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, P1101 | P0102 | -- | P0101, P0103, P1101 |
MAF Sensor Signal | P0102 | P0102, P1101 | P0102 | P0102 | P0101, P0103, P1101 |
Ground | -- | P0102, P1101 | P0102 | -- | P0102, P1101 |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine running at various operating conditions Parameter Normal Range: 1,700-9,500 Hz | |||
Ignition 1 Voltage | 0 Hz | 0 Hz | -- |
MAF Sensor Signal | 0 Hz | 0 Hz | 0 Hz |
Ground | -- | 0 Hz | -- |
Circuit Description
Important: The following applies to the intake airflow system performance diagnostic that is used in this supercharged engine:
• When referring to the supercharger intake manifold models, the plenum volume between the throttle body and the supercharger is considered to be the intake manifold. • When referring to engine pumping, the supercharger and the intercooler plenum are considered to be part of the engine. • The manifold absolute pressure (MAP) estimates are used in the engine air flow estimates. Air flow into the intake system must be the same as the air flow out of the intake system, the Intake Airflow Rationality Diagnostics (IFRD) calculates air
flowing out of the engine based on MAP estimates, volumetric efficiency, and RPM.
The intake airflow system performance diagnostic provides the within-range rationality check for the mass air flow (MAF), supercharger inlet absolute pressure (SCIAP), MAP, by-pass valve stuck, 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), throttle position, intake air temperature (IAT), and estimated SCIAP. The information from this model is displayed on the scan tool as the MAF Performance Test parameter. |
| • | The first supercharger intake manifold model describes the pressure at the supercharger intake manifold and is used to estimate SCIAP as a function of the MAF into the intake manifold from the throttle body and the MAF out of the intake manifold caused by engine pumping. The flow into the supercharger intake 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 supercharger intake manifold model is identical to the first supercharger 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. |
| • | A fourth model is created from the combination and additional calculations of the throttle model and the first supercharger intake manifold model. The information from this model is displayed on the scan tool as the TP Performance Test parameter. |
| • | In addition 5 new models have been added, these models run in the background. |
The estimates of MAF, SCIAP, and TP that are obtained from this system of models and calculations are then compared to the actual measured values from the MAF, SCIAP, 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 |
-- | -- | OK | OK | P0101, P0121, P012B, P1101 | None |
OK | OK | Fault | OK | P0101, P0121, P012B, P1101 | None |
Fault | OK | Fault | OK | P0121, P012B, P1101 | P0101 |
OK | Fault | Fault | OK | P0101, P0121, P1101 | P012B |
Fault | Fault | Fault | OK | P0121, P1101 | P0101 P012B |
-- | -- | OK | Fault | P0101, P012B, P1101 | P0121 |
OK | OK | Fault | Fault | P0101, P0121, P012B, P1101 | None |
Fault | OK | Fault | Fault | P0101, P0121, P012B | P1101 |
-- | Fault | Fault | Fault | P0101, P0121, P012B, P1101 | P0101, P1101 |
Conditions for Running the DTC
| • | DTCs P0096, P0097, P0098, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0116, P0117, P0118, P012C, P012D, P0335, P0336, P0401, P0405, P1404, P2226, P2227, P2228 are not set. |
| • | The engine speed is running. |
| • | The intake air temperature is between -7 and +125°C (+19 and +257°F). |
| • | The engine coolant temperature is between 70-121°C (158-250°F). |
| • | This DTC runs continuously when the above enabling conditions are met. |
Conditions for Setting the DTC
The engine control module (ECM) detects that the actual measured airflow from the MAF, MAP, SC Inlet Pressure, and the TP sensors are not within a range of the calculated airflow that are derived from the system of models by greater than a calibrated threshold for greater than 10 seconds.
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
Inspect for the following conditions that may set this DTC:
| • | Any condition that can cause the MAF, MAP, SCIAP, and TP sensors to be shifted in value. |
| • | A slight to moderate resistance of 10-20 ohms on the MAF sensor ignition or ground circuits may cause this DTC to set. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Special Tools
J 38522 Variable Signal Generator
Circuit/System Verification
- Verify that the following DTCs are not set: P0641 or P0651.
- Verify restrictions do not exist in the exhaust system--Refer to Restricted Exhaust.
- Ignition ON, observe the MAP Sensor and SC Inlet Pressure Sensor kPa parameters with a scan tool. Start the engine and let it idle. The MAP and SC Inlet Pressure Sensor kPa parameters should decrease and closely match each other.
- Ignition ON, depress the accelerator pedal completely to wide open throttle (WOT) and observe the TP Indicated Angle parameter with a scan tool. The TP Indicated Angle parameter should read 98-100 percent.
- Ignition ON, engine OFF, perform a snapshot of the throttle actuator control (TAC) data while performing the following actions. Refer to Scan Tool Snapshot Procedure.
- Road test the vehicle and perform a brief wide open throttle (WOT) acceleration from 30 mph. The MAP sensor parameter on the scan tool should increase rapidly. This increase should be from approximately 35 kPa at idle to greater than 135 kPa.
- 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 or stuck ECT, BARO, MAP, MAF/IAT, or IAT sensor 2 will cause the calculated models to be inaccurate and may cause this DTC to run when it should not. Refer to Temperature Versus Resistanceand Altitude Versus Barometric Pressure.
- 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.
| ⇒ | If any of the DTCs are set, refer to DTC P0641 or P0651 |
| ⇒ | If the MAP Sensor kPa parameter does not decrease and closely match each other, refer to DTC P0106. |
| ⇒ | If the SC Inlet Pressure kPa parameter does not decrease and closely match each other, refer to DTC P012B. |
| ⇒ | If the TP Indicated Angle parameter is not within the specified range, refer to DTC P1516, P2101, P2119, or P2176. |
| 5.1. | Slowly depress the accelerator pedal to WOT position and then slowly release the pedal. Exit from the snapshot and review the data. |
| 5.2. | Compare the TP Sensor 1 Indicated Position and the TP Sensor 2 Indicated Position parameters, frame by frame. The difference between the values should be less than 4 percent. |
| ⇒ | If the difference is greater than 4 percent, refer to DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135. |
| ⇒ | If the MAP Sensor parameter does not increase to greater than the specified range, refer to Boost Control System Diagnosis. |
Circuit/System Testing
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Visually and physically inspect the by-pass valve and cable for any of the following conditions:
- Verify the integrity of the entire supercharger air induction system by inspecting for the following conditions:
- Ignition OFF and scan tool disconnected, disconnect the harness connector at the MAF sensor.
- Ignition OFF for 90 seconds, test for less than 5 ohms between the ground circuit terminal B and ground.
- Ignition ON, test for 4.8-5.2 volts between the MAF sensor signal circuit terminal A and ground.
- Ignition ON, verify that a test lamp illuminates between the MAF sensor ignition 1 voltage circuit terminal C and ground.
- Ignition OFF, connect the read lead of J 38522 to the signal circuit terminal A at the MAF/IAT sensor harness connector. Connect the battery voltage supply to B+. Connect the black lead to ground.
- Set the J 38522 signal to 5 volts, the Frequency to 5K, and the Duty Cycle to Normal.
- Engine idling, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 4,950-5,025 Hz.
- If all circuits test normal, test or replace the MAF Sensor.
| • | A binding or sticking when opening or closing |
| • | An incorrectly adjusted cable |
| ⇒ | If any of the above conditions are found, refer to Supercharger Cleaning and Inspection. |
| • | 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 unmetered air downstream of the MAF/IAT sensor |
| • | An intake manifold leak |
| • | Any snow or ice build up at the air cleaner or MAF/IAT sensor |
| • | A SCIAP sensor vacuum hose that is missing or damaged |
| • | A MAP sensor vacuum hose that is missing or damaged |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | 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. |
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. |
| ⇒ | If the MAF Sensor parameter is not within the specified range, replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
