | OK | P0101, P0121, P1101 | P0106 |
Fault | Fault | Fault | OK | P0121, P1101 | P0101, P0106 |
X | X | OK | Fault | P0101, P0106, P1101 | P0121 |
OK | OK | Fault | Fault | P0101, P0106, P0121, P1101 | None |
Fault | OK | Fault | Fault | P0101, P0106, P0121 | P1101 |
X | Fault | Fault | Fault | P0101, P0106, P0121 | P1101 |
Conditions for Running the DTCs
| • | DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0335, P0336 are not set. |
| • | The engine speed is between 400-8,192 RPM. |
| • | The IAT Sensor parameter is between -7 to +125°C (+19 to +257°F). |
| • | The ECT Sensor parameter is between 70-125°C (158-257°F). |
| • | This DTC runs continuously within the enabling conditions. |
Conditions for Setting the DTC
The powertrain control module (PCM) 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
| • | DTC P0101 is a Type B DTC. |
| • | DTC P1101 is a Type B DTC. |
Conditions for Clearing the MIL/DTC
| • | DTC P0101 is a Type B DTC. |
| • | DTC P1101 is a Type B DTC. |
Diagnostic Aids
| • | A steady or intermittent high resistance of 15 ohms or greater on the ignition 1 voltage circuit will cause the MAF sensor signal to be increased by as much as 60 g/s. To pinpoint this condition perform a voltage drop test on the circuit. |
| • | Any type of contamination on the MAF sensor heating elements will degrade the proper operation of the sensor. Certain types of contaminants act as a heat insulator, which will impair the response of the sensor to airflow changes. Water or snow can create the opposite effect, and cause the signal to increase rapidly. |
| • | 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 increase or decrease the MAF sensor signal that is interpreted by the PCM. Additionally it may cause a rapid fluctuation in the IAT Sensor parameter. |
| • | 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 . |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
| • | If DTC P0641 or DTC P0651 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
| • | 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 leak |
| - | Water intrusion |
| - | In cold climates, inspect for any snow or ice buildup |
| • | Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust . |
| • | Engine idling, observe the scan tool MAF Sensor parameter. The reading should be between 3-10 g/s depending on the ECT. |
| • | 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 3-10 g/s at idle to greater than 200 g/s at the time of the 1-2 shift. |
| • | The BARO that is used by the PCM to calculate the air flow models is initially based on the MAP sensor at ignition ON. When the engine is running, the PCM 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. Determine the current vehicle testing altitude. Ignition ON, observe the scan tool BARO sensor parameter. Compare the parameter to the Altitude vs Barometric Pressure table. 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 and compare the MAP Sensor parameter to a known good vehicle, under various operating conditions. |
Circuit/System Testing
- Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
- Ignition OFF, test for less than 5 ohms of resistance between the ground circuit terminal B and ground.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal C and ground.
- Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal A and ground.
- If the MAF sensor circuits test normal, test the frequency output of the MAF sensor. Refer to Component Testing for instructions.
Important: All electrical components and accessories must be turned OFF, and allowed to power down.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. |
| ⇒ | 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 PCM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the PCM. |
Component Testing
- Ignition OFF, disconnect the MAF/IAT harness connector at the MAF/IAT sensor.
- Connect a set of jumper wires between the MAF/IAT harness connector and the MAF/IAT sensor.
- Idle or drive the vehicle to completely warm-up the ECT to the normal operating range.
- Engine idling, test for 1,500-3,500 Hz. between the signal circuit terminal A and ground with a DMM.
| ⇒ | If the frequency is not within the specified range, replace the MAF sensor. |
| ⇒ | If the frequency is within the specified range, replace the PCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for PCM replacement, setup, and programming |
