P0068
DTC P0068 or P1101 (LUW)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0068
- Throttle Body Air Flow Performance
DTC P1101
- Intake Air Flow System Performance
Circuit/System Description
The engine control module (ECM) compares actual airflow based on throttle position to a calculated airflow based on manifold absolute pressure (MAP) sensor, and mass air flow (MAF).
Conditions for Running the DTC
P0068
* The engine speed is greater than 800 RPM.
* The ignition voltage is greater than 6.41 V.
* The throttle actuator control system is not in reduced power mode.
P1101
* DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0128, P0222, P0223, P0335, P0336 are not set
* The engine speed is between 400-6 000 RPM
* The engine coolant temperature (ECT) Sensor is between -7 to + 125°C (19.4 to +257°F).
* The intake air temperature (IAT) Sensor is between -20 to +100°C (-4 to +212°F).
Conditions for Setting the DTC
The ECM detects that the airflow rate is more than the calculated airflow for more than 0.2 s.
Action Taken When the DTC Sets
* DTC P0068 is a Type A DTC.
* DTC P1101 is a Type B DTC.
Conditions for Clearing the DTC
* DTC P0068 is a Type A DTC
* DTC P1101 is a Type B DTC.
Diagnostic Aids
* A steady or intermittent high resistance of 15 ohm 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.
* Use a solution of dish soap and water in a spray bottle to pinpoint any suspected air leaks in the induction system. This includes vacuum lines, positive crankcase ventilation system, intake manifold, throttle body, charge air cooler assembly.
Reference Information
Schematic Reference
Engine Controls Schematics (LUW) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left (D6I)
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Testing
1. Verify none of the following conditions exist:
* The air intake duct system for loose clamps, cracks, or other damage.
* The air intake duct system for being collapsed or restricted.
* The B75 Mass Air Flow Sensor is installed correctly. The arrow indicates direction of airflow and the tabs of the hoses and notches of the sensor must be aligned.
* Restricted air filter.
* Q38 Throttle Body for dirt, debris, and coking. Also, Q38 Throttle Body blade or shaft damage. Refer to Throttle Body Inspection and Cleaning (1.6L LDE, LXV, 1.8L 2H0, and LUW) Procedures for further diagnosis.
* Splits, kinks, or improper connections at the vacuum hoses.
* Missing, restricted, or leaking exhaust components. Refer to Symptoms - Engine Exhaust Symptoms - Engine Exhaust.
* Vacuum leaks at the intake manifold, Q38 Throttle Body, and injector O-rings.
* Improper positive crankcase ventilation system operation.
• If a condition exists, repair as necessary.
2. Ignition ON, observe the diagnostic trouble code (DTC) information with a scan tool. Verify that DTCs P0641, P0651, P0697, or P06A3 are not set.
• If any of the above DTCs are set. Refer to DTC P0641, P0651, P0697, or P06A3 (LUW) Powertrain Management.
3. Determine the current vehicle testing altitude. Compare the MAP sensor pressure parameter to the reading in the Altitude Versus Barometric Pressure Altitude Versus Barometric Pressure table. The MAP sensor pressure parameter should be within the specified range indicated in the table.
• If the MAP sensor pressure is not within the range specified for your altitude. Refer to Altitude Versus Barometric Pressure Altitude Versus Barometric Pressure.
4. Engine idling, observe the MAP Sensor parameter. The reading should be between 26-52 kPa (3.8-7.5 PSI).
• If not within the specified range. Refer to DTC P0106, P0107, or P0108 (LUW) P0106.
5. Use the scan tool snapshot function to take a snapshot of the engine data list while performing the actions listed below.
1. Engine idling
2. Increase the engine speed slowly to 3 000 RPM and then back to idle.
3. Exit from the scan tool snapshot and review the data.
4. Observe the MAF sensor parameter frame by frame with a scan tool. The MAF sensor g/s parameter should change smoothly and gradually as the engine speed is increased and then returned to idle.
• If the MAF sensor g/s does not change smoothly and gradually. Refer to DTC P0101 (LUW) P0101 for further diagnosis.
6. If all conditions test normal, test the engine for a mechanical condition. Refer to Symptoms - Engine Mechanical Symptoms - Engine Mechanical.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Throttle Body Assembly Replacement (1.6L LDE, LXV, 1.8L 2H0, and LUW) Removal and Replacement
* Air Cleaner Element Replacement (1.6L LDE, LXV, 1.8L 2H0, LUW and LFH) Service and Repair
* Positive Crankcase Ventilation Hose/Pipe/Tube Replacement (1.6L LDE, LXV, 1.8L 2H0, LUW and LFH) Service and Repair
* Mass Airflow Sensor Replacement Service and Repair