Engine Controls/fuel - 2.4l - DTC p0010 to DTC p0418 Buick LaCrosse II

Connector End View Reference

Camshaft Actuator System Description

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the DTC information with a scan tool. Verify DTC P0335, P0336, P0340, P0341, P0365, or P0366 is not set. If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for further diagnosis.
Observe the appropriate control circuit status parameters listed below with a scan tool: The Exhaust/Intake Camshaft Position Actuator Solenoid Valve Control Circuit Open test status The Exhaust/Intake Camshaft Position Actuator Solenoid Valve Control Circuit High Voltage test status The Exhaust/Intake Camshaft Position Actuator Solenoid Valve Control Circuit Low Voltage test status Each parameter should display OK or Not Run
Engine idling, command the Camshaft Position Actuator to 20° while observing the following control circuit status parameters with a scan tool: The Exhaust/Intake Camshaft Position Actuator Solenoid Valve Control Circuit Open test status The Exhaust/Intake Camshaft Position Actuator Solenoid Valve Control Circuit High Voltage test status The Exhaust/Intake Camshaft Position Actuator Solenoid Valve Control Circuit Low Voltage test status Each parameter should display OK or Not Run
Engine at normal operating temperature, raise the engine speed to 2, 000 RPM for 10 s. DTC P0010 or P0013 should not set.
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

Ignition OFF, disconnect the harness connector at the appropriate Q6 camshaft position actuator solenoid valve.
Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal A and ground. If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
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 ohms between the low reference circuit terminal B and ground. If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
Ignition ON, connect the DMM black lead to the control circuit terminal A. Connect the DMM red lead to B+. Set the DMM on the diode setting. Command the CMP actuator solenoid ON and OFF with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON. If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the K20 engine control module.
If all circuits/connections test normal, test or replace the appropriate Q6 camshaft position actuator solenoid valve.

Component Testing

Ignition OFF, disconnect the harness connector at the appropriate Q6 camshaft position actuator solenoid valve.
Test for 8-13 ohms between the control terminal A and the low reference circuit terminal B of the Q6 camshaft position actuator solenoid valve. If not within the specified range, replace the Q6 camshaft position actuator solenoid valve.
Test for infinite resistance between each terminal and the Q6 camshaft position actuator solenoid valve housing. If not the specified value, replace the Q6 camshaft position actuator solenoid valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

«Camshaft Position Actuator Exhaust Solenoid Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Camshaft Position Actuator Intake Solenoid Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming, and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The camshaft position actuator system enables the engine control module (ECM) to change the timing of the camshafts while the engine is operating. The camshaft position actuator solenoid signal from the ECM is pulse width modulated (PWM). The ECM controls the camshaft position actuator solenoid duty cycle by controlling the amount of solenoid ON time. The camshaft position actuator solenoid controls the advance or the retard of each camshaft. The camshaft position actuator solenoid controls the oil flow that applies the pressure to advance or retard the camshafts.

DTC P0010, P0013, P0016, P0017, P0335, P0336, P0340, P0341, P0365, or P0366 is not set.
The ignition voltage is greater than 11 V.
The engine is operating.
The desired camshaft position is not changing greater than 4.5 degrees for at least 1 s.
Both of the desired and actual camshaft position actuator values cannot be greater than 25 degrees or less than 5 degrees.
DTCs P0011 and P0014 run continuously once the above conditions are met.

The ECM detects the difference between the desired camshaft position angle and the actual camshaft position angle is greater than 5 degrees for greater 2.5 s.

DTCs P0011 and P0014 are Type B DTCs.
The Auto Stop and Auto Start function of the hybrid system is disabled.

DTCs P0011 and P0014 are Type B DTCs.

The engine oil condition has a major impact on the camshaft actuator system.
A low oil level condition may set this DTC. The engine may require an oil change. Inquire with the customer when the last oil change was performed. You may also monitor the scan tool Engine Oil Life Remaining parameter. Advise the customer an oil change may be required.
Inspect the engine for any recent engine mechanical repairs. An incorrectly installed camshaft, camshaft actuator, or timing chain may cause this DTC to set.

Schematic Reference

Connector End View Reference

Camshaft Actuator System Description

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Verify the engine has the correct oil pressure. Refer to «Oil Pressure Diagnosis and Testing»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__oil-pressure-diagnosis-and-testing) .
Ignition ON, observe the scan tool DTC information. Verify that DTC P0010, P0013, P0016, P0017, P0335, P0336, P0340, P0341, P0365, or P0366 is not set. If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for further diagnosis.
Engine idling, command the appropriate Camshaft Position Actuator from 0 degrees to 20 degrees and back to zero while observing the appropriate scan tool Intake/Exhaust Camshaft Position Variance parameters. The Intake/Exhaust Camshaft Position Variance should be less than 2 degrees in each of the commanded states.
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.

Ignition OFF, disconnect the harness connector at the appropriate Q6 camshaft position actuator solenoid valve.
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 ohms between the low reference circuit terminal B and ground. If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal A and ground. If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
Ignition ON, command the appropriate Camshaft Position Actuator Solenoid Valve from OFF to ON with a scan tool while observing the appropriate scan tool Camshaft Position Actuator Solenoid Valve Control Circuit Low Voltage Test Status. the value should toggle between OK and Not run in each of the commanded states. If the parameter does not correspond to the specified values, test the control circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the K20 engine control module.
Remove the Q6 camshaft position actuator solenoid valve. Verify the following conditions do not exist with the camshaft position actuator solenoid valve: Torn, restricted, mis-positioned, or missing screens at the CMP actuator solenoid Engine oil leak between the oil sealing lands of the CMP actuator solenoid. Inspect the lands of the CMP actuator solenoid for nicks. Oil seepage at the CMP actuator solenoid connector If a condition is found, replace Q6 camshaft position actuator solenoid valve.
Ignition OFF, swap the appropriate Q6 camshaft position actuator solenoid valve with a Q6 camshaft position actuator solenoid valve that is operating correctly.
Engine idling, command the appropriate Camshaft Position Actuator from 0 degrees to 20 degrees and back to zero while observing the appropriate scan tool Intake/Exhaust Camshaft Position Variance parameters. The Intake/Exhaust Camshaft Position Variance should be less than 2 degrees in each of the commanded states. If greater than the specified value, replace the appropriate mechanical camshaft position actuator.
If all circuits/connections test normal, test or replace the Q6 camshaft position actuator solenoid valve.

Ignition OFF, disconnect the harness connector at the appropriate Q6 camshaft position actuator solenoid valve.
Test for 8-13 ohms between the control terminal A and the low reference circuit terminal B of the Q6 camshaft position actuator solenoid valve. If not within the specified range, replace the Q6 camshaft position actuator solenoid valve.
Test for infinite resistance between each terminal and the Q6 camshaft position actuator solenoid valve housing. If not the specified value, replace the Q6 camshaft position actuator solenoid valve.

Perform the Diagnostic Repair Verification after completing the repair.

«Camshaft Position Actuator Exhaust Solenoid Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Camshaft Position Actuator Intake Solenoid Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Camshaft Position Intake Actuator Replacement»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__camshaft-position-intake-actuator-replacement)
«Camshaft Position Exhaust Actuator Replacement»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__camshaft-position-exhaust-actuator-replacement)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming, and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) uses the crankshaft position (CKP) sensor and the intake and exhaust camshaft position (CMP) sensor information to monitor the correlation between the crankshaft, intake, and exhaust camshaft position.

DTC P0335, P0336, P0340, P0341, P0365, P0366, P0641, and P0651 are not set.
The engine is cranking or running.
The crankshaft and camshaft position signals are synchronized.
The camshaft position actuator is in the parked position.
DTC P0016 and P0017 run continuously once the above conditions are met.

The ECM detects a camshaft that is greater than 10 degrees advanced, or 10 degrees retarded, in relationship to the crankshaft.

DTCs P0016 and P0017 are type B DTCs.

Inspect the engine for any recent engine mechanical repairs. An incorrectly installed timing chain can cause this DTC to set.
An actuator that is in the full advance or retard position can cause this DTC to set.

Schematic Reference

Connector End View Reference

Camshaft Actuator System Description

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the DTC information with a scan tool. Verify that none of the following DTCs are set. DTC P0010, P0013, P0335, P0336, P0340, P0341, P0365, or P0366. If any of the DTCs listed are set refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for further diagnosis.
Idle the engine at normal operating temperature. DTCs P0016 or P0017 should not set. If a DTC sets, inspect for the following and repair as necessary: The correct installation of the camshaft sensors The correct installation of the crankshaft sensor A timing chain tensioner condition An incorrectly installed timing chain Excessive play in the timing chain A mechanical cam actuator that is stuck in the full advance or retard position A timing chain that jumped teeth
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.

Perform the Diagnostic Repair Verification after completing the repair.

«Camshaft Timing Chain and Sprocket Cleaning and Inspection»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__camshaft-timing-chain-and-sprocket-cleaning)
«Camshaft Timing Chain, Sprocket, and Tensioner Replacement»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l)

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
HO2S Heater Voltage Supply	P0030, P0036, P0132, P0135, P0138, P0141, *	P0030, P0036, P0132, P0134, P0135, P0138, P0140, P0141	P0030, P0036, P0132, P0134, P0135, P0138, P0140, P0141	P0690	P0135, P0141
HO2S Heater Control	P0030, P0036, P0053, P0054, P0135, P0141	P0030, P0036, P0132, P0134, P0135, P0138, P0140, P0141	P0030, P0036, P0132, P0134, P0135, P0138, P0140, P0141	P0030, P0036, P0132, P0134, P0135, P0138, P0140, P0141	P0135, P0141
* Opens fuse

Circuit Description

The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensors rate of heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature, the ECM may modulate the heater control circuit to ground, to maintain a desired temperature.

The ECM controls the heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

P0030 or P0036

The ignition voltage is between 11-32 V.
The engine speed is greater than 400 RPM.
The DTCs run continuously once the above conditions are met for 10 s.

P0053 or P0054

DTCs P0112, P0113, P0117, P0118, P0128, P2610 are not set.
The engine is running.
Ignition voltage is less than 32 V.
The ignition is OFF for more than 8 h.
The Engine Coolant Temperature (ECT) Sensor parameter is between -30 to +45°C (-22 to +113°F) at engine start-up.
DTCs P0053 and P0054 run once per drive cycle when the above conditions are met.

P0135

DTCs P0116, P0117, P0118, P0128 are not set.
The ECT Sensor parameter is more than 70°C (158°F).
The Ignition 1 Signal parameter is between 10-32 V.
DTC P0135 runs twice per drive cycle when the above conditions are met for 2 min.

P0141

DTCs P0116, P0117, P0128 are not set.
The ECT Sensor parameter is more than 70°C (158°F).
The Ignition 1 Signal parameter is between 10-32 V.
DTC P0141 runs twice per drive cycle when the above conditions are met for 2 min.

P0030 or P0036

The ECM detects that the affected HO2S heater low control circuit voltage is not within a specified range.
DTCs P0030 and P0036 set within 3 s when the above condition is met.

P0053 or P0054

The ECM detects that the affected HO2S heater low control circuit resistance is not within a specified range at engine start-up.
DTCs P0053 and P0054 set within 1 s when the above condition is met.

P0135

The ECM detects that the affected HO2S 1 heater current parameter is more than 2.5 A or less than 0.3 A.
DTC P0135 sets within 60 s when the above condition is met.

P0141

The ECM detects that the affected HO2S 2 heater current parameter is more than 2.5 A or less than 0.3 A.
DTC P0141 sets within 60 s when the above condition is met.

DTCs P0030, P0036, P0053, P0054, P0135, and P0141 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0030, P0036, P0053, P0054, P0135, and P0141 are Type B DTCs.

If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool circuit test status parameters for the component. The circuit test status parameters change from OK or Not Run to Malfunction if there is a condition with the circuit or a connection.
An open fuse in the HO2S heater circuit may be caused by the heater element in one of the sensors. The condition may not be present until the sensor operates for a period of time. If no fault is present in the heater circuit, monitor the amperage of each heater using the DMM to determine if one of the heater elements is the cause of the open fuse. Inspect the sensor pigtail or the harness for contacting the exhaust system.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the appropriate B52 HO2S heater ON and OFF with a scan tool while observing the B52 HO2S Heater Circuit Test Status parameter. The parameter should display OK or Not Run.
Engine idling at operating temperature, observe the scan tool B52 HO2S Heater parameter. The amperage should be within 0.2-1.5 A.
Engine idling at operating temperature, move the related wiring and connectors while observing the B52 HO2S Heater parameter with a scan tool. The parameter should not change with movement. If movement affects the parameter, repair the appropriate harness or connector.
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.

Ignition OFF, disconnect the harness connector at the appropriate B52 HO2S.
Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal D and ground. If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B52 HO2S heater circuit fuse is open, test all components connected to the fuse and replace as necessary.
Ignition ON, observe the appropriate scan tool HO2S Heater Control Open Circuit Test Status parameter. The parameter should display Malfunction. If not the specified value, test the heater control circuit terminal E for a short to ground, or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Connect a 3 A fused jumper wire between the heater control circuit terminal E and ground. Observe the appropriate scan tool HO2S Heater Control Circuit Low Voltage Test Status parameter. The parameter should transition from OK to Malfunction. If not the specified value, test the heater control circuit terminal E for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
Ignition OFF, connect a 10 A fused jumper wire between the control circuit terminal E and the ignition voltage circuit terminal D.
Engine idling, observe the appropriate HO2S Control Circuit High Voltage Test Status parameter. The parameter should transition from Not Run to Malfunction. If not the specified value, test the control circuit and the ignition voltage circuit for high resistance. If the circuits test normal, replace the K20 ECM.
If all circuits test normal, test or replace the appropriate B52 HO2S.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Heated Oxygen Sensor Replacement - Sensor 1»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Heated Oxygen Sensor Replacement - Sensor 2»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) compares actual airflow based on throttle position (TP) to a calculated airflow based on manifold absolute pressure (MAP) sensor, and mass air flow (MAF).

DTC P0068

The engine speed is at least 800 RPM.
The ignition voltage is at least 6.0 V.
The throttle actuator control system is not in reduced power mode.
The DTC runs continuously when the above conditions are met.

DTC P1101

DTC P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0116, P0117, P0118, P0128, P0335, or P0336 is not set
The engine speed is between 575-6, 600 RPM
The engine coolant temperature (ECT) is between -7 to +125°C (+19 to +257°F).
The intake air temperature (IAT) is between -20 to +125°C (-4 to +257°F).
The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTCs

The ECM detects that the actual airflow rate is greater than the calculated airflow.

Action Taken When the DTCs Set

DTC P0068 is a type A DTC.
DTC P1101 is a type B DTC.

Conditions for Clearing the DTCs

DTC P0068 is a type A DTC.
DTC P1101 is a type B DTC.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

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 B75C multifunction intake air sensor is installed correctly. Restricted air filter The Q38 throttle body for dirt, debris, and coking. Also, throttle body blade or shaft damage. Refer to «Throttle Body Cleaning»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__throttle-body-cleaning) for further diagnosis. A damaged Q38 throttle body blade or shaft Splits, kinks, or improper connections at the vacuum hoses Missing, restricted, or leaking exhaust components-Refer to «Restricted Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__restricted-exhaust) . Vacuum leaks at the intake manifold and Q38 throttle body. If a condition exists, repair as necessary.
Ignition ON, observe the diagnostic trouble code (DTC) information with a scan tool. Verify that DTC P0641, P0651, P0697, or P06A3 is not set. If any of the above DTCs are set, refer to «DTC P0641, P0651, P0697, or P06A3 (ECM)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) for further diagnosis.
Determine the current vehicle testing altitude. Compare the MAP Sensor pressure parameter to the reading in the «Altitude Versus Barometric Pressure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__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 «DTC P0106»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) for further diagnosis.
Engine idling, observe the MAP Sensor kPa parameter. The reading should be between 26-52 kPa (3.8-7.5 psi). If not within the specified range, refer to «DTC P0106»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) for further diagnosis.
Engine idling, observe the scan tool MAF Sensor parameter. The reading should be between 2.5-5.5 g/s depending on the engine coolant temperature (ECT) and barometric (BARO) pressure. If not within the specified range, refer to «DTC P0101»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) for further diagnosis.
Use the scan tool snapshot function to take a snapshot of the engine data list while performing the actions listed below. Engine idling Increase the engine speed slowly to 3, 000 RPM and then back to idle. Exit from the scan tool snapshot and review the data. Observe the MAF Sensor g/s 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 parameter does not change smoothly and gradually, refer to «DTC P0101»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) for further diagnosis.
If all conditions test normal, test the engine for a mechanical condition. Refer to «Symptoms - Engine Mechanical»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l) for further diagnosis.

Perform the Diagnostic Repair Verification after completing the repair.

«Air Cleaner Element Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Throttle Body Assembly Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The fuel rail pressure sensor detects fuel pressure within the fuel rail. The engine control module (ECM) provides a 5 V reference voltage on the 5 V reference circuit and ground on the low reference circuit. The ECM receives a varying signal voltage on the signal circuit.

High pressure fuel is regulated by the high pressure fuel pump actuator, which is a part of the high pressure fuel pump. The high pressure fuel pump actuator is a solenoid valve. The ECM provides a voltage on the actuator high control circuit and ground on the actuator low control circuit. Both circuits are controlled through output drivers within the ECM. When deactivated, both drivers are disabled. When activated, the high control circuit driver energizes the high pressure fuel pump actuator and the low control circuit driver pulse-width modulates (PWM) the low control circuit to ground.

The high pressure mechanical fuel pump is driven by three lobes on the camshaft. The ECM uses the camshaft and crankshaft position sensor inputs to synchronize the high pressure fuel pump actuator with the position of each of the camshaft lobes. The ECM regulates fuel pressure by adjusting the portion of each pump stroke that provides fuel to the rail.

The ECM monitors the fuel rail fuel pressure sensor and the high pressure fuel pump actuator to determine if the commanded and actual pressure are within a predetermined range, or if the amount of fuel pressure correction exceeds a calibrated pressure.

P0089, P228C, or P228D

DTC P0016, P0017, P0090, P0091, P0092, P00C8, P00C9, P00CA, P0112, P0113, P0116, P0117, P0118, P0128, P0192, P0193, P0335, P0336, P0340, P0341, P0365, P0366, P0627, P0628, P0629 or P1682 is not set.
The ignition voltage is more than 11 V.
The engine is running.
The low side fuel pressure is more than 275 kPa (40 psi).
The DTC runs continuously when the above conditions are met for 60 s.

P00C6

DTC P0016, P0017, P0090, P0091, P0092, P00C8, P00C9, P00CA, P0112, P0113, P0116, P0117, P0118, P0128, P0192, P0193, P0335, P0336, P0340, P0341, P0365, P0366, P0627, P0628, P0629 or P1682 is not set.
The ignition voltage is more than 8 V.
The engine coolant temperature is between -100 and +80°C (-148 and +176°F).
The low side fuel pressure is more than 300 kPa (43.5 psi).
The engine is not running.
The DTC runs once for each engine start.

P0089

The high pressure fuel pump actuator command is greater than or equal to 240 ° or less than or equal to 0 °. The condition exists for greater than 5 s.

P00C6

The ECM detects that the fuel pressure is not rising or has fallen beyond acceptable limits during engine cranking.

P228C

The actual fuel rail pressure is 3 MPa (435 psi) less than the desired fuel pressure. The condition exists for greater than 5 s.

P228D

The actual fuel rail pressure is 3 MPa (435 psi) greater than the desired fuel rail pressure. The condition exists for greater than 5 s.

DTCs P0089 and P00C6 are Type B DTCs.
DTCs P228C and P228D are Type A DTCs.
A message center or an indicator displays Reduced Engine Power.
Scan tool control of the high pressure fuel pump is inhibited.

DTCs P0089 and P00C6 are Type B DTCs.
DTCs P228C and P228D are Type A DTCs.

A restricted fuel feed pipe between the fuel feed pipe fuel pressure sensor and the high pressure fuel pump may set a DTC.
A condition with the fuel tank fuel pump module or the fuel pump flow control module may set a DTC.
A skewed fuel rail pressure sensor, or an intermittent condition in the fuel rail pressure sensor circuits may set a DTC.
A leaking or restricted fuel injector may set a DTC.
A short to voltage in the crankshaft position signal circuit may set a DTC.
A short to voltage in the camshaft position actuator solenoid valve control circuit may set a DTC.

Schematic Reference

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Observe the DTC information with a scan tool. DTC P0627, P0628, P0629, P069E, or U0109 should not set. If a DTC is set refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Attempt to start and idle the engine.
Observe the DTC information with a scan tool. DTCs P0089, P00C6, P228C, and P228D should not set.
Engine idling, observe the Fuel Rail Pressure Sensor parameter with a scan tool. The pressure should be approximately 2.96-3.24 Mpa (429-470 psi).
Command an increase and decrease in Fuel Pressure with a scan tool. Observe the scan tool Fuel Rail Pressure Sensor parameter. The Fuel Rail Pressure Sensor should increase or decrease with each commanded state.
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.

Ignition ON, observe the scan tool Fuel Pump Control Module Fuel Pressure Sensor parameter. Command an increase in Fuel Pressure with a scan tool. Verify the scan tool Fuel Pressure Sensor parameter increases to greater than 414 kPa (60 psi) as commanded. If less than the specified range, refer to «Fuel System Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
Remove the G18 high pressure fuel pump and visually inspect the lobes on the camshaft for unusual wear. If the lobes appear normal, replace the G18 high pressure fuel pump. If the lobes are worn, replace the camshaft.

Static Test

Ignition OFF, disconnect the harness connector at the G18 high pressure fuel pump.
Test for 10 ohms plus/minus 1 ohms at 25°C (77°F) between the low control circuit terminal 1 and the high control circuit terminal 2. If not within the specified range, replace the G18 high pressure fuel pump.
Test for infinite resistance between each terminal and the G18 high pressure fuel pump housing. If not the specified value, replace the G18 high pressure fuel pump.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Fuel Pump Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__fuel-pump-replacement)
«Intake Camshaft and Valve Lifter Replacement»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l)

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
High Pressure Fuel Pump Actuator High Control	P0091, P00C9	P0090, P00C8	P0092, P00CA, P0690
High Pressure Fuel Pump Actuator Low Control	P0091, P00C9	P0090, P00C8	P0092, P00CA, P0690

High pressure fuel is regulated by the high pressure fuel pump actuator, which is a part of the high pressure fuel pump. The high pressure fuel pump actuator is a solenoid valve. The ECM provides battery voltage on the actuator high control circuit and ground on the actuator low control circuit. Both circuits are controlled through output drivers within the ECM. When deactivated, both drivers are disabled. When activated, the high control circuit driver energizes the high pressure fuel pump actuator and the low control circuit driver pulse-width modulates (PWM) the low control circuit to ground. The ECM monitors the voltage on the circuits to detect a failure.

The ignition voltage is greater than 11 V.
The engine speed is greater than 50 RPM.
The DTCs run continuously within the enabling conditions.

P0090

The ECM detects an open circuit in the high pressure fuel pump actuator low control circuit.
The DTC sets when the above condition is present for 4 s.

P0091

The ECM detects a short to ground in the high pressure fuel pump actuator low control circuit.
The DTC sets when the above condition is present for 4 s.

P0092

The ECM detects a short to voltage in the high pressure fuel pump actuator low control circuit.
The DTC sets when the above condition is present for 4 s.

P00C8

The ECM detects an open circuit in the high pressure fuel pump actuator high control circuit.
The DTC sets when the above condition is present for 4 s.

P00C9

The ECM detects a short to ground in the high pressure fuel pump actuator high control circuit.
The DTC sets when the above condition is present for 4 s.

P00CA

The ECM detects a short to voltage in the high pressure fuel pump actuator high control circuit.
The DTC sets when the above condition is present for 4 s.

DTCs P0090, P0091, P0092, P00C8, P00C9, and P00CA are Type A DTCs.
A message center or an indicator displays Reduced Engine Power.

DTCs P0090, P0091, P0092, P00C8, P00C9, and P00CA are Type A DTCs.

Schematic Reference

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Observe the DTC information with a scan tool. DTC P0090, P0091, P0092, P00C8, P00C9, P00CA, P0685, or P1682 should not set. If a DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for further diagnosis.
Ignition ON, command the Fuel Pressure Regulator ON and OFF with a scan tool while observing the following control circuit status parameters: Fuel Pressure Regulator Control Circuit High Voltage Test Status Fuel Pressure Regulator Control Circuit Open Test Status Fuel Pressure Regulator Control Circuit Low Voltage Test Status Fuel Pressure Regulator High Control Circuit High Voltage Test Status Fuel Pressure Regulator High Control Circuit Open Test Status Fuel Pressure Regulator High Control Circuit Low Voltage Test Status Each parameter should toggle between OK and Not Run or Not Run and OK.
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.

Ignition OFF, disconnect the harness connector at the G18 high pressure fuel pump.
Ignition ON, verify that a test lamp does not illuminate between the high control circuit terminal 2 and ground and the low control circuit terminal 1 and ground. If the test lamp illuminates, test the appropriate control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Verify that a test lamp does not illuminate between the high control circuit terminal 2 and B+ and the low control circuit terminal 1 and B+. If the test lamp illuminates, test the appropriate control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
Connect a 3 A fused jumper wire between the high control circuit terminal 2 and ground. The Fuel Pressure Regulator High Control Circuit Open Test Status should transition from Malfunction to OK and the Fuel Pressure Regulator High Control Circuit Low Voltage Test Status should transition from OK to Malfunction. If not the specified value, test the high control circuit for an open/high resistance.
Connect a 3 A fused jumper wire between the low control circuit terminal 1 and B+. The Fuel Pressure Regulator Control Circuit Open Test Status should transition from Malfunction to OK and the Fuel Pressure Regulator Control Circuit High Voltage Test Status should transition from OK to Malfunction. If not the specified value, test the low control circuit for an open/high resistance.
If all circuits test normal, test or replace the G18 high pressure fuel pump.

Static Test

Ignition OFF, disconnect the harness connector at the G18 high pressure fuel pump.
Test for 9-11 ohms at 25°C (77°F) between the low control circuit terminal 1 and the high control circuit terminal 2 at the G18 high pressure fuel pump. If not within the specified range, replace the G18 high pressure fuel pump.
Measure the resistance between each terminal and the high pressure fuel pump housing. The DMM should display OL. If less than the specified value, replace the G18 high pressure fuel pump.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Fuel Pump Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__fuel-pump-replacement)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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	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

MAF Sensor

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 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.

Conditions for Running the DTCs

DTCs P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0116, P0117, P0118, P0128, P0335 or P0336 are not set.
The engine speed is between 400-6, 600 RPM.
The engine coolant temperature (ECT) is between -7 and +125°C (+19 and +257°F).
The intake air temperature (IAT) is between -20 and +125°C (-4 and +257°F).
The DTC runs continuously when the above conditions are met.

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.

DTC P0101 is a Type B DTC.

A steady or intermittent high resistance of 15 ohms or greater on the ignition voltage circuit will cause the MAF sensor signal to be increased by as much as 60 g/s.
Resistance in the MAF signal circuit may cause this DTC to set.
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 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.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 38522 Variable Signal Generator

For equivalent regional tools, refer to the appropriate regional parts catalog.

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) If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Verify that restrictions do not exist in the exhaust system. Refer to «Restricted Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__restricted-exhaust) .
Engine idling, observe the scan tool MAF Sensor parameter. The reading should be between 2.2-5.5 g/s depending on the engine coolant temperature (ECT) and barometric (BARO) pressure.
Verify the scan tool MAF Sensor g/s parameter changes smoothly and gradually as the engine speed is increased and decreased while performing the actions listed below. Engine idling Perform the scan tool snapshot function. Increase the engine speed slowly to 3, 000 RPM and then back to idle. Exit from the scan tool snapshot and review the data. Observe the MAF Sensor parameter frame by frame with a scan tool.
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 (Engine Coolant Temperature Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-engine-coolant-temperature) .
Verify the proper operation of the MAP sensor. A skewed MAP sensor will cause the BARO value to be inaccurate. Refer to «DTC P0106»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) for further diagnosis.
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.

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 mass air flow/intake air temperature sensor element for contamination.
Ignition OFF, disconnect the harness connector at the B75B mass air flow /intake air temperature sensor.
Ignition OFF, all vehicle systems OFF, this may take up to 2 min, test for less than 5 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal C and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the fuse is open, test all the components connected to the circuit and repair or replace as necessary.
Ignition ON, test for 4.8-5.2 V between the signal circuit terminal A and ground. 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 engine control module. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
Ignition OFF, connect the red lead of the J 38522 variable signal generator to the signal circuit terminal A at the harness connector. Connect the battery voltage supply to B+, and the black lead to ground.
Set the J 38522 variable signal generator to the following specifications. Signal switch to 5 V Duty Cycle switch to 50 % (Normal) Frequency switch to 5 KHz
Engine idling, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 4, 950-5, 050 Hz. If the parameter is not within the specified range and the signal circuit tests OK, replace the K20 engine control module.
If all other circuits test normal, test or replace the B75B mass air flow /intake air temperature sensor.

Perform the Diagnostic Repair Verification after completing the repair.

«Engine Coolant Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) for mass air flow /intake air temperature sensor replacement
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming, and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
Ignition 1 Voltage	P0030, P0036, P0102, P0135, P0141, P0443	P0101	P0102	P0690	P0101, P0103
MAF Sensor Signal	P0102	P0102	P0102	P0102	P0101, P0103, P1101
Ground		P0102	P0102		P0102

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

MAF Sensor

The mass air flow (MAF) sensor is integrated with the intake air temperature (IAT) sensor. The MAF sensor is an air flow meter that measures the amount of air in the sensor bore. The engine control module (ECM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition.

The ECM applies 5 V to the MAF sensor on the MAF sensor signal circuit. The sensor uses the voltage to produce a variable frequency signal based on the inlet air flow through the sensor bore. The signal varies with engine load and is displayed by the scan tool as Hertz (Hz) and grams per second (g/s). Ignition voltage and ground circuits are also supplied to the MAF sensor's internal circuits for these sensors.

The engine is running for at least 1 s.
The engine speed is at least 300 RPM.
The ignition signal is at least 11 V.
The above conditions are met for at least 1 s.
The DTC runs continuously when the above conditions are met.

P0102

The ECM detects that the MAF Sensor signal parameter is less than 500 Hz (about 0.25 g/s) for at least 250 cylinder firing events.

P0103

The ECM detects that the MAF Sensor signal parameter is at least 11, 000 Hz (about 328 g/s) for at least 250 cylinder firing events.

DTCs P0102 and P0103 are Type B DTCs.

Conditions for Clearing the MIL/DTCs

DTCs P0102 and P0103 are Type B DTCs.

Verify the integrity of the air induction system by inspecting for the following conditions: Loose or improper installation Damaged components Any water intrusion in the induction system Any contamination or debris on the sensing elements of the MAF sensor
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.
Resistance in the MAF signal circuit may cause this DTC to set.
Depending on the current ambient temperature, and the vehicle operating conditions, a MAF sensor signal circuit that is shorted to the IAT sensor 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.
Verify that any electrical aftermarket devices are properly connected and grounded. Refer to «Checking Aftermarket Accessories»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__checking-aftermarket-accessories) .

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 38522 Variable Signal Generator

For equivalent regional tools, refer to the appropriate regional parts catalog.

Verify that the following DTCs are not set: P0685, P0690 or B1380. If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Engine idling, observe the scan tool MAF Sensor parameter. The reading should be between 2.2-5.5 g/s depending on the engine coolant temperature (ECT) and barometric (BARO) pressure.
Verify the scan tool MAF Sensor g/s parameter changes smoothly and gradually as the engine speed is increased and decreased while performing the actions listed below. Engine idling Perform the scan tool snapshot function. Increase the engine speed slowly to 3, 000 RPM and then back to idle. Exit from the scan tool snapshot and review the data. Observe the MAF Sensor parameter frame by frame with a scan tool.
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.

Ignition OFF, disconnect the harness connector at the B75B mass air flow/intake air temperature sensor.
Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal C and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the fuse is open, test all the components connected to the circuit and repair or replace as necessary.
Ignition ON, test for 4.8-5.2 V between the signal circuit terminal A and ground. 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 engine control module. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
Ignition OFF, connect the red lead of the J 38522 variable signal generator to the signal circuit terminal A at the harness connector. Connect the battery voltage supply to B+, and the black lead to ground.
Set the J 38522 variable signal generator to the following specifications. Signal switch to 5 V Duty Cycle switch to 50 % (Normal) Frequency switch to 5 KHz
Engine idling, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 4, 950-5, 050 Hz. If the parameter is not within the specified range and the signal circuit is OK, replace the K20 engine control module.
If all other circuits test normal, replace the B75B mass air flow/intake air temperature sensor.

Perform the Diagnostic Repair Verification after completing the repair.

«Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) for mass air flow/intake air temperature sensor replacement
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming, and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
5 V Reference	P0107, P0452, P0532, P0641	P0106, P0107	P0107	P0108, P0533, P0641	P0106, P0107
MAP Sensor Signal	P0107	P0106, P0107	P0107	P0106, P0108	P0106, P0107, P1101
Low Reference		P0106, P0108	P0106, P0108		P0106, P0108

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running, transmission in Park or Neutral Parameter Normal Range: 20-48 kPa, varies with altitude
5 V Reference	0 kPa (0 psi)	0 kPa (0 psi)	127 kPa (1.5 psi)
MAP Sensor Signal	0 kPa (0 psi)	0 kPa (0 psi)	127 kPa (1.5 psi)
Low Reference		127 kPa (1.5 psi)

MAP Sensor

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 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 Performance Test parameter.

MAF Performance Test	MAP Performance Test 1	MAP Performance Test 2	Throttle Position 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

Scan Tool Diagnostic Test Results

DTC P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0335, or P0336 is 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.

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

DTC P0106 is a Type B DTC.

A wide open throttle (WOT) acceleration from a stop should cause the MAP sensor parameter on the scan tool to increase rapidly to near the BARO parameter at the time of the 1-2 shift.
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.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 23738-A Mityvac
J 35555 Metal Mityvac
For equivalent regional tools, refer to the appropriate regional parts catalog.

Verify that DTC P0697 is not set. If the DTC is set, refer to «DTC P0641, P0651, P0697, or P06A3 (ECM)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
Verify that restrictions do not exist in the exhaust system. Refer to «Restricted Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__restricted-exhaust) .
Ignition OFF for 90 s, determine the current vehicle testing altitude.
Ignition ON, engine OFF, observe the scan tool BARO parameter. Compare the parameter to the «Altitude Versus Barometric Pressure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__altitude-versus-barometric-pressure) table. The BARO parameter should be within the specified range indicated in the table.
Use the scan tool and compare the MAP Sensor parameter to a known good vehicle, under various operating conditions. The reading should be within 5 kPa of the known good vehicle.
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.

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 Improperly routed vacuum hoses In cold climates, inspect for any snow or ice buildup Verify that restrictions do not exist in the MAP sensor port or vacuum source.
Ignition OFF for 90 s, disconnect the harness connector at the B74 MAP sensor.
Ignition OFF, test for less than 5 ohms between the low reference circuit terminal 2 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 K20 ECM.
Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Verify the scan tool MAP Sensor parameter is less than 1 kPa (0.1 psi). If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Install a 3 A fused jumper wire between the signal circuit terminal 3 and the 5 V reference circuit terminal 1. Verify the scan tool MAP Sensor parameter is greater than 127 kPa (1.5 psi). 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.
If the circuits test normal, test or replace the B74 MAP sensor.

Note. You must perform the Circuit/System Testing in order to verify the integrity of the MAP sensor circuits before proceeding with the Component Testing.

Skewed Signal Test

Using the following steps and referencing the table below will determine if the MAP sensor is skewed.
Ignition ON, engine OFF, observe the MAP Sensor scan tool parameter.
Use the observed MAP Sensor scan tool parameter that is closest to a value that is indicated in the first column. THEN
Using the J 23738-A Mityvac or the J 35555 Metal Mityvac to apply 5 in Hg of vacuum to the B74 MAP sensor, the parameter in the first column should decrease by 17 kPa (2.5 psi). The acceptable range is indicated in the second column.
Using the J 23738-A Mityvac or the J 35555 Metal Mityvac to apply 10 in Hg of vacuum to the B74 MAP sensor, the parameter in the first column should decrease by 34 kPa (4.7 psi). The acceptable range is indicated in the third column.

Ignition ON, Engine OFF, MAP Sensor Parameter	MAP Sensor Parameter With 5 Inches of Vacuum Applied	MAP Sensor Parameter With 10 Inches of Vacuum Applied
100 kPa	79-87 kPa (11.5-12.6 psi)	62-70 kPa (9-10.2 psi)
95 kPa	74-82 kPa (10.7-11.9 psi)	57-65 kPa (8.3-9.4 psi)
90 kPa	69-77 kPa (10-11.2 psi)	52-60 kPa (7.5-8.7 psi)
80 kPa	59-67 kPa (8.6-9.7 psi)	42-50 kPa (6.1-7.3 psi)
70 kPa	49-57 kPa (7.1-8.3 psi)	32-40 kPa (4.6-5.8 psi)
60 kPa	39-47 kPa (5.7-6.8 psi)	22-30 kPa (3.2-4.4 psi)

Erratic Signal Test

Ignition OFF, remove the B74 MAP sensor.
Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 and the corresponding terminal of the B74 MAP sensor.
Install a jumper wire between the low reference circuit terminal 2 of the B74 MAP sensor and ground.
Install a jumper wire at terminal 3 of the B74 MAP sensor.
Connect a DMM between the jumper wire from terminal 3 of the B74 MAP sensor and ground.
Ignition ON, with the J 23738-A Mityvac or J 35555 Metal Mityvac, slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary between 0-5.2 V, without any spikes or dropouts. If the voltage reading is erratic, replace the B74 MAP sensor.

Perform the Diagnostic Repair Verification after completing the repair.

«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, programming, and setup.
«Manifold Absolute Pressure Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
5 V Reference	P0108, P0697	P0106, P0107	P0107	P0607	P0106, P0107
MAP Sensor Signal	P0107	P0106, P0107	P0107	P0106	P0106, P0107, P1101
Low Reference		P0106, P0108	P0106, P0108		P0106, P0108

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running, transmission in Park or Neutral Parameter Normal Range: 20-48 kPa, varies with altitude
5 V Reference	0 kPa (0 psi)	0 kPa (0 psi)	127 kPa (1.5 psi)
MAP Sensor Signal	0 kPa (0 psi)	0 kPa (0 psi)	127 kPa (1.5 psi)
Low Reference		127 kPa (1.5 psi)

MAP Sensor

The manifold absolute pressure (MAP) sensor has a 5 V reference circuit, a low reference circuit, and a signal circuit. The engine control module (ECM) supplies 5 V to the MAP sensor on the 5 V reference circuit, and provides a ground for the low reference circuit. The MAP sensor provides a voltage signal to the ECM on the signal circuit relative to the intake manifold pressure changes.

DTC P0697 is not set.
The engine is running.
This DTC runs continuously within the enabling conditions.

P0107

The ECM detects that the MAP sensor voltage is less than 0.20 V for more than 5 s.

P0108

The ECM detects that the MAP sensor voltage is more than 4.80 V for more than 5 s.

DTCs P0107 and P0108 are Type B DTCs.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 23738-A Mityvac
J 35555 Metal Mityvac
For equivalent regional tools, refer to the appropriate regional parts catalog.

Verify that DTC P0697 is not set. If the DTC is set, refer to «DTC P0641, P0651, P0697, or P06A3 (ECM)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
Ignition ON, observe the scan tool MAP Sensor parameter. The reading should be between 0.20-4.80 V.
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.

Ignition OFF, disconnect the harness connector at the B74 MAP sensor.
Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 ohms between the low reference circuit terminal 2 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 K20 ECM.
Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Verify the scan tool MAP Sensor parameter is less than 1 kPa (0 psi). If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Install a 3 A fused jumper wire between the signal circuit terminal 3 and the 5 V reference circuit terminal 1. Verify the scan tool MAP Sensor parameter is greater than 127 kPa (1.5 psi). 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.
If the circuits test normal, test or replace the B74 MAP sensor.

Note. You must perform the Circuit/System Testing in order to verify the integrity of the MAP sensor circuits before proceeding with the Component Testing.

Erratic Signal Test

Ignition OFF, remove the B74 MAP sensor.
Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 and the corresponding terminal of the B74 MAP sensor.
Install a jumper wire between the low reference circuit terminal 2 of the B74 MAP sensor and ground.
Install a jumper wire at terminal 3 of the B74 MAP sensor.
Connect a DMM between the jumper wire from terminal 3 of the B74 MAP sensor and ground.
Ignition ON, with the J 23738-A Mityvac or the J 35555 Metal Mityvac, slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary between 0-5 V without any spikes or dropouts. If the voltage reading is erratic, replace the B74 MAP sensor.

Perform the Diagnostic Repair Verification after completing the repair.

«Manifold Absolute Pressure Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, programming, and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
IAT Sensor Signal	P0112, P0114	P0111, P0113, P0114	P0113*, P0114	P0111
Low Reference		P0111, P0113, P0114	P0113*, P0114
*Internal ECM or sensor damage may occur if the circuit is shorted to B+.

IAT Sensor

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running Parameter Normal Range: Varies with ambient temperature
IAT Sensor Signal	150°C (302°F)	40°C (-40°F)	40°C (-40°F)*
Low Reference		40°C (-40°F)	40°C (-40°F)*
*Internal ECM or sensor damage may occur if the circuit is shorted to B+

IAT Sensor

The intake air temperature (IAT) sensor is a variable resistor that measures the temperature of the air in the sensor bore. The IAT is integrated with the mass air flow (MAF) sensor. The engine control module (ECM) supplies 5 V to the IAT sensor signal circuit and a ground for the IAT sensor low reference circuit. The signal varies with inlet air temperature and is displayed by the scan tool as °C (°F).

IAT Sensor	IAT Sensor Resistance	IAT Sensor Signal Voltage
Cold	High	High
Warm	Low	Low

P0112, P0113, and P0114

The ignition is ON, or the engine is running.
The DTCs run continuously when the above conditions are met.

P0112

The ECM detects that the IAT sensor signal is warmer than 149°C (300°F) for at least 5 s.

P0113

The ECM detects that the IAT sensor signal is colder than -60°C (-76°F) for at least 5 s.

Note. The scan tool display range is between -40 and +150°C (-40 and +302°F).

P0114

The ECM detects that the IAT sensor signal is intermittent or has abruptly changed for at least 5 s.

DTCs P0112, P0113, and P0114 are Type B DTCs.
The ECM commands the cooling fans ON.

DTCs P0112, P0113, and P0114 are Type B DTCs.

Certain resistance conditions with IAT or ECT sensors may cause unwarranted cooling fan activation. If the ECM is commanding the cooling fans ON for no apparent reason and without any component or system DTCs set, the IAT or ECT sensor may be skewed. Refer to «Temperature Versus Resistance - Intake Air Temperature Sensor (Hitachi Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-intake-air) , or «Temperature Versus Resistance (Engine Coolant Temperature Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-engine-coolant-temperature) tables, if this condition is suspected.
With the ignition ON, the engine OFF, if the engine is cold, a properly functioning IAT sensor will gradually increase the scan tool IAT Sensor parameter. This is due to the heat that is generated by the MAF sensor heating elements.
Depending on the ambient temperature, an IAT sensor signal circuit or low reference circuit that is shorted to the MAF sensor signal circuit can cause a DTC P0113 and/or P0114 to set. This condition causes a rapid fluctuation in the IAT Sensor parameter.
An IAT sensor signal circuit that is shorted to the MAF sensor ignition circuit can cause a DTC P0113 and/or P0114 to set.
A MAF sensor ground circuit that is open will cause a DTC P0113 and/or a DTC P0114 to set.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Engine running, observe the scan tool IAT Sensor parameter. The reading should be between -40 and +149°C (-40 and +300°F) depending on the current ambient temperature and the vehicle operating conditions.
Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Ignition OFF, disconnect the harness connector at the B75B mass air flow, intake air temperature sensor.
Ignition OFF, all systems OFF. It may take up to for 2 minutes for all vehicle systems to power down. Test for less than 5 ohms 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 K20 engine control module.
Ignition OFF, all vehicle systems OFF, test for less than 5 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
Ignition ON, verify the scan tool IAT Sensor parameter is colder than -39°C (-38°F). If warmer than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 engine control module.
Ignition ON. Test for 4.8-5.2 V between the IAT sensor 1 signal circuit terminal E and ground. 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 engine control module. NOTE: If the signal circuit is shorted to a voltage the ECM or the sensor may be damaged. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
If all circuits test normal, test or replace the B75B mass air flow, intake air temperature sensor.

Ignition OFF, disconnect the harness connector at the B75B mass air flow, intake air temperature sensor.
Test the IAT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the «Temperature Versus Resistance - Intake Air Temperature Sensor (Hitachi Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-intake-air) table. The resistance values should be in range of the table values. If not within the specified range, replace the B75B mass air flow, intake air temperature sensor.

Perform the Diagnostic Repair Verification after completing the repair.

«Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) for Mass Airflow Sensor with Intake Air Temperature Sensor replacement.
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming, and setup.

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
ECT Sensor Signal	P0117, P0119	P0118	P0118	P0116, P0119, P0128
Low Reference		P0118, P0119	P0118	P0119, P0128

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running at various operating conditions Parameter Normal Range: Varies with coolant temperature
ECT Sensor	150°C (302°F)	40°C (-40°F)	40°C (-40°F)
Low Reference		40°C (-40°F)	40°C (-40°F)

ECT Sensor

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 V to the ECT sensor signal circuit and a ground for the low reference circuit.

The ECM uses this high side coolant rationality diagnostic to determine if the input from the ECT sensor is skewed warmer than normal. The internal clock of the ECM will record the amount of time the ignition is OFF. If the calibrated ignition OFF time is met at start-up, the ECM will compare the temperature difference between the ECT and the intake air temperature (IAT) to determine if the temperatures are within an acceptable operating range of each other.

DTC P0112, P0113, P0117, P0118, P0128, P0502, P0503, P0601, P1621, or P2610 is not set.
The vehicle has had a minimum ignition OFF time of 7 h.
The ignition is ON.
The start-up IAT is warmer than -7°C (+19°F).
Propulsion system OFF time greater than 0 s.
The Fuel Level Sensor parameter is greater than 2.5%.
This DTC runs once per ignition cycle within the enabling conditions.

The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 30°C (54°F) warmer than the IAT sensor. OR
The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 16°C (29°F) warmer than the IAT sensor, and a block heater has not been detected. OR
The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 16°C (29°F) warmer than the IAT sensor. And the time spent cranking the engine without starting is greater than 10 s. Then the vehicle must be driven for greater than 7 min and at greater than 24 km/h (15 mph). If the IAT sensor then decreases greater than 5°C (9°F), an engine block heater was detected and the test is aborted. If the IAT sensor does not decrease, an engine block heater was not detected DTC P0116 will set.

DTC P0116 is a Type B DTC.

An IAT sensor that is skewed colder at various ambient temperatures due to greater resistance than is normal will increase the range between these two sensors. Measure and record the resistance of the IAT sensor at various ambient temperatures, then compare those measurements to the «Temperature Versus Resistance (Engine Coolant Temperature Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-engine-coolant-temperature) table.
A slight to moderate resistance in the IAT sensor signal circuit or low reference circuit will increase the range between these two sensors. This condition results in a greater voltage on the IAT sensor signal circuit, which is interpreted by the ECM as a colder IAT.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition OFF, inspect the cooling system surge tank for the proper coolant level. Refer to «Cooling System Leak Testing»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-leak-testing) , and «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-ge) .
Ignition OFF for 7 h or greater.
Ignition ON, observe the scan tool ECT Sensor and IAT Sensor parameters. The ECT, IAT, and ambient temperature should be within 15°C (27°F) of each other.
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.

Ignition OFF and all vehicle systems OFF, disconnect the B34 engine coolant temperature sensor harness connector at the sensor. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohms between the low reference circuit terminal A 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 K20 engine control module.
Ignition ON, verify the scan tool ECT Sensor parameter is colder than -39°C (-38°F). If warmer than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the K20 engine control module.
Install a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT Sensor parameter is warmer than 149°C (300°F). If colder than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
If the circuits test normal, test or replace the B34 engine coolant temperature sensor.

Static Test

Ignition off, remove the B34 engine coolant temperature sensor.
Test the B34 engine coolant temperature sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the «Temperature Versus Resistance (Engine Coolant Temperature Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-engine-coolant-temperature) table and verify that the resistance is within 5% of the specification. If not within the specified range, replace the B34 engine coolant temperature sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Engine Coolant Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, programming and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
ECT Sensor Signal	P0117	P0118	P0118	P0116, P0128
Low Reference		P0118	P0118	P0128
*ECM or sensor damage may occur if the circuit is shorted to B+.

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running at various operating conditions Parameter Normal Range: Varies with coolant temperature
Signal	140°C (284°F)	40°C (-40°F)	40°C (-40°F)
Low Reference		40°C (-40°F)	40°C (-40°F)

ECT Sensor

The purpose of this diagnostic is to determine if the input from the ECT sensor is skewed warmer than normal. The internal clock of the ECM will record the amount of time the engine is OFF. If the required engine OFF time is met at start-up, the ECM will compare the temperature difference between the actual measured ECT and IAT sensors.

P0117

The ignition is ON. OR
The engine is running for greater than 10 s. OR
The engine run time is less than 10 s when the intake air temperature (IAT) is colder than 50°C (122°F).
This DTC runs continuously within the enabling conditions.

P0118

The ignition is ON. OR
The engine is running for greater than 10 s. OR
The engine run time is less than 10 s when the IAT is warmer than 0°C (32°F).
This DTC runs continuously within the enabling conditions.

P0117

The ECM detects that the ECT is warmer than 149°C (300°F) for greater than 5 s.

P0118

The ECM detects that the ECT is colder than -39°C (-38°F) for greater than 5 s.

DTC P0117 or P0118 are a Type B DTC.
The cooling fans will be commanded ON.
The Engine Coolant Temperature Gauge is inoperative.

DTC P0117 or P0118 are a Type B DTC.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON.
Verify the scan tool ECT Sensor parameter is between -39 to + 120°C (-38 to +248°F) and changes with engine run time. If not between -39 to + 120°C (-38 to +248°F) or does not change Refer to Circuit/System Testing below. If between -39 to + 120°C (-38 to +248°F) and changes
All OK.

Ignition OFF and all vehicle systems OFF, disconnect the B34 engine coolant temperature sensor harness connector at the sensor. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 5 ohms between the low reference circuit terminal A and ground. If 5 ohms or greater Ignition OFF, disconnect the harness connector at the K20 engine control module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 engine control module. If less than 5 ohms
Ignition ON.
Verify the scan tool ECT Sensor parameter is colder than -39°C (-38°F). If warmer than -39°C (-38°F) Ignition OFF, disconnect the harness connector at the K20 engine control module. Test for infinite resistance between the signal circuit terminal B and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 engine control module. If colder than -39°C (-38°F)
Install a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A.
Verify the scan tool ECT sensor parameter is warmer than 149°C (300°F). If colder than the 149°C (300°F) Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Ignition OFF Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 engine control module. If warmer than 149°C (300°F)
Test or replace the B34 engine coolant temperature sensor.

Ignition OFF, remove the B34 engine coolant temperature sensor.
.Test the B34 engine coolant temperature sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the «Temperature Versus Resistance (Engine Coolant Temperature Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-engine-coolant-temperature) table and verify that the resistance is within 5% of the specification. If not within the specified range Replace the B34 engine coolant temperature sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Engine Coolant Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) engine control module replacement, programming, and setup.

Repair Verification

Ignition ON, observe the ECT Sensor parameter. The reading should be between -39 to + 120°C (-38 to +248°F).
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.
Verify a DTC does not set. If any DTC sets Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for further diagnosis. If no DTC sets
All OK

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
ECT Sensor Signal	P0117, P0119	P0116, P0118, P0119	P0118*	P0116, P0128
Low Reference		P0116, P0118, P0119	P0118*	P0128
* Internal ECM or sensor damage may occur if the circuit is shorted to B+

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine operating in Closed Loop Parameter Normal Range: -39 to +142°C (-38 to +288°F) Varies with coolant temperature.
ECT Sensor Signal	143°C (289°F)	40°C (-40°F)	40°C (-40°F)*
Low Reference		40°C (-40°F)	40°C (-40°F)*
* Internal ECM or ECT sensor damage may occur if the circuit is shorted to B+

ECT Sensor

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and supplies a ground to the low reference circuit. The ECM monitors the performance of the ECT sensor. If the ECM detects excessive noise or rapid fluctuations in the ECT signal, this DTC sets.

The following table illustrates the difference between temperature, resistance, and voltage

ECT	ECT Resistance	ECT Signal Voltage
Cold	High	High
Warm	Low	Low

DTC P0117 or P0118 is not set.
The ignition is ON or the engine is operating.
DTC P0119 runs continuously once the above conditions are met.

The ECM detects that the ECT changed ±5°C (±9°F) greater than the expected value during a calibrated amount of time.
The condition exists for approximately 1 minute.

DTC P0119 is a Type B DTC.

Test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a DTC or a driveability condition. Refer to «Temperature Versus Resistance (Engine Coolant Temperature Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-engine-coolant-temperature) .
If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F).
After starting a cold engine, the ECT sensor temperature should rise steadily, then stabilize after the thermostat opens.
High resistance on either the ECT sensor signal circuit or the ECT sensor low reference circuit could set a DTC.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Observe the scan tool engine coolant temperature (ECT) sensor parameter, while moving the ECT sensor connector and the K20 ECM connector. The ECT sensor parameter should not fluctuate while moving the related harnesses and connectors. Repair the suspected harness or connection if the ECT parameter fluctuates greater than 3°C (5°F) while moving the related harnesses and connectors.
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.

Ignition OFF, disconnect the harness connector at the B34 engine coolant temperature sensor.
Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 ohms between the low reference circuit terminal A 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 K20 engine control module.
Ignition ON, verify the scan tool ECT Sensor parameter is colder than -40°C (-40°F). If warmer than the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 engine control module.
Install a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT Sensor parameter is warmer than 150°C (302°F). If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
If all circuits test normal, test or replace the B34 engine coolant temperature sensor.

Ignition OFF, disconnect the harness connector at the B34 engine coolant temperature sensor.
Test the ECT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the «Temperature Versus Resistance (Engine Coolant Temperature Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-engine-coolant-temperature) table and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the B34 engine coolant temperature sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Engine Coolant Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5 V Reference	P06A3	P0122, P0222, P16A0	P06A3	P0121, P16A2, P2135
Throttle Position Sensor Signal	P0122, P0222, P16A0	P0122, P0222, P16A1	P0123, P0223, P16A0, P16A1, P16A2**	P0121, P16A2, P2135
Low Reference		P0123, P0223, P16A1		P0121, P16A2, P2135
* This DTC set indicates an internal throttle body condition. ** A short to voltage causes P16A1 to set. If DTC P16A0, P16A1, and P16A2 set at the same time, an intermittent circuit condition exists.

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The engine is operating with the throttle closed. All accessories OFF. Parameter Normal Range: Throttle Position Sensor 1 3.75-4.75 V
5 V Reference	0.0 V	5.0 V	5.0 V
Throttle Position Sensor Signal	0.0 V	0.0 V	0.0 V
Low Reference		0.0 V

Throttle Position Sensor 1

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The engine is operating with the throttle closed. All accessories OFF. Parameter Normal Range: Throttle Position Sensor 2 0.45-0.90 V
5 V Reference	0.0 V	0.0 V	0.0 V
Throttle Position Sensor Signal	5.0 V	5.0 V	5.0 V
Low Reference		5.0 V

Throttle Position Sensor 2

The throttle body assembly contains a contact-less inductive throttle position sensing element that is managed by a customized integrated circuit. The throttle position sensor is mounted within the throttle body assembly and is not serviceable. The engine control module (ECM) supplies the throttle body with a 5 V reference circuit, a low reference circuit, an H-bridge motor directional control circuit, and an asynchronous signal/serial data circuit. The asynchronous signal means communication is only going from the throttle body to the ECM. The throttle body cannot receive data from the ECM over the signal/serial data circuit. The throttle position sensor provides a signal voltage that changes relative to throttle blade angle. The customized integrated circuit translates the voltage based position information into serial data using the Society of Automotive Engineers (SAE) J2716 Single Edge Nibble Transmission (SENT) protocol. The throttle position sensor information is transmitted between the throttle body and the ECM on the signal/serial data circuit. The ECM decodes the serial data signal and is used as voltages for throttle position sensor 1 and 2.

P0121

DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0335, or P0336 is not set.
The engine speed is between 400-6, 200 RPM.
The engine coolant temperature (ECT) is between -7 to +125°C (19-257°F).
The intake air temperature (IAT) is between -20 to +125°C (-4 to +257°F).
The DTC runs continuously when the above conditions are met.

P0122, P0123, P0222, P0223

DTC P06A3 is not set.
The ignition is ON or the engine is running.
The run/crank or powertrain relay voltage is greater than 6.0 V and reduced power is not active.
The DTCs run continuously when the above condition are met.

P16A0, P16A1, or P16A2

The ignition is ON or the engine is operating.
The run/crank voltage is greater than 6.4 V.
The DTCs run continuously once the above conditions are met for greater than 1 s.

P2135

DTCs P0122, P0123, P0222, P0223, or P06A3 are not set.
The ignition is ON or the engine is running.
The run/crank or powertrain relay voltage is greater than 6.0 V and reduced power is not active.
The DTC runs continuously when the above conditions are met.

P0121

The ECM detects that the throttle position sensor 1 voltage is stuck in range for greater than 1 s.

P0122

The ECM detects the throttle position sensor 1 signal voltage is less than 0.32 V for greater than 1 s.

P0123

The ECM detects the throttle position sensor 1 signal voltage is greater than 4.7 V for greater than 1 s.

P0222

The ECM detects the throttle position sensor 2 signal voltage is less than 0.25 V for greater than 1 s.

P0223

The ECM detects the throttle position sensor 2 signal voltage is greater than 4.6 V for greater than 1 s.

P16A0

The ECM detects a low voltage circuit condition on the throttle position sensor signal circuit for greater than 1 s.

P16A1

The ECM detects a high voltage circuit condition on the throttle position sensor signal circuit for greater than 1 s.

P16A2

The ECM detects an incorrect message was received over the throttle position sensor signal circuit for greater than 1 s.

P2135

The ECM detects that throttle position sensor 1 and 2 disagree greater than 7-10 percent for greater than 1 s.

DTCs P0121 is a Type B DTC.
DTCs P0122, P0123, P0222, P0223, P16A0, P16A1, P16A2, and P2135 are Type A DTCs.
The ECM commands the throttle actuator control (TAC) system to operate in a Reduced Engine Power mode.
A message center or an indicator displays Reduced Engine Power.
Under certain conditions, the ECM commands the engine OFF.

DTCs P0121 is a Type B DTC.
DTCs P0122, P0123, P0222, P0223, P16A0, P16A1, P16A2, and P2135 are Type A DTCs.

A high resistance condition on the throttle position and throttle actuator control circuits could cause a DTC to set.
If the accelerator pedal is pressed to the wide open throttle position, the throttle blade angle or Throttle Position angle is limited to less than 40 percent.

Schematic Reference

Connector End View Reference

Throttle Actuator Control (TAC) System Description

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Ignition ON
Verify that DTC P0601-P0606, P06A3, and P16F3 is not set. If any of the DTCs are set Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for further diagnosis. If none of the DTCs are set
Verify the scan tool Throttle Body Idle Airflow Compensation parameter is less than 90 %. 90 % or greater Refer to «Throttle Body Cleaning»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__throttle-body-cleaning) . If less than 90 %
Verify the scan tool Throttle Position Sensor 1 and Throttle Position Sensor 2 voltage parameters are greater than 0.0 V. If 0.0 V Refer to Circuit/System Testing below. If greater 0.0 V
Verify the Throttle Position Sensors 1 and 2 Agree/Disagree parameter displays Agree while performing the Throttle Sweep Test with a scan tool. If Disagree Test or replace the Q38 throttle body assembly. If Agree
Verify DTC P0121, P0122, P0123, P0222, P0223, P16A0, P16A1, P16A2, and P2135 is not set. If any of the DTCs are set Refer to Circuit/System Testing below. If none of the DTCs are set
Determine the current vehicle testing altitude.
Verify the scan tool MAP Sensor pressure parameter is within range specified in the «Altitude Versus Barometric Pressure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__altitude-versus-barometric-pressure) table. The MAP Sensor pressure is not in range Refer to «DTC P0106»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) . The MAP Sensor pressure is within range
Engine idling.
Verify the scan tool MAP Sensor pressure parameter is between 26-52 kPa (3.8-7.5 psi) and changes with accelerator pedal input. If not between 26-52 kPa (3.8-7.5 psi) or does not change Refer to «DTC P0106»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) . If between 26-52 kPa (3.8-7.5 psi) and changes
Verify the scan tool MAF Sensor g/s parameter changes smoothly and gradually as the engine speed is increased and decreased while performing the actions listed below. Engine idling Perform the scan tool snapshot function. Increase the engine speed slowly to 3, 000 RPM and then back to idle. Exit from the scan tool snapshot and review the data. Observe the MAF Sensor parameter frame by frame with a scan tool. The MAF Sensor parameter does not change smoothly and gradually Refer to «DTC P0101»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) . The MAF Sensor parameter changes smoothly and gradually
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/Failure Records data.
Verify the DTC does not set. If the DTC sets Refer to Circuit/System Testing below. If the DTC does not set
All OK

Ignition OFF, and all vehicle systems OFF, disconnect the harness connector at Q38 throttle body assembly. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 5 ohms between the low reference circuit terminal 4 and ground. If 5 ohms or greater Ignition OFF, disconnect the harness connector at the K20 engine control module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 engine control module. If less than 5 ohms
Ignition ON.
Test for 4.8-5.2 V between the 5 V reference circuit terminal 5 and ground. If less than 4.8 V Ignition OFF, disconnect the harness connector at the K20 engine control module. Test for infinite resistance between the 5 V reference circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the 5 V reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 engine control module. If greater than 5.2 V Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON. Test for less than 1 V between the 5 V reference circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K20 engine control module. If between 4.8-5.2 V
Ignition ON.
Test for 4.8-5.2 V between the signal circuit terminal 3 and ground. If less than 4.8 V Ignition OFF, disconnect the harness connector at the K20 engine control module. Test for infinite resistance between the signal circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 engine control module. If greater than 5.2 V Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K20 engine control module. If between 4.8-5.2 V
Test or replace the Q38 throttle body assembly.

«Throttle Body Assembly Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming, and setup

Install any components that have been removed or replaced during diagnosis.
Perform any adjustments, programming or setup procedures that are required when a component is removed or replaced.
Clear the DTCs with a scan tool.
Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down.
Ignition ON.
Verify the Throttle Position Sensors 1 and 2 Agree/Disagree parameter displays Agree while performing the Throttle Sweep Test with a scan tool. If Disagree Test or replace the Q38 throttle body assembly. If Agree
If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If any DTC sets Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for further diagnosis. If no DTC sets
All OK

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
ECT Sensor Signal	P0117, P0119	P0118	P0118	P0116, P0119, P0128
Low Reference		P0118, P0119	P0118	P0119, P0128

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The ignition is ON, or the engine is running Parameter Normal Range: Varies with ambient temperature, within a range of -39 to +120°C (-38 to +248°F)
ECT Sensor Signal	140°C (284°F)	40°C (-40°F)	40°C (-40°F)
Low Reference		40°C (-40°F)	40°C (-40°F)

ECT Sensor

The purpose of this diagnostic is to analyze the performance of the thermostat by comparing the measured ECT to a modeled ECT using information from the following inputs

ECT
Engine load
Intake air temperature (IAT)
Mass air flow (MAF)
Vehicle speed (VS)

The ECM uses the start-up ECT and the start-up intake air temperature (IAT) to begin the diagnostic calculation. The air flow into the engine is accumulated, and vehicle speed, distance, engine load, and engine run time are also factored in to determine if the ECT does increase normally and then maintains that temperature within a calibrated range of the modeled ECT.

DTC P0102, P0103, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, or P0501 is not set.
The decrease in ECT after engine start is within a calibrated range.
The decrease in IAT after engine start is within a calibrated range.
The engine idle time is less than 40 %.
The engine run time is greater than 8 s.
The engine run time at minimum load is less than 50 %.
The engine run time at maximum load is less than 90 %.
The ignition voltage is greater than 10 V.
The start-up ECT is between -10 and +75°C (14-167°F).
The start-up IAT is warmer than -10°C (14°F).
The DTC runs once per drive cycle within the enabling conditions.

The ECM determines that the modeled ECT has met the calibrated target of 92°C (198°F) and the measured ECT is less than 81°C (178°F) for greater than 2 s.

DTC P0128 is a Type B DTC.
The Engine Coolant Temperature Gauge is inoperative.
The cooling fans will be commanded ON.
The AC compressor will be commanded OFF.

DTC P0128 is a Type B DTC.

DTC P0128 occurring with insufficient vehicle interior heating is an indication of improper thermostat operation.
Corrosion on the ECT sensor terminals or the ECT harness connector results in a greater voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a colder ECT.
A slight to moderate resistance in the ECT sensor signal circuit or low reference circuit will affect this diagnostic. This condition results in a greater voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a colder ECT.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information.

Turn OFF the ignition.
Inspect the cooling system surge tank for the proper engine coolant level. Refer to «Cooling System Leak Testing»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-leak-testing) , and «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-ge) .
If the ignition has been OFF for 8 h or greater, the IAT, the ambient temperature, and the ECT should be within 9°C (16°F) of each other. Ignition ON, observe the scan tool IAT Sensor, Ambient Temperature, and the ECT Sensor parameters. Compare those sensor parameters to each other and also to the ambient temperature to determine if the ECT sensor is skewed colder.
Engine running, observe the ECT Sensor parameter. The reading should be between -39 to +120°C (-38 to +248°F) depending on the current ambient temperature and the vehicle operating conditions.
Use the scan tool to verify the proper operation of the engine cooling system fans.
Verify the proper heat range, and the operation of the thermostat. Refer to «Thermostat Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis) .
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.

Ignition OFF, disconnect the harness connector at the B34 engine coolant temperature sensor.
Vehicle OFF, all systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohms between the low reference circuit terminal A 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 K20 engine control module.
Ignition ON, verify the scan tool ECT Sensor parameter is colder than -39°C (-38°F). If warmer than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the K20 engine control module.
Install a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT Sensor parameter is warmer than 149°C (300°F). If colder than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
If the circuits test normal, test or replace the B34 engine coolant temperature sensor.

Measure and record the resistance of the ECT sensor at various ambient temperatures, then compare those measurements to the «Temperature Versus Resistance (Engine Coolant Temperature Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-engine-coolant-temperature) table.
Measure and record the resistance of the IAT sensor at various ambient temperatures, then compare those measurements to the «Temperature Versus Resistance (Engine Coolant Temperature Sensor)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__temperature-versus-resistance-engine-coolant-temperature) table.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Engine Coolant Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Engine Coolant Thermostat Replacement (LUK)»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__engine-coolant-thermostat-replacement-luk) , «Engine Coolant Thermostat Replacement (V6)»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
H2OS Jigh Signal	P0131, P0137	P0132, P0134, P0138, P0140	P0132, P0134, P0138, P0140	P0132, P0134, P0138, P0140, P2A00	P0133, P013A, P013B, P013E, P013F, P015A, P015B, P1133
H2OS Low Signal	P0131, P0137	P0132, P0134, P0138, P0140	P0132, P0134, P0138, P0140	P0132, P0134, P0138, P0140, P2A00	P0133, P013A, P013B, P013E, P013F, P015A, P015B, P1133

HO2S Sensor 1 Voltage

Circuit	Normal Range	Short to Ground	Open	Short to Voltage
H2OS High Signal	200-800 mV	0V	Approximately 1.9V	Approximately 1.9V
H2OS Low Signal	200-800 mV	0V	Approximately 1.9V	Approximately 1.9V

The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,275 mV. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases toward 0 mV indicates a lean fuel mixture.

The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the control module to calculate the air-to-fuel ratio sooner.

P0131 and P0137

DTCs P0106, P0107, P0108, P0201, P0202, P0203, P0204, P0411, P0412, P0418, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496 are not set.
The Loop Status parameter is Closed.
The Ignition voltage is between 10-32V.
The fuel level is greater than 10 percent.
The ethanol content is less than 87 percent.
Device controls are not active.
* Decel fuel cut-off is not active.
* DTC P0131 runs when the above conditions are met for 5s.

P0132

DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0201, P0202, P0203, P0204, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496 are not set.
The Loop Status parameter is Closed.
The Ignition voltage is between 10-32V.
The fuel level is greater than 10 percent.
The ethanol content is less than 87 percent.
Fuel control state is not in power enrichment.
DTC P0132 runs when the above conditions are met for 5s.

P0134 and P0140

* DTCs P0068, P0101, P0102, P0103, P0120, P0121, P0122, P0123, P0220, P0222, P0223, P1516, P2101, P2119, P2135, P2176 are not set.
The Ignition voltage is between 10-32V.
The engine run time is greater than 150s.
The fuel composition is less than 87 percent ethanol.
DTCs P0134 and P0140 run continuously when the above conditions are met.

P0138

DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0201, P0202, P0203, P0204, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496 are not set.
The Loop Status parameter is Closed.
The Ignition voltage is between 10-32V.
The fuel level is greater than 10 percent.
The engine run time is greater than 110s
The fuel composition is less than 87 percent ethanol.
Fuel control state is not in power enrichment.
DTC P0138 runs when the above conditions are met for 5s.

P2A00

DTCs P0068, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0131, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P1516, P2101, P2119, P2135, P2176 are not set.
The Engine Run Time parameter is more than 100s.
The Ignition voltage is between 10-32V.
The Mass Airflow (MAF) Sensor parameter is between 3.2-30g/s.
The ECT Sensor parameter is more than 70°C (158°F).
DTC P2A00 runs continuously when the above conditions are met for 5s.

DTC P0131

The ECM detects that the HO2S 1 voltage parameter is less than 50 mV.
DTC P0131 sets within 50s when the above condition is met.

DTC P0132

The ECM detects that the HO2S 1 voltage parameter is more than 1,050 mV.
DTC P0132 sets within 15s when the above condition is met.

DTC P0134

The ECM detects that the HO2S 1 voltage is greater than 1,700 mV.
DTC P0134 sets within 100s when the above conditions are met.

DTC P0137

The ECM detects that the HO2S 2 voltage parameter is less than 50 mV.
* DTC P0137 sets within 50s when the above condition is met.

DTC P0138

The ECM detects that the HO2S 2 voltage parameter is more than 1,050 mV.
DTC P0138 sets within 15s when the above condition is met.

DTC P0140

The ECM detects that the HO2S 2 voltage is greater than 1,700 mV.
DTC P0140 sets within 25s when the above conditions are met.

DTC P2A00

The ECM detects that the Loop Status parameter is open.
DTC P2A00 sets within 50s when the above condition is met.

DTCs P0131, P0132, P0134, P0137, P0138, P0140, and P2A00 are Type B DTCs.

Schematic Reference

Connector End View Reference

Throttle Actuator Control (TAC) System Description

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the DTC information with a scan tool. Verify no B52 HO2S heater DTCs are set. If a B52 HO2S heater DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Engine running, observe the appropriate scan tool B52 HO2S voltage parameter. The reading should be within the range of 50-1,050 mV.
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.

Ignition OFF, disconnect the appropriate B52 HO2S harness connector.
Ignition ON, observe the appropriate scan tool HO2S voltage parameter. The parameter should display approximately 1.9V. If less than the specified range, test the high and low signal circuits for a short to ground. If both signal circuit test normal, replace the K20 ECM.
Ignition ON, test for 2.5-3.0V between the high signal circuit terminal B and ground. If greater than the specified range, test the high signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM. If less than the specified range, test the high signal circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
Ignition OFF, connect a 3A fused jumper wire between the high signal circuit terminal B and the low signal circuit terminal A.
Ignition ON, verify the scan tool HO2S parameter displays 0.0V. If greater than the specified range, test the low signal circuit for an open/high resistance or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
6. If all circuits test normal, test or replace the appropriate B52 HO2S.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«HEATED OXYGEN SENSOR REPLACEMENT - SENSOR 1»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«HEATED OXYGEN SENSOR REPLACEMENT - SENSOR 2»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
Perform the scan tool Heated Oxygen Sensor Resistance Learn Reset after replacing a HO2S.
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
H2OS Jigh Signal	P0131, P0137	P0132, P0134, P0138, P0140	P0132, P0134, P0138, P0140	P0132, P0134, P0138, P0140, P2A00	P0133, P013A, P013B, P013E, P013F, P015A, P015B, P2A00
H2OS Low Signal	P0131, P0137	P0132, P0134, P0138, P0140	P0132, P0134, P0138, P0140	P0132, P0134, P0138, P0140, P2A00	P0133, P013A, P013B, P013E, P013F, P015A, P015B, P2A00

Circuit	Normal Range	Short to Ground	Open	Short to Voltage
H2OS Jigh Signal	200-800 mV	0V	Approximately 1.9V	Approximately 1.9V
H2OS Low Signal	00-800 mV	0V	Approximately 1.9V	Approximately 1.9V

The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. While the engine runs, the HO2S heats up and begins to generate a voltage within a range of 0-1,275mV. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine the air-to-fuel ratio. An HO2S voltage that increases toward 1,000mV indicates a rich fuel mixture. An HO2S voltage that decreases toward 0mV indicates a lean fuel mixture.

P0133

DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0128, P0131, P0132, P0134, P0201, P0202, P0203, P0204, P0300, P0411, P0412, P0418, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496 are not set.
The engine coolant temperature (ECT) is hotter than 70°C (158°F).
The Ignition voltage is between 10-32V.
The fuel level is greater than 10 percent.
The engine run time is greater than 120s.
The engine speed is between 1,000-3,500 RPM.
* Decel fuel cut-off is not active.
* The HO2S heaters have been ON for greater than 40s.
The intake air temperature (IAT) is hotter than -40°C (-40°F).
The fuel composition is less than 87 percent ethanol.
The barometric pressure is greater than 70 kPa.
The fuel control is not in power enrichment.
Decel fuel cut-off is not active.
The Mass Airflow (MAF) Sensor parameter is between 14-40g/s.
The fuel state is in Closed Loop.
DTCs P0133 runs once per drive cycle when the above conditions are met for 3s.

P013A

* DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P013B, P013E, P013F, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0300, P0411, P0412, P0418, P1174, P1516, P2101, P2119, P2135, P2176, P2270, P2271 are not set.
The system voltage is between 10-32V.
The fuel level is greater than 10 percent.
Engine run time is equal to or more than 40s.
DTCs P013E and P2270 have run and passed.
DFCO is active.
The accelerator pedal position (APP) is stable.
This DTC runs once per trip.

P013B and P013F

DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P013A, P013E, P013F, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0300, P0411, P0412, P0418, P1174, P1516, P2101, P2119, P2135, P2176, P2270, P2271 are not set.
The system voltage is between 10-32V.
The fuel level is greater than 10 percent.
DTCs P013A, P013E, P013F, P2270, and P2271 have run and passed.
DTCs P013B and P013F run once per trip.

P013E

DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P013A, P013E, P013F, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0300, P0411, P0412, P0418, P1174, P1516, P2101, P2119, P2135, P2176, P2270, P2271 are not set.
The system voltage is between 10-32V.
The fuel level is greater than 10 percent.
DTC P2270 has run and passed.
DFCO is active.
The APP is stable.
This DTC runs once per trip.

P015A and P015B

DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1516, P2101, P2119, P2135, P2176 are not set.
The system voltage is between 10-32V.
The intake air temperature (IAT) is warmer than -40°C (-40°F).
The engine coolant temperature (ECT) is greater than 70°C (158°F).
The HO2S heater is on for greater than 180s.
The fuel level is greater than 10 percent.
The engine run time is greater than 120s.
The engine speed is between 1,000-2,300 RPM.
The vehicle speed is between 51-120 kph (31.7-74.6 mph).
The mass airflow (MAF) is between 3-12g/s.
The device controls are not active.
The evaporative emission (EVAP) diagnostics are not in control of purge.
The predicted catalytic converter temperature is between 600-900°C (1,112-1,652°F).
The fuel system is in Closed Loop/
The DTCs run once per drive cycle when the above conditions are met.

P2270

DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P013A, P013B, P013E, P013F, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0300, P0411, P0412, P0418, P1174, P1516, P2101, P2119, P2135, P2176, P2270, P2271 are not set.
The system voltage is between 10-32V.
The fuel level is greater than 10 percent.
The pedal position is less than 4 percent.
The engine speed is 1,250-2,300 RPM.
The engine air flow is equal to or less than 12g/s.
The vehicle speed is between 55-120 kph (34.2-74.6 mph).
The fueling state is in Closed Loop.
The EVAP is not in control of purge.
he HO2S heaters have been on more than 180s.
The predicted catalytic converter temperature is between 600-900°C (1,112-1,652°F).
This DTC runs once per trip when all of the above conditions have been met for 1s.

P2271

DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P013A, P013B, P013E, P013F, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0300, P0411, P0412, P0418, P1174, P1516, P2101, P2119, P2135, P2176, P2270 are not set.
The system voltage is between 10-32V.
The fuel level is greater than 10 percent.
The engine speed is 1,250-2,300 RPM.
The engine air flow is between 3-12g/s.
The vehicle speed is between 55-120 kph (34.2-74.6 mph).
The fueling state is in Closed Loop.
The EVAP is not in control of purge.
Power take-off is not active.
The HO2S heaters have been on more than 180s.
The predicted catalyst temperature is between 600-900°C (1,112-1,652°F).
* DTCs P013A, P013E, and P2270 have run and passed.
DFCO is active.
The APP is stable.
This DTC runs once per trip when all of the above conditions have been met for 1s.

P0133

* The ECM detects that the HO2S 1 average response time is greater than a calculated value.
* DTC P0133 sets within 60s when the above condition is met.

P013A

The ECM detects that the accumulated mass air flow monitored during rich-to-lean transitions between 450-150mV is greater than a calibrated value.

P013B

The ECM detects that the accumulated mass air flow monitored during lean-to-rich transitions between 300-600mV is greater than a calibrated value.

P013E

The ECM detects that the O2 sensor cannot achieve voltage below 450 mV within a calibrated value of accumulated air flow.

P013F

The ECM detects that the O2 sensor cannot achieve voltage above 300 mV within a calibrated value of accumulated air flow.

P015A

The ECM detects that the length of time to change from rich to lean is greater than a calibrated value.
DTC P015A sets within 60s when the above condition is met.

P015B

* The ECM detects that the length of time to change from lean to rich is greater than a calibrated value.
DTC P015B sets within 60s when the above condition is met.

P2270

The ECM detects that the O2 sensor cannot achieve voltage equal to or more than 775 mV.
* The ECM detects that the accumulated mass air flow monitored during the Stuck Lean Voltage Test is more than a calibrated value.

P2271

The ECM detects that the O2 sensor cannot achieve voltage equal to or less than 100 mV.
The ECM detects that the accumulated mass air flow monitored during the Stuck Rich Voltage Test is more than a calibrated value.

DTCs P0133, P013E, P013F, P2270, and P2271 are Type B DTCs.
DTCs P013A, P013B, P015A, and P015B are Type A DTCs.

DTCs P0133, P013E, P013F, P2270, and P2271 are Type B DTCs.
DTCs P013A, P013B, P015A, and P015B are Type A DTCs.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the DTC information with a scan tool. Verify no B52 HO2S heater DTCs are set. If a B52 HO2S heater DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Verify none of the following conditions exist: Lean or rich fuel injectors. Refer to «FUEL INJECTOR SOLENOID COIL TEST»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) . Water intrusion in the HO2S harness connector. Low or high fuel system pressure. Refer to appropriate Fuel System Diagnosis information. * Fuel that is contaminated. Refer to «FUEL SYSTEM CLEANING»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__fuel-system-cleaning) . Fuel saturation of the evaporative emission (EVAP) canister. * Exhaust leaks. Refer to «EXHAUST LEAKAGE»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__exhaust-leakage) . Engine vacuum leaks. Engine oil consumption. Engine coolant consumption. Refer to «LOSS OF COOLANT»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant) .
Engine running, observe the appropriate scan tool B52 HO2S voltage parameter. The reading should be within the range of 50-1,050 mV.
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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«HEATED OXYGEN SENSOR REPLACEMENT - SENSOR 1»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«HEATED OXYGEN SENSOR REPLACEMENT - SENSOR 2»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
Perform the scan tool Heated Oxygen Sensor Resistance Learn Reset after replacing a HO2S.
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. The ECM monitors the heated oxygen sensor (HO2S) signal voltage and adjusts the fuel delivery based on the signal voltage while in Closed Loop. A change made to the fuel delivery changes the long and short term fuel trim (FT) values. The short term FT values change rapidly in response to the HO2S voltage signals. These changes fine tune the engine fueling. The long term FT makes coarse adjustments in order to maintain an optimum air/fuel ratio. The ideal FT values are around zero percent. A positive FT value indicates that the ECM is adding fuel in order to compensate for a lean condition. A negative FT value indicates that the ECM is reducing the amount of fuel in order to compensate for a rich condition.

DTCs P0053, P0101, P0102, P0103, P0106, P0107, P0108, P0131, P0132, P0133, P0134, P0135, P0178, P0179, P0201-P0204, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301-P0304, P0411, P0442, P0443, P0455, P0496, P0506, P0507, P1133, P1248, P1249, P124A, P124B, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157, P2227, P2228, P2229, P2230, P2269, P2440, P2444, or P2A00 are not set.
The engine is in Closed Loop status.
The catalyst monitor intrusive test is not active.
The post O2 sensor intrusive test is not active.
The device controls are not active.
The EVAP leak test is not active.
The engine coolant temperature (ECT) is between -20 and +150°C (-4 and +302°F).
The intake air temperature (IAT) is between -20 and +150°C (-4 and +302°F).
The manifold absolute pressure (MAP) is between 15-255 kPa (2.2-37 PSI).
The engine speed is between 400-6, 600 RPM.
The mass air flow (MAF) is between 1-512 g/s.
The barometric pressure (BARO) is greater than 70 kPa (10.2 PSI).
The fuel level is greater than 10 percent.
These DTCs run continuously when the above conditions have been met.

The long term FT weighted average value is greater or less than a calibrated value.
The above condition is present for approximately 3 minutes after the conditions for running the DTC have been met.

DTCs P0171 and P0172 are Type B DTCs.

The normal Short Term FT parameter should be between +10 percent and -10 percent, with near 0 percent the optimum, with the engine running at operating temperature.
The Long Term FT parameter should be between +10 percent and -10 percent, with near 0 percent the optimum, with the engine running at operating temperature.
Certain aftermarket air filters may cause a DTC to set.
Certain aftermarket air induction systems or modifications to the air induction system may cause a DTC to set.
Certain aftermarket exhaust system components may cause a DTC to set.

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Verify that no other DTCs are set. If any other DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Ignition ON, engine OFF, observe the manifold absolute pressure (MAP) sensor parameter. The MAP sensor pressure should be within the range specified for your altitude. Refer to «Altitude Versus Barometric Pressure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__altitude-versus-barometric-pressure) . If the MAP sensor does not indicate the correct barometric pressure, refer to «DTC P0106»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) .
With the engine idling, observe the mass air flow (MAF) sensor parameter. The MAF sensor parameter should be between 2-6 g/s at idle. If the MAF sensor parameter is not between 2-6 g/s at idle, refer to «DTC P0101»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) , or «DTC P0102 or P0103»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) .

P0171

Note. EVAP purge enablement may cause the FT to be momentarily outside the normal range.

Allow the engine to reach operating temperature. With the engine running, observe the Long Term FT parameter with a scan tool. The reading should be between 0-29 percent.

If greater than the specified range, inspect for the following

Vacuum hoses for splits, kinks, and improper connections
Insufficient fuel in the tank
Low fuel pressure-Refer to «Fuel System Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
Fuel contamination-Refer to «Alcohol/Contaminants-in-Fuel Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
Malfunctioning fuel injectors-Refer to «Fuel Injector Solenoid Coil Test»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
Missing, loose, or leaking exhaust components from the HO2S forward-Refer to «Symptoms - Engine Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__symptoms-engine-exhaust) .
Vacuum leaks at the intake manifold, the throttle body, and the injector O-rings
The air induction system and the air intake ducts for leaks or for a missing air filter element
A cracked EVAP canister
Evaporative pipes obstructed or leaking
The crankcase ventilation system for leaks-Refer to «Crankcase Ventilation System Inspection/Diagnosis (Without Turbocharger)»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__crankcase-ventilation-system-inspectiondiagnosis-without-tur) .
The HO2S for improper installation and for electrical wires or connectors that may have contacted the exhaust system
The HO2S signal circuit open, shorted to ground, or shorted to the low reference circuit
Malfunctioning engine components-Refer to «Symptoms - Engine Mechanical»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l) .

P0172

Note. EVAP purge enablement may cause the FT to be momentarily outside the normal range.

Allow the engine to reach operating temperature. With the engine running, observe the Long Term FT parameter with a scan tool. The reading should be between -16 and 0 percent.

If less than the specified range, inspect for the following

Vacuum hoses for splits, kinks, and improper connections
The air intake duct for being collapsed or restricted
The air filter for being dirty or restricted
Objects blocking the throttle body
Excessive fuel in the crankcase due to leaking fuel injectors
The EVAP control system for improper operation
Excessive fuel pressure-Refer to «Fuel System Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
Malfunctioning fuel injectors-Refer to «Fuel Injector Solenoid Coil Test»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
Fuel contamination-Refer to «Alcohol/Contaminants-in-Fuel Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
The HO2S for improper installation and for electrical wires or connectors that may have contacted the exhaust system
The HO2S signal circuit shorted to voltage
Malfunctioning engine components-Refer to «Symptoms - Engine Mechanical»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l) .

Perform the Diagnostic Repair Verification after performing the diagnostic procedure.

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5 V Reference	P018C, P0641	P018C	P018D, P0641	P06A6
Signal	P018C	P018C	P018D	P018B
Low Reference		P018D		P06A6

The fuel pressure sensor is located on the fuel line. The fuel pressure sensor monitors the fuel pressure in the fuel line. The fuel pump control module monitors the voltage signal from the fuel pressure sensor.

The engine is running.
DTC P018C, P018D, P0231, P0232, P023F, P064A, P1255 or P06A6 are not active.
DTC P0641 has not failed this ignition cycle.
Fuel pump control is enabled and the fuel pump control state is normal.
The engine has been running for at least 5 seconds.

The fuel pump control module does not detect a change in the fuel pressure of at least 30 kPa (4.4 psi) when the fuel pump is operating. The fuel pressure sensor performance diagnostic provides a means to detect fuel pressure sensor output that is stuck within the normal operating range of the sensor.

DTC P018B, P018C and P018D are Type A DTCs.

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

Schematic Reference

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Note. Verify that the fuel tank is not empty. Only perform this diagnostic if there is at least 2 gallons of fuel in the fuel tank. Clear the DTC, and start and run the engine. Verify that the DTC P018B resets before proceeding with the circuit system testing. If the DTC does not reset, refer to Diagnostic Aids above.

Ignition OFF, disconnect the harness connector at the B47 fuel pressure sensor.
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 10 ohms between the low reference circuit terminal 2 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 K27 fuel pump flow control module.
Ignition ON, test for 4.8-5.2 V between the B47 fuel pressure sensor 5 V reference circuit terminal 3 and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K27 fuel pump flow control module. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K27 fuel pump flow control module.
Verify the scan tool fuel pressure sensor voltage is less than 1 V. If greater than the specified range, test the signal circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the K27 fuel pump flow control module.
Install a 3 A fused jumper wire between the signal circuit terminal 1 and the 5 V reference circuit terminal 3. Wait 15 seconds. Verify the scan tool fuel pressure sensor voltage is greater than 4.8 V. 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 K27 fuel pump flow control module.
If all circuits test normal, replace the B47 fuel pressure sensor.

Perform the Diagnostic Repair Verification after completing the repair.

«Fuel Pressure Sensor Replacement - Fuel Feed Pipe»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-36l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for fuel pump control module replacement, programming and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5 V Reference Voltage	P0192, P0193, P0641	P0192	P0641	P0191
Fuel Rail Pressure Sensor Signal	P0192	P0192	P0193	P0191
Low Reference		P0193, P0506		P0191

The fuel rail fuel pressure sensor detects fuel pressure within the fuel rail. The engine control module (ECM) provides a 5 V reference voltage on the 5 V reference circuit and ground on the low reference circuit. The ECM receives a varying signal voltage on the signal circuit. The ECM monitors the voltage on the fuel rail fuel pressure sensor circuits. When the fuel pressure is high, the signal voltage is high. When the fuel pressure is low, the signal voltage is low.

Condition 1

DTC P0016, P0017, P0068, P0090, P0091, P0092, P00C8, P00C9, P00CA, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0128, P0192, P0193, P0201, P0202, P0203, P0204, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301, P0302, P0303, P0304, P0335, P0336, P0340, P0341, P0351-P0354, P0365, P0366, P0506, P0507, P0627, P0628, P0629, P0722, P0723, P1248, P1249, P124A, P124B, P1682, P16F3, P2101, P2122, P2123, P2127, P2128, P2135, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157 is not set.
The engine is not cranking.
The ignition voltage is greater than 11 V.
The vehicle speed is less than or equal to 1 km/h (0.62 mph).
The low side fuel pressure is greater than or equal to 275 kPa (40 psi).
The Accelerator Pedal Position is 0 percent for 12.5 s.
DTC P0191 runs continuously when the above conditions have been met.

Condition 2 and 3

DTC P0016, P0017, P0068, P0090, P0091, P0092, P00C8, P00C9, P00CA, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0128, P0192, P0193, P0201, P0202, P0203, P0204, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301, P0302, P0303, P0304, P0335, P0336, P0340, P0341, P0351-P0354, P0365, P0366, P0506, P0507, P0627, P0628, P0629, P0722, P0723, P1248, P1249, P124A, P124B, P1682, P16F3, P2101, P2122, P2123, P2127, P2128, P2135, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157 is not set.
The engine is not cranking.
The ignition voltage is greater than 11 V.
The engine speed is between 1, 000-2, 200 RPM.
The vehicle speed is greater than or equal to 45 km/h (27.96 mph).
The low side fuel pressure is greater than or equal to 275 kPa (40 psi).
The Desired Fuel Rail Pressure is between 7-8 MPa (1, 015-1, 160 psi).
DTC P0191 runs continuously when the above conditions have been met.

Condition 4

DTC P0016, P0017, P0068, P0090, P0091, P0092, P00C8, P00C9, P00CA, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0128, P0192, P0193, P0201, P0202, P0203, P0204, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301, P0302, P0303, P0304, P0335, P0336, P0340, P0341, P0351-P0354, P0365, P0366, P0506, P0507, P0627, P0628, P0629, P0722, P0723, P1248, P1249, P124A, P124B, P1682, P16F3, P2101, P2122, P2123, P2127, P2128, P2135, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157 is not set.
The engine is not cranking.
The vehicle speed is greater than or equal to 30 km/h (18.64 mph).
The engine speed is greater than or equal to 2, 000 RPM.
DTC P0191 runs continuously when the above conditions have been met.

Condition 1

The difference between the low side fuel pressure and the high side fuel pressure is less than or equal to -0.65 MPa (-94 psi) or greater than or equal to 0.6 MPa (87 psi) with the high pressure fuel pump actuator commanded OFF. The condition exists for greater than 3 s.

Condition 2

The difference between the relief pressure and the measured high pressure is less than or equal to -5 MPa (-725 psi) with the high pressure fuel pump actuator commanded ON. The condition exists for greater than 2 s.

Condition 3

The difference between the commanded high pressure and the measured high pressure is greater than or equal to 3 MPa (435 psi) and the modeled injection pressure is greater than or equal to 3 MPa (435 psi) with the high pressure fuel pump actuator commanded ON. The condition exists for greater than 3 s.

Condition 4

The difference between the measured maximum high pressure and the measured minimum high pressure is less than or equal to 0.1 MPa (14.5 psi) with the high pressure fuel pump actuator commanded ON. The condition exists for greater than 60 s.

DTC P0191 is a Type A DTC.
A message center or an indicator may display Reduced Engine Power.

DTC P0191 is a Type A DTC.

A condition with the fuel tank fuel pump module or the fuel pump control module may set this DTC.

Schematic Reference

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Observe the scan tool DTC information, verify DTC P0627, P0628, P0629, P0641, P069E or U0109 is not set. If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Engine idling, observe the scan tool Fuel Rail Pressure Sensor parameter. The pressure should be approximately 2.96-3.24 MPa (429-470 psi).
Engine idling, the scan tool Fuel Rail Pressure Sensor should be close to the scan tool Desired Fuel Rail Pressure. As the engine speed increases, the Desired Fuel Rail Pressure and the Fuel Rail Pressure Sensor should closely match each other.
Move related harnesses/connectors of the B47B fuel rail fuel pressure sensor and verify the engine does not stumble, stall, or change engine speed. If the engine stumbles, stalls, or changes engine speed, test or repair the suspected harness or connection.
Observe the DTC information with a scan tool, DTC P0191 should not set.
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.

Ignition OFF, disconnect the fuel injector multi-way harness connector X160.
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 ohms between the low reference circuit terminal 5 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 K20 ECM.
Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 11 and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Ignition ON, verify the scan tool Fuel Rail Pressure Sensor voltage parameter is less than 0.02 V. If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Connect a 3 A fused jumper wire between the signal circuit terminal 12 and the 5 V reference circuit terminal 11. Verify the scan tool Fuel Rail Pressure Sensor Voltage parameter is greater than 4.96 V. If less than the specified value, test the signal circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the K20 ECM.
Ignition OFF, remove the intake manifold.
Connect the fuel injector multi-way harness connector X160.
Disconnect the B47B fuel rail fuel pressure sensor connector.
Ignition OFF, test for less than 5 ohms between the low reference circuit terminal C and ground. If greater than the specified range, test the low reference circuit for an open/high resistance.
Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal A and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If greater than the specified range, test the 5 V reference circuit for a short to voltage.
Ignition ON, verify the scan tool Fuel Rail Pressure Sensor voltage parameter is less than 0.02 V. If greater than the specified value, test the signal circuit for a short to voltage.
Connect a 3 A fused jumper wire between the signal circuit terminal B and the 5 V reference circuit terminal A. Verify the scan tool Fuel Rail Pressure Sensor voltage parameter is greater than 4.96 V. If less than the specified value, test the signal circuit for an open/high resistance or a short to ground.
If all circuits test normal, replace the B47B fuel rail fuel pressure sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5 V Reference Voltage	P0192, P0193, P0641	P0192	P0641	P0191
Fuel Rail Pressure Sensor Signal	P0192	P0192	P0193	P0191
Low Reference		P0193, P0506		P0191

The fuel rail fuel pressure sensor detects fuel pressure within the fuel rail. The engine control module (ECM) provides a 5 V reference voltage on the 5 V reference circuit and ground on the reference ground circuit. The ECM receives a varying signal voltage on the signal circuit. The ECM monitors the voltage on the fuel rail fuel pressure sensor circuits. When the fuel pressure is high, the signal voltage is high. When the fuel pressure is low, the signal voltage is low.

The engine is running.
The ignition voltage is greater than 11 V.
The DTCs run continuously within the enabling conditions.

P0192

The ECM detects that the fuel rail fuel pressure sensor signal voltage is low for greater than 6 s.

P0193

The ECM detects that the fuel rail fuel pressure sensor signal voltage is high for greater than 6 s.

DTCs P0192 and P0193 are Type A DTCs.
A message center or an indicator may display Reduced Engine Power.

DTCs P0192 and P0193 are Type A DTCs.

Schematic Reference

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the DTC information with a scan tool, DTC P0641 should not be set. If a DTC is set, refer to «DTC P0641, P0651, P0697, or P06A3 (ECM)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
Engine idling, observe the DTC information with a scan tool. DTC P0192 or P0193 should not set.
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.

Ignition OFF, disconnect the fuel injector multi-way harness connector X160.
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 ohms between the low reference circuit terminal 5 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 K20 ECM.
Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 11 and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Ignition ON, verify the scan tool Fuel Rail Pressure Sensor voltage parameter is less than 0.02 V. If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Connect a 3 A fused jumper wire between the signal circuit terminal 12 and the 5 V reference circuit terminal 11. Verify the scan tool Fuel Rail Pressure Sensor voltage parameter is greater than 4.96 V. If less than the specified value, test the signal circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the K20 ECM.
Ignition OFF, remove the intake manifold.
Connect the fuel injector multi-way harness connector X160.
Disconnect the B47B fuel rail fuel pressure sensor connector.
Ignition OFF, test for less than 5 ohms between the low reference circuit terminal C and ground. If greater than the specified range, test the low reference circuit for an open/high resistance.
Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal A and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If greater than the specified range, test the 5 V reference circuit for a short to voltage.
Ignition ON, verify the scan tool Fuel Rail Pressure Sensor voltage parameter is less than 0.02 V. If greater than the specified value, test the signal circuit for a short to voltage.
Connect a 3 A fused jumper wire between the signal circuit terminal B and the 5 V reference circuit terminal A. Verify the scan tool Fuel Rail Pressure Sensor voltage parameter is greater than 4.96 V. If less than the specified value, test the signal circuit for an open/high resistance or a short to ground.
If all circuits test normal, replace the B47B fuel rail fuel pressure sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Short from Supply Circuit to Control Circuit
Direct Fuel Injector High Voltage Supply Cylinder 1	P2147	P0201	P2148	P1248
Direct Fuel Injector High Voltage Control Cylinder 1	P0261	P0201	P0262, P2148	P1248
Direct Fuel Injector High Voltage Supply Cylinder 2	P2150	P0202	P2151	P1249
Direct Fuel Injector High Voltage Control Cylinder 2	P0264	P0202	P0265, P2151	P1249
Direct Fuel Injector High Voltage Supply Cylinder 3	P2153	P0203	P2154	P124A
Direct Fuel Injector High Voltage Control Cylinder 3	P0267	P0203	P0268, P2154	P124A
Direct Fuel Injector High Voltage Supply Cylinder 4	P2156	P0204	P2157	P124B
Direct Fuel Injector High Voltage Control Cylinder 4	P0270	P0204	P0271, P2157	P124B

The engine control module (ECM) supplies voltage to each fuel injector on the injector high voltage supply circuits. The ECM energizes each fuel injector by grounding the high voltage control circuit of the fuel injector. The ECM monitors the status of the injector high voltage supply circuits and the fuel injector high voltage control circuits. When a fuel injector circuit condition is detected by the ECM, the affected fuel injector(s) is disabled.

DTC P062B is not set.
The engine is running for greater than 5 s.
The ignition voltage is greater than 11 V.
The DTCs run continuously once the above conditions are met.

P0201, P0202, P0203, or P0204

The ECM detects the injector high voltage supply circuit or the injector high voltage control circuit is open for greater than 2 s.

P0261, P0264, P0267, or P0270

The ECM detects the injector high voltage control circuit is shorted to ground for greater than 2 s.

P0262, P0265, P0268, or P0271

The ECM detects the injector high voltage control circuit is shorted to voltage for greater than 2 s.

P1248, P1249, P124A, or P124B

The ECM detects the injector high voltage supply circuit is shorted to the injector high voltage control circuit for greater than 2 s.

P2147, P2150, P2153, or P2156

The ECM detects the injector high voltage supply circuit is shorted to ground for greater than 2 s.

P2148, P2151, P2154, or P2157

The ECM detects the injector high voltage supply circuit is shorted to voltage for greater than 2 s.

DTCs P0201, P0202, P0203, P0204, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P1248, P1249, P124A, P124B, P2147, P2148, P2150, P2151, P2153, P2154, P2156, and P2157 are Type A DTCs.

Performing the fuel injector coil test may help isolate an intermittent condition. Refer to «Fuel Injector Solenoid Coil Test»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool Injector Control Circuit Status parameters. An Injector Control Circuit Status parameter will change from OK or Not Run to Fault if there is a condition with the circuit or a connection.

Schematic Reference

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Observe the DTC information with a scan tool. DTC P0685 or P1682 should not set. If a DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Engine operating, observe the DTC information with a scan tool. DTC P0201, P0202, P0203, P0204, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P1248, P1249, P124A, P124B, P2147, P2148, P2150, P2151, P2153, P2154, P2156, or P2157 should not set.
Observe the scan tool Current Misfire Counter parameters. The Current Misfire Counters should not increment.
Ignition ON, observe the scan tool Cylinder 1-4 Injector Control Circuit Status parameters. Verify the Injector Control Circuit Status parameters display OK.
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.

Ignition OFF, disconnect the fuel injector multi-way harness connector X160.
Ignition ON, observe the appropriate scan tool Cylinder 1-4 Injector Control Circuit Status. The parameter should display Open. If not the specified value, test the appropriate high voltage supply circuit, ECM side, for a short to ground or the appropriate high voltage control circuit, ECM side, for a short to voltage. If the circuits test normal, replace the K20 ECM.
Ignition ON, connect a test lamp between the appropriate high voltage supply circuit and the high voltage control circuit. The Injector Control Circuit Status should transition from Open to OK. If not the specified value, test for the following conditions in the ECM side of the harness: An open/high resistance in the high voltage supply circuit An open/high resistance in the high voltage control circuit A short to ground in the high voltage control circuit A short to voltage in the high voltage supply circuit If the circuits test normal, replace the K20 ECM.
Ignition OFF, measure the resistance between the appropriate high voltage supply circuit and ground. The DMM should display OL ohms. If less than the specified range, test the high voltage supply circuit and the high voltage control circuit for a short to ground. If the circuits/connections test normal, test or replace the appropriate Q17 fuel injector(s).
Test for 2-3 ohms between the appropriate high voltage supply circuit and high voltage control circuit. If less than the specified range, test for a short between the high voltage supply circuit and high voltage control circuit. If the circuits/connections test normal, test or replace the appropriate Q17 fuel injector(s). If greater than the specified range, test the high voltage supply circuit and high voltage control circuit for an open/high resistance. If the circuits/connections test normal, test or replace the appropriate Q17 fuel injector.

«Fuel Injector Solenoid Coil Test»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures)
«Fuel Injector Balance Test»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Direct Fuel Injector Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open or High Resistance	Short to Voltage	Signal Performance
Control	P0231	P023F	P0232	P023F, P2635
Low Reference		P023F		P023F, P2635

The engine control module (ECM) supplies voltage to the fuel pump control module when the ECM detects that the ignition is on. The voltage from the ECM to the fuel pump control module remains active for 2 seconds, unless the engine is in crank or run. While this voltage is being received, the fuel pump control module supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel pressure.

P0231, P023F

The ignition voltage is between 9-18 V.

P0232

The control enable voltage signal supplied for the ECM to fuel pump control module is inactive for 4 seconds after engine has been shut off.

The fuel pump control module detects a fault on the fuel pump voltage circuit that is less than 4 V or greater than 4.5 V.

DTCs P0231, P0232, and P023F are Type A DTCs.

On vehicles equipped with a high pressure mechanical pump on Direct Fuel Injection engines, the vehicle may continue to run even though the pump in the fuel tank is not operating.

Schematic Reference

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the fuel pump ON and OFF using the scan tool ECM fuel pump output control. The fuel pump should turn ON and OFF.

Ignition OFF, disconnect the harness connector at the G12 fuel pump.
Connect a test lamp between the control circuit terminal 1 and ground.
Ignition ON, command the G12 fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF, as commanded. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K27 fuel pump control module. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K27 fuel pump control module.
Ignition OFF, connect a test lamp between the control circuit terminal 1 and the low reference circuit terminal 2.
Ignition ON, command the G12 fuel pump ON with a scan tool. The test lamp should illuminate. If the test lamp does not illuminate, test the low reference circuit terminal 2 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K27 fuel pump control module.
If all circuits test normal, replace the fuel tank G12 fuel pump module.

Perform the Diagnostic Repair Verification after completing the repair.

«Fuel Tank Fuel Pump Module Replacement (NT7)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__fuel-tank-fuel-pump-module-replacement) , «Fuel Tank Fuel Pump Module Replacement (NU6)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__fuel-tank-fuel-pump-module-replacement)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for fuel pump control module replacement, programming and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
FPCM Control	P025A	P025A		P025A

The ignition is ON.

The serial data message from the ECM to the fuel pump control module does not agree with the state of the control enable voltage signal supplied from the ECM to the fuel pump control module for more than 2 seconds.

DTC P025A is a Type A DTC.

Schematic Reference

Connector End View Reference

Description and Operation

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Note. Verify that the fuel tank is not empty. Only perform this diagnostic if there is at least 2 gallons of fuel in the fuel tank. Clear the DTC, and start and run the engine. Verify that the DTC resets before proceeding with the circuit system testing. If the DTC does not reset, refer to diagnostic aids above.

Ignition OFF, disconnect the harness connector at the K27 fuel pump control module.
Ignition OFF, connect a test lamp between the control circuit terminal 13 and ground.
Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
If all circuits test normal, replace the K27 fuel pump control module.

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for ECM or fuel pump control module replacement, programming and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) uses information from the crankshaft position sensor and the camshaft position sensors in order to determine when an engine misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM is able to detect individual misfire events. A misfire rate that is high enough can cause 3-way catalytic converter damage. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for catalytic converter damage are present. DTCs P0301 through P0304 correspond to cylinders 1 through 4. If the ECM is able to determine that a specific cylinder is misfiring, the DTC for that cylinder will set, and the corresponding fuel injector is disabled. The ECM will re-enable the fuel injector after 3 crankshaft revolutions when the misfire is not current. The ECM will re-enable the fuel injector after 6 crankshaft revolutions when the misfire is not current, if the vehicle is equipped with a manual transmission.

DTC P0010, P0011, P0013, P0014, P0016, P0017, P0068, P00C8, P00C9, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0117, P0118, P0119, P0121, P0122, P0123, P0191, P0192, P0193, P0222, P0223, P0335, P0336, P0340, P0341, P0365, P0366, P0606, P0651, P16F3, P2100, P2101, or P2135 is not set.
The engine speed is less than 1, 000 RPM and DTC P0315 is set.
The engine coolant temperature (ECT) is between -7 and +127°C (19 and 261°F).
If the ECT is colder than -7°C (+19°F) at start-up, this diagnostic will not run until the ECT is between 21 and 127°C (69 and 261°F).
The ignition voltage is between 9 and 32 V.
The evaporative emissions (EVAP) leak detection is not active.
The ECM is not detecting rough road signal.
The fuel level is at least 11 %.
The ECM is not in fuel cut-off or decel fuel cut-off mode.
DTCs P0300 through P0304 run continuously when the above conditions exist.

P0300

The ECM detects a crankshaft rotation speed variation indicating a misfire rate sufficient to cause emissions levels to exceed a predetermined value or a misfire rate high enough to cause catalyst damage.

P0301, P0302, P0303, P0304

The ECM detects a crankshaft rotation speed variation indicating a single cylinder misfire rate sufficient to cause emissions levels to exceed mandated standards.

DTCs P0300-P0304 are Type B DTCs.
The ECM disables the fuel injector of the misfiring cylinder when a misfire is present.

DTCs P0300-P0304 are Type B DTCs.

A misfire DTC could be caused by an excessive vibration from sources other than the engine. Inspect for the following possible sources: A tire or wheel that is out of round or out of balance Variable thickness brake rotors An unbalanced drive shaft Certain rough road conditions Transmission operation Broken or weak valve spring Cracked Spark Plug Insulators A damaged accessory drive component or belt ; remove the belt and safely operate the engine to evaluate if misfire counts go away.
High resistance in the circuits of the injectors may set a misfire DTC without setting an injector DTC. Test the injector circuits of the affected cylinder(s) for a high resistance if you suspect a condition.
If the condition is intermittent, observing the scan tool IC Circuit Test and Fuel Injector Circuit Test Status parameters may help isolate the condition. The circuit test status parameters will change from OK or Not Run to Fault/Malfunction if a condition exists.
A condition in the heated O2 sensor (HO2S) heater control circuits may set a DTC P0300.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
«Powertrain Component Views»(/buick/lacrosse/ii-2009-2013/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-powertrain-component-views)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 26792 HEI Spark Tester

For equivalent regional tools, refer to the appropriate regional parts catalog.

Engine idling at the normal operating temperature. Verify there is no abnormal engine noise. If there is an abnormal engine noise, refer to «Symptoms - Engine Mechanical»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l) .
Verify that no other DTCs are set. If a DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
Observe the scan tool Misfire Current Cyl. 1-4 parameters. The Misfire Current Counters should not be incrementing.
Engine idling, perform the Cylinder Power Balance test with a scan tool to isolate the misfiring cylinder. The engine speed should change when each injector is disabled.
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.

Verify that the following conditions do not exist: Vacuum hose splits, kinks, and incorrect connections Engine vacuum leaks Crankcase ventilation system for vacuum leaks Fuel pressure that is too low or too high-Refer to «Fuel System Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) . Contaminated fuel-Refer to «Alcohol/Contaminants-in-Fuel Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) . Exhaust system restrictions If you find any of the above conditions, repair as necessary.
Ignition OFF, remove the T8 ignition coil of the misfiring cylinder, but leave the electrical connector connected.
Inspect the ignition coil boot for the following conditions: Holes Tears Carbon tracking Oil contamination Water intrusion If you find any of the above conditions, repair as necessary.
Install the J 26792 HEI Spark Tester to the boot of the appropriate T8 ignition coil and ground.
Attempt to start the engine and observe the J 26792 HEI Spark Tester. The spark tester should spark. If there is no spark, refer to «Electronic Ignition System Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) for diagnosis of the ignition coil.
Ignition OFF, remove the spark plug from the misfiring cylinder. Verify that the spark plug does not exhibit the following conditions: Gas, coolant, or oil fouled-Refer to «Spark Plug Inspection»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__spark-plug-inspection) . Cracked, worn, incorrectly gapped-Refer to «Ignition System Specifications»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__ignition-system-specifications) . If there is a condition with the spark plug, replace the spark plug.
Exchange the suspected spark plug with another cylinder that is operating correctly.
Operate the engine under the conditions in which the misfire occurred. Observe the Misfire Current Cyl. 1-4 parameters with a scan tool. The misfire should not follow the spark plug exchange. If the misfire follows the spark plug, replace the spark plug.
If all conditions test normal, test or inspect for the following: A lean or rich Q17 fuel injector-Refer to «Fuel Injector Balance Test»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) . An engine mechanical condition-Refer to «Symptoms - Engine Mechanical»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l) .

«Ignition Coil Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Spark Plug Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)

Install any components or connectors that have been removed or replaced during diagnosis.
Perform any adjustment, programming or setup procedures that are required when a component or module is removed or replaced.
Clear the DTCs.
Turn OFF the ignition for 60 s.
If the repair was related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to the «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) and perform the appropriate diagnostic procedure.
Engine idling, observe the Misfire Current Cyl. 1-4 parameters with a scan tool. The misfire counter parameters should not be incrementing. If the misfire counter parameters are incrementing, a misfire still exists.
To verify that the performance of the catalytic converter has not been affected by the condition that set this DTC, perform the Repair Verification for DTC P0420. Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The crankshaft position system variation learn feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, and the crankshaft position sensor. The calculated error allows the engine control module (ECM) to accurately compensate for reference period variations. This enhances the ability of the ECM to detect misfire events over a wider range of engine speed and load conditions.

The crankshaft position system variation compensating values are stored in ECM memory after a learn procedure has been performed and the ignition switch is turned to the OFF position for at least 30 s. If the actual variation is not within the crankshaft position system variation compensating values stored in the ECM, DTC P0300 may set.

If the crankshaft position system variation values are not stored in the ECM memory or a proper ECM power down does not occur after completing the Crankshaft Position Learn Procedure, DTC P0315 sets.

DTC P0315 runs continuously.

The ECM detects that the crankshaft position system variation values are not stored in memory.

DTC P0315 is a Type A DTC.

This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test .

Schematic Reference

Connector End Views

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Note. The Crankshaft Position Variation Learn may have to be repeated up to 5 times before the procedure is successful.

Perform the «Crankshaft Position System Variation Learn»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__crankshaft-position-system-variation-learn) procedure. The scan tool should display Learned Successful. If the Crankshaft Position System Variation Learn Procedure cannot be performed successfully, inspect for the following conditions: Worn crankshaft main bearings A damaged or misaligned reluctor wheel Excessive crankshaft runout A damaged crankshaft-Refer to «Crankshaft and Bearing Cleaning and Inspection»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__crankshaft-and-bearing-cleaning-and-inspection) . Interference in the signal circuit of the crankshaft position sensor The ignition switch is in the ON position until there is insufficient system voltage. An ECM power disconnect with the ignition ON that may have erased the crankshaft position system variation values and set DTC P0315 Debris between the crankshaft position sensor and the reluctor wheel
Verify the Learn Procedure is successful. If the ECM is unable to complete the learn procedure, replace the K20 engine control module.

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for engine control module replacement, programming, and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Knock Sensor Signal	P0327, P06B6	P0325	P0328, P06B6	P0326
Low Reference	P0327		P0328

The knock sensor system enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The knock sensor produces an AC voltage signal that varies depending on the vibration level during engine operation. The ECM adjusts the spark timing based on the amplitude and the frequency of the knock sensor signal. The ECM receives the knock sensor signal through 2 isolated signal circuits. The ECM learns a minimum knock sensor noise level for all of the RPM range. The ECM monitors for a normal knock sensor signal. The ECM generates a 20 KHz signal on the output circuit and monitors that it is sent back and detected on the return circuit. The ECM processes the return signal to verify the internal knock sensor processor.

P0324 and P0326-Condition 1

Engine speed is between 400-8, 500 RPM.
Engine is running for greater than 2 s.
The engine coolant temperature (ECT) is warmer than -40°C (-40°F).
The intake air temperature (IAT) is warmer than -40°C (-40°F).
The DTCs run continuously when the above conditions are met.

P0326-Condition 2

Engine speed is between 2, 200-8, 500 RPM.
Engine is running for greater than 2 s.
The ECT is greater than -40°C (-40°F).
The IAT is greater than -40°C (-40°F).
The DTCs run continuously when the above conditions are met.

P06B6

Engine speed is between 400-3, 500 RPM.
Engine is running for greater than 2 s.
The engine coolant temperature (ECT) is warmer than -40°C (-40°F).
The intake air temperature (IAT) is warmer than -40°C (-40°F).
The DTC runs continuously when the above conditions are met.

P0324

The ECM detects that the knock sensor signal's performance is out of the normal expected range due to an excessive engine knock, or abnormal noise, or a flat signal; for greater than 10 s for at least 1 single cylinder.

P0326

The ECM detects that the knock sensor signal indicates the harness is connected, but the sensor is not properly bolted to the engine.
The above condition exist for greater than 10 s. OR
The ECM detects that the knock sensor signal indicates an excessive engine knock is present.
The above condition exist for greater than 10 s.

P06B6

The ECM has detected an internal knock sensor processor fault.

DTCs P0324, P0326, P0328, and P06B6 are Type B DTCs.
The ignition timing is retarded to reduce the potential of engine damaging spark knock.

DTCs P0324, P0326, P0328, and P06B6 are Type B DTCs.

Schematic Reference

Connector End View Reference

Electronic Ignition System Description

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Engine running, observe the DTC information with a scan tool. Verify DTC P0325, P0327, P0328, P0330, P0332, P0333, P06B6, and P06B7 is not set. If DTC P0335 is set, diagnose that DTC first. Refer to «DTC P0335 or P0336»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) for further diagnosis. If DTC P0325, P0327, or P0328 is set with P06B6, refer to «DTC P0325, P0327, or P0328»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) for further diagnosis. If only DTC P06B6 is set, and no external knock sensor circuit issues exist, replace the K20 engine control module.
Ignition OFF, inspect for the following: The B68 knock sensor for physical damage. A sensor that is dropped or damaged may cause a DTC to set The sensor for proper installation. A sensor that is loose or not at the correct torque may cause a DTC to set. Refer to «Fastener Tightening Specifications (LAF, LEA, or LUK)»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__fastener-tightening-specifications-luk) . The sensor mounting surface for burrs, casting flash, and foreign material The sensor must be clear of hoses, brackets, and engine electrical wiring Loose brackets Loose or broken accessory drive belts, brakcets, components An engine mechanical condition-Refer to «Symptoms - Engine Mechanical»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l) If a condition is found, repair as necessary.
If there is no mechanical condition, test or replace the B68 knock sensor.
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.

Perform the Diagnostic Repair Verification after completing the repair.

«Knock Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming, and setup.

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Knock Sensor 1 Signal	P0327, P06B6	P0325	P0328, P06B6	P0326
Low Reference	P0327		P0328

P0325

Engine speed is between 400-8, 500 RPM.
Engine is running at least 2 s.
The engine coolant temperature (ECT) is warmer than -40°C (-40°F).
The intake air temperature (IAT) is warmer than -40°C (-40°F).
The DTC runs continuously when the above conditions are met.

P0327 and P0328

Engine speed is less than 8, 500 RPM.
The DTCs run continuously when the above condition is met.

P0325

The knock sensor signal circuits are open for least 6 s.

P0327

The knock sensor signal circuits are shorted to ground for least 6 s.

P0328

The knock sensor signal circuits are shorted to voltage for least 6 s.

DTCs P0325, P0327, and P0328 are Type B DTCs.
The ignition timing is retarded to reduce the potential of engine damaging spark knock.

DTCs P0325, P0327, and P0328 are Type B DTCs.

Inspect the knock sensor for physical damage. A knock sensor that is dropped or damaged may cause a DTC to set.
Inspect the knock sensor for proper installation. A knock sensor that is loose or over torqued may cause a DTC to set. The knock sensor should be free of thread sealant.
The knock sensor mounting surface should be free of burrs, casting flash, and foreign material.

Schematic Reference

Connector End View Reference

Electronic Ignition System Description

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Engine running, observe the DTC information with a scan tool. Verify DTC P0325, P0327, P0328, and P06B6 are not set. If DTC P0325, P0327, or P0328 is set with P06B6 continue with Circuit/System Testing. If only DTC P06B6 is set, and no external knock sensor circuit issues exist, replace the K20 engine control module.
Move the related harnesses and connectors for the affected knock sensor circuits while observing the scan tool parameters listed below. The parameters should display NO. Cylinder 1 Knock Detected Cylinder 2 Knock Detected Cylinder 3 Knock Detected Cylinder 4 Knock Detected If the parameters change, repair the wiring or the harness connectors.
Observe the DTC information with a scan tool. DTC P0325, P0327, or P0328 should not set.
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.

Verify the B68 knock sensor is properly tightened, refer to «Fastener Tightening Specifications»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__fastener-tightening-specifications) . If not the specified value, correct the condition as appropriate.
Ignition OFF, disconnect the harness connector at the B68 knock sensor.
Ignition ON, measure for 1-4 V between each of the following circuits and ground on the K20 engine control module side of the harness connector: The signal circuit, terminal A or 1 The low reference circuit, terminal B or 2 If less than the specified range, test the circuits for a short to ground or an open/high resistance. If the circuits test normal, replace the K20 engine control module. If greater than the specified range, test the circuits for a short to voltage. If the circuits test normal, replace the K20 engine control module.
If all circuits test normal, replace the B68 knock sensor.

Perform the Diagnostic Repair Verification after completing the repair.

«Knock Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming, and setup.

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5 V Reference	P0651	P0335	P0335, P0651	P0336
Crankshaft Position Sensor Signal	P0335	P0335	P0335	P0336
Low Reference		P0335		P0336

The crankshaft position sensor circuits consist of an engine control module (ECM) supplied 5 V reference circuit, low reference circuit, and an output signal circuit. The crankshaft position sensor is an internally magnetic biased digital output integrated circuit sensing device. The sensor detects magnetic flux changes of the teeth and slots of a 58-tooth reluctor wheel on the crankshaft. Each tooth on the reluctor wheel is spaced at 60-tooth spacing, with 2 missing teeth for the reference gap. The crankshaft position sensor produces an ON/OFF DC voltage of varying frequency, with 58 output pulses per crankshaft revolution. The frequency of the crankshaft position sensor output depends on the velocity of the crankshaft. The crankshaft position sensor sends a digital signal, which represents an image of the crankshaft reluctor wheel, to the ECM as each tooth on the wheel rotates past the crankshaft position sensor. The ECM uses each crankshaft position signal pulse to determine crankshaft speed and decodes the crankshaft reluctor wheel reference gap to identify crankshaft position. This information is then used to determine the optimum ignition and injection points of the engine. The ECM also uses crankshaft position sensor output information to determine the camshaft relative position to the crankshaft, to control camshaft phasing, and to detect cylinder misfire.

P0335 Condition 1

The starter is engaged and the engine control module detects camshaft position sensor pulses. Or
DTCs P0101, P0102 and P0103 are not set. And
The airflow into the engine is greater than 3 g/s.

Condition 2

DTC P0651 is not set.
The engine is running.

Condition 3

DTCs P0365, P0366, P0641, and P0651, are not set.
The engine is running or the starter is engaged.

P0336 Condition 1

DTCs P0335 or P0651 are not set.
The airflow into the engine is greater than 3 g/s.
Engine speed is greater than 450 RPM.

Condition 2

DTC P0651 is not set.
The engine is running and the starter is not engaged.

Condition 3

The starter is engaged and the engine control module detects camshaft position sensor pulses. Or
DTCs P0101, P0102, and P0103 are not set.
The airflow into the engine is greater than 3 g/s.

Condition 4

DTCs P0365, P0366, P0641, and P0651, are not set.
The engine is running or the starter is engaged.

The DTCs run continuously once the above conditions are met.

P0335 Condition 1

The ECM does not detect a crankshaft position sensor pulse for greater than 4 s.

Condition 2

The ECM does not detect a crankshaft position sensor pulse for greater than 1.0 s.

Condition 3

The ECM does not detect a crankshaft position sensor pulse for 2 failures out of 10 engine revolutions.

P0336 Condition 1

The ECM detects that 20 or more crankshaft resynchronization have occurred within 25.0 s.

Condition 2

The ECM does not detect the synchronization gap on the reluctor wheel for greater than 0.4 s.

Condition 3

The ECM does not detect the synchronization gap on the reluctor wheel for 1.5 s after the starter was engaged.

Condition 4

The ECM detects less than 51 or greater than 65 crankshaft position sensor pulses, during 8 out of 10 engine revolutions based off of camshaft pulses.

DTCs P0335 and P0336 are Type B DTCs.
An engine driveability issue occurs after the first failure.
The camshaft position sensor is used to determine engine position.
The camshaft actuators are commanded to the parked position.

DTCs P0335 and P0336 are Type B DTCs.

Schematic Reference

Connector End View Reference

Electronic Ignition System Description

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool DTC information. DTC P0641 or P0651 should not be set. If the DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P0641 or P0651 for further diagnosis.
Attempt to start the engine. Observe the DTC information with a scan tool. DTC P0335 or P0336 should not set.
Engine idling, observe the scan tool Crankshaft Position Resync Counter parameter. The parameter should always display zero. Move the related harnesses/connectors of the B26 crankshaft position sensor while observing the parameter. Verify the engine does not stumble or stall, and the parameter does not increment.
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.

Ignition OFF, disconnect the harness connector at the B26 crankshaft position sensor.
Ignition OFF, all vehicle systems OFF. It may take up to 2 minutes for all systems to power down. Test for less than 5 ohms between the low reference circuit terminal 2 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 K20 engine control module.
Ignition ON, engine OFF, test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
Test for 4.8-5.2 V between the signal circuit terminal 3 and ground. 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 engine control module. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
Ignition OFF, connect a 3 A fused jumper wire to signal circuit terminal 3.
Ignition ON, momentarily touch the other end of the fused jumper wire to ground repeatedly while monitoring the scan tool Crankshaft Position Sensor Active Counter parameter. The Crankshaft Position Active Counter should increment. If the Crankshaft Position Active Counter does not increment, replace the K20 engine control module.
DTC P0336 should not be set. If DTC P0336 is set, inspect the engine for the conditions listed below and repair as necessary: Excessive play or looseness of the CKP sensor or the reluctor wheel Improper installation of the CKP sensor Foreign material passing between the CKP sensor and the reluctor wheel Damaged reluctor wheel Excessive air gap between the CKP sensor and the reluctor wheel Engine oil for debris Timing chain, tensioner, and sprockets for wear or damage
If all circuits and components test normal, test or replace the B26 crankshaft position sensor.

Perform the Diagnostic Repair Verification after completing the repair.

«Crankshaft Position Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming and setup

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Intake Camshaft Position Sensor 5 V Reference	P0340, P0641	P0340	P0641	P0341
Intake Camshaft Position Sensor Low Reference		P0340
Intake Camshaft Position Sensor Signal	P0340	P0340	P0340
Exhaust Camshaft Position Sensor 5 V Reference	P0641	P0365	P0641	P0366
Exhaust Camshaft Position Sensor Low Reference		P0365
Exhaust Camshaft Position Sensor Signal	P0365	P0365	P0365

The 4 X camshaft position sensor circuits consist of an engine control module (ECM) supplied 5 V reference circuit, low reference circuit, and an output signal circuit. The camshaft position sensor is an internally magnetic biased digital output integrated circuit sensing device. The sensor detects magnetic flux changes of the teeth and slots of a 4-tooth reluctor wheel attached to the camshaft. As each reluctor wheel tooth rotates past the camshaft position sensor, the resulting change in the magnetic field is used by the sensor electronics to produce a digital output pulse. The sensor returns a digital ON/OFF DC voltage pulse of varying frequency, with 4 varying width output pulses per camshaft revolution that represent an image of the camshaft reluctor wheel. The frequency of the camshaft position sensor output depends on the velocity of the camshaft. The ECM decodes the narrow and wide tooth pattern to identify camshaft position. This information is then used to determine the optimum ignition and injection points of the engine. The ECM also uses camshaft position sensor output information to determine the camshaft relative position to the crankshaft, to control camshaft phasing, and for limp-home operation.

The mass air flow (MAF) is greater than 3 grams per second.
The engine is cranking or running.
DTCs P0101, P0102, P0103, P0340 and P0365 run continuously when the above condition is met.

P0340

The ECM does not receive 4 camshaft pulses within 3 s.

P0365

The ECM does not receive 4 camshaft pulses within 3 s.

DTC P0340, and P0365 are Type B DTCs.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Engine idling, observe the scan tool Camshaft Position Active Counter parameter. The parameter should be incrementing.
Engine idling, observe the DTC information with a scan tool. DTC P0340 should not set.
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.

Engine idling, move the related harnesses/connectors of the B23 camshaft position sensor while monitoring the scan tool Camshaft Position Variance parameter. The Camshaft Position Variance parameter should not change when moving the harness/connectors. If the above condition exists, repair the harness/connectors, as necessary.
Ignition OFF, inspect the B23 camshaft position sensor for correct installation. If the B23 camshaft position sensor is loose, inspect the sensor and the O-ring for damage and replace, as necessary.
Ignition OFF, disconnect the harness connector at the B23 camshaft position sensor.
Ignition OFF, all vehicle systems OFF, it may take 2 minutes for all systems to power down, test for less than 5 ohms between the appropriate low reference circuit terminal B and ground. If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
Ignition ON, test for 4.8-5.2 V between the appropriate 5 V reference circuit terminal A and ground. If less than the specified range, test the 5 V reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K20 ECM. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Ignition ON, test for 4.8-5.2 V between the appropriate signal circuit terminal C and ground. If less than the specified range, test the affected signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K20 ECM. If greater than the specified range, test the affected signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Ignition OFF, connect a 3 A fused jumper wire to the B23 camshaft position signal circuit terminal C.
Ignition ON, momentarily touch the other end of the fused jumper wire to the battery negative post. The Camshaft Position Active Counter parameter on the scan tool should increment. If the Camshaft Position Active Counter increments, replace the B23 camshaft position sensor. If the Camshaft Position Active Counter does not increment, replace the K20 ECM.

Note. You must perform the Circuit/System Testing before proceeding with Component Testing.

Inspect the camshaft position sensor for correct installation. Remove the B23 camshaft position sensor from the engine and inspect the sensor and the O-ring for damage. If the sensor is loose, incorrectly installed, or damaged, repair or replace the B23 camshaft position sensor.
Connect the sensor connector to the B23 camshaft position sensor.
Ignition ON, and engine OFF. Observe the Camshaft Position Active Counter parameter on the scan tool. While passing a steel object by the tip of the sensor repeatedly. The Camshaft Position Active Counter parameter should increment. If the parameter does not increment, replace the B23 camshaft position sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Camshaft Position Sensor Replacement - Exhaust»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Camshaft Position Sensor Replacement - Intake»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Intake Camshaft Position Sensor 5 V Reference	P0641	P0340	P0641	P0341
Intake Camshaft Position Sensor Low Reference		P0340
Intake Camshaft Position Sensor Signal	P0340	P0340	P0340
Exhaust Camshaft Position Sensor 5 V Reference	P0641	P0365	P0641	P0366
Exhaust Camshaft Position Sensor Low Reference		P0365
Exhaust Camshaft Position Sensor Signal	P0365	P0365	P0365

P0341 - Near Engine Start, Camshaft Position Fast Event Based Test

The engine is cranking.
The medium resolution is less than or equal to 10 counts.

P0341 - After Engine Start, Camshaft Position Slow Event Based Test

The engine is running.
DTCs P0335, P0336, and P0340 are not set.
DTC P0341 runs continuously when the above conditions are met.

P0366 - Near Engine Start, Camshaft Position Fast Event Based Test

The engine is cranking.
The medium resolution is less than or equal to 10 counts.

P0366 - After Engine Start, Camshaft Position Slow Event Based Test

The engine is running.
DTCs P0335, P0336, and P0365 are not set.
DTC P0366 runs continuously when the above conditions are met.

P0341 - Near Engine Start, Camshaft Position Fast Event Based Test

The ECM detects the incorrect number of camshaft position sensor pulses in 2 revolutions of the crankshaft, which is usually within 1 s.

P0341 - After Engine Start, Camshaft Position Slow Event Based Test

The ECM detects the incorrect number of camshaft position sensor pulses in 2, 000 revolutions of the crankshaft, which is usually within 4 min.

P0366 - Near Engine Start, Camshaft Position Fast Event Based Test

The ECM detects the incorrect number of camshaft position sensor pulses in 2 revolutions of the crankshaft, which is usually within 1 s.

P0366 - After Engine Start, Camshaft Position Slow Event Based Test

The ECM detects the incorrect number of camshaft position sensor pulses in 2, 000 revolutions of the crankshaft, which is usually within 4 min.

DTCs P0341 and P0366 are Type B DTCs.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition OFF, inspect the engine wiring harnesses carrying the camshaft position sensor circuits for the following conditions: Close routing of aftermarket electrical equipment Close to solenoids, motors, and relays Correct any wire harness routing or component placement conditions, if it is determined to be a possible source of electrical interference.
Engine idling, observe the scan tool Camshaft Position Active Counter parameters. Both parameters should be incrementing.
Engine idling, observe the DTC information with a scan tool. DTC P0340 should not set.
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.

Ignition OFF, inspect the B23 camshaft position sensor for correct installation. If the sensor is loose, inspect the sensor and the O-ring for damage, replace as necessary.
Inspect the engine for the following conditions: The engine oil for debris The camshaft reluctor wheel for damage The timing chain, tensioner, and sprockets for wear or damage If debris is found in the engine oil, inspect the internal engine components to determine the cause. Repair or replace any worn or damaged components. Refer to «Camshaft Timing Chain and Sprocket Cleaning and Inspection»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__camshaft-timing-chain-and-sprocket-cleaning) , and «Camshaft Cleaning and Inspection (LAF, LEA, or LUK)»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__camshaft-cleaning-and-inspection-luk) .

Note. You must perform the Circuit/System Testing before proceeding with Component Testing.

Inspect the B23 camshaft position sensor for correct installation. Remove the B23 camshaft position sensor from the engine and inspect the sensor and the O-ring for damage. If the sensor is loose, incorrectly installed, or damaged, repair or replace the B23 camshaft position sensor.
Connect the connector to the B23 camshaft position sensor. Turn ON the ignition, with the engine OFF.
Ignition ON, and engine OFF. Observe the Camshaft Position Active Counter parameter on the scan tool. Pass a steel object by the tip of the sensor repeatedly. The Camshaft Position Active Counter parameter should increment. If the parameter does not increment, replace the B23 camshaft position sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Camshaft Position Sensor Replacement - Exhaust»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Camshaft Position Sensor Replacement - Intake»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
Ignition Voltage	1	2	2
Ignition Coil 1 Control Circuit	P0351	P0351	P0351	P0351	P0351
Ignition Coil 2 Control Circuit	P0352	P0352	P0352	P0352	P0352
Ignition Coil 3 Control Circuit	P0353	P0353	P0353	P0353	P0353
Ignition Coil 4 Control Circuit	P0354	P0354	P0354	P0354	P0354
Low Reference		P0351, P0354	P0351, P0354	P0351, P0354
1. The Engine Cranks But Does Not Run and opens the fuse that supplies voltage to the ignition coils 2. The Engine Cranks But Does Not Run

The ignition system uses individual ignition coil/module assemblies for each cylinder. The engine control module (ECM) controls the individual coils by transmitting timing pulses on the ignition control (IC) circuit of each ignition coil/module to enable a spark event. The ECM monitors each IC circuit for improper voltage levels.

The engine is running.
The ignition voltage is greater than 6 V.
DTCs P0351-P0354 runs continuously when the above condition is met.

The ECM detects an open, short to ground, or a short to voltage on the IC circuit or the ignition coil/module for less than 1 s.

DTCs P0351-P0354 are Type B DTCs.

Schematic Reference

Connector End View Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Engine running, observe the following scan tool control circuit status parameters for the appropriate cylinder T8 ignition coil: Ignition Coil 1-4 Control Circuit Low Voltage Test Status Ignition Coil 1-4 Control Circuit Open Test Status Ignition Coil 1-4 Control Circuit High Voltage Test Status Each parameter should display Not Run or OK.
Engine idling, observe the DTC information with a scan tool. DTC P0351, P0352, P0353, or P0354 should not set.
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.

Ignition OFF, disconnect the harness connector at the appropriate T8 ignition coil.
Ignition OFF, all vehicle systems OFF, it may take up to 2 minutes for all the systems to power down. Test for less than 5 ohms between the ground circuit terminal 1 and ground. If greater than the specified range, repair the ground circuit for an open/high resistance.
Ignition OFF, test for less than 5 ohms between the low reference circuit terminal 2 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.
Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal 4 and ground. If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.
Engine idling at operating temperature, test for 0.200-0.300 V between the appropriate ignition control circuit terminal 3 and ground. If less than the specified range, test the ignition control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM. If greater than the specified range, test the ignition control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
If all circuits test normal, test or replace the T8 ignition coil.

«Ignition Coil Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Note. An ignition control circuit fault condition will result in an engine misfire, and under certain driving conditions could possibly overheat the 3-way catalytic converter.

Install any components or connectors that have been removed or replaced during diagnosis.
Perform any adjustment, programming or setup procedures that are required when a component or module is removed or replaced.
Clear the DTCs.
Turn the ignition OFF for 60 s.
If the repair is related to a DTC, duplicate the Conditions for Running the DTC and use the Freeze Frame/Failure Records, if applicable, to verify the DTC does not reset. If the DTC resets or another DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) and perform the appropriate diagnostic procedure.
To verify that the performance of the catalytic converter has not been affected by the condition that set this DTC, perform the Repair Verification for DTC P0420.

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The secondary air injection system aids in the reduction of hydrocarbon emissions during a cold start. The electric air pump forces fresh air into the exhaust stream in order to accelerate the catalyst operation. A pressure sensor is used to monitor the air flow from the secondary air injection pump. The ECM supplies voltage to the 5-volt reference circuit and supplies a ground to the low reference circuit. The sensor provides a signal voltage to the ECM relative to the pressure changes within the secondary air injection system.

Ignition voltage is supplied to the secondary air injection pump and air injection solenoid valve relays. The ECM controls the relays by grounding the control circuits, which activates the relays. When the relay contacts close, voltage is supplied to the pump and the solenoid valve, which turns the pump on and opens the solenoid valve.

The diagnostic uses 3 phases to test the secondary air injection system

DTCs P0411 and P2430 run during Phase 1
DTCs P2430 and P2440 run during Phase 2
DTC P2444 runs during Phase 3

During phase 1, both the secondary air injection pump and the secondary air injection solenoid valve are activated. Normal secondary air function occurs. Expected system pressure is 8-15 kPa (1.2-2.2 psi) above BARO.

During phase 2, only the secondary air injection pump is activated. The solenoid valve is closed. Pressure sensor performance and solenoid valve deactivation are tested. Expected system pressure is 15-22 kPa (2.2-3.2 psi) above BARO.

During phase 3, neither the secondary air injection pump nor the secondary air injection solenoid valve is activated. secondary air injection pump deactivation is tested. Expected system pressure equals BARO.

DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0114, P0116, P0117, P0118, P0121, P0122, P0123, P0128, P0201, P0202, P0203, P0204, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301, P0302, P0303, P0304, P0351, P0352, P0353, P0354, P0412, P0418, P0420, P0606, P0641, P0651, P1248, P1249, P124A, P124B, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157, P2430, P2431, P2432 or P2433 are not set.
The ignition voltage is between 10-32 V.
The intake air temperature (IAT) is greater than -11°C (+12°F).
The barometric pressure (BARO) is greater than 60 kPa (8.7 psi).
The engine coolant temperature (ECT) is between -11 to +60°C (12-140°F).
The manifold absolute pressure (MAP) sensor is greater than 20 kPa (2.9 psi).
The engine speed is less than 5, 000 RPM.
The mass air flow (MAF) is less than 50 g/s.
Greater than 60 min has elapsed since the last cold start.
The Secondary Air Injection system is commanded ON.
DTC P0411 runs once per trip at start up when the above conditions are met.

The ECM detects that the difference between the predicted system pressure and the actual system pressure is greater than 4.5 kPa (0.65 psi) or less than -7.5 kPa (-1.1 psi) for greater than 7 s. OR
The ECM detects that the average system pressure change is greater than a calibrated threshold for greater than 10 s.

DTC P0411 is a Type B DTC.

A slow responding or skewed secondary air pressure sensor may cause this DTC to set.

Schematic Reference

Connector End View Reference

Secondary Air Injection System Description

Description and Operation

Electrical Information Reference

«Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
«Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
«Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
«Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Ignition ON
Verify that DTC P0412, P0418, P2430, P2431, P2432, P2433, P2440, or P2444 is not set. If any of the DTCs are set Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) If none of the DTCs are set.
Verify the scan tool BARO pressure parameter is within the range specified in the «Altitude Versus Barometric Pressure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__altitude-versus-barometric-pressure) If not within the specified range Refer to «DTC P0106»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) If within the specified range
Verify the scan tool Secondary Air Injection Pressure Sensor and BARO pressure parameters are within 3 kPa (0.4 psi). If not within the specified range Refer to «DTC P2430-P2433»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) If within the specified range
Verify the secondary air injection solenoid valve activates when commanding the Secondary Air Injection Solenoid Valve ON and OFF with a scan tool. If the secondary air injection solenoid valve does not operate as specified Refer to Circuit/System Testing-Secondary Air Injection Solenoid Valve Malfunction below. If the secondary air injection solenoid valve operates as specified
Engine running
Verify the secondary air injection pump turns ON and OFF when commanding the Secondary Air Injection Pump Relay ON and OFF with a scan tool. If the secondary air injection pump does not operate as specified Refer to Circuit/System Testing-Secondary Air Injection Pump Malfunction below. If the secondary air injection pump operates as specified
Verify the scan tool Secondary Air Injection Pressure Sensor parameter increases between 15-22 kPa (2.2-3.2 psi), over the current reading, when the Secondary Air Injection Pump Relay is commanded ON with a scan tool. If not within the specified range Refer to Circuit/System Testing-Secondary Air Injection System Pressure Not In Range below. If within the specified range
Verify the scan tool Secondary Air Injection Pressure Sensor parameter increases between 8-15 kPa (1.2-2.2 psi), over the current reading, when the Secondary Air Injection System is commanded ON with a scan tool. If not within the specified range Refer to Circuit/System Testing-Secondary Air Injection System Pressure Not In Range below. If within the specified range
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/Failure Records data.
Verify the DTC does not set. If the DTC sets Refer to Circuit/System Verification-step 1 below. If the DTC does not set
All OK

Secondary Air Injection Solenoid Valve Malfunction

Ignition OFF, disconnect the KR26 secondary air injection solenoid valve relay.
Verify a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate and the circuit fuse is good Test for less than 2 ohms in the B+ circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF Test for infinite resistance between the B+ circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Disconnect the harness connector at the Q29 secondary air injection solenoid valve. Test for infinite resistance between the control circuit terminal 5 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test or replace the Q29 secondary air injection solenoid valve. If the test lamp illuminates
Disconnect the harness connector at the Q29 secondary air injection solenoid valve.
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 10 ohms between the Q29 secondary air injection solenoid valve ground circuit terminal 4 and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
Connect the harness connector at the Q29 secondary air injection solenoid valve.
Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
Verify the Q29 secondary air injection solenoid valve is activated. If the Q29 secondary air injection solenoid valve does not activate Ignition OFF, disconnect the harness connector at the Q29 secondary air injection solenoid valve. Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the Q29 secondary air injection solenoid valve. If the Q29 secondary air injection solenoid valve activates
Test or replace the KR26 secondary air injection solenoid valve relay.

Secondary Air Injection Pump Malfunction

Ignition OFF, disconnect the KR25 secondary air injection pump relay.
Verify a test lamp illuminates between the B+ circuit terminal 87 and ground. If the test lamp does not illuminate and the circuit fuse is good Ignition OFF Test for less than 2 ohms in the B+ circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF Test for infinite resistance between the B+ circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Disconnect the harness connector at the G21 secondary air injection pump. NOTE: The secondary air injection pump circuit is provided with a flyback diode that may cause the DTC to set if internally shorted. Connect a DMM, set on the diode setting, between the control circuit terminal A and ground. Verify the DMM reading is between 0.5-0.8 V and displays O.L. when the DMM leads are reversed. If less than the specified range, repair the short to ground on the circuit. If within the specified range Test or replace the G21 secondary air injection pump. If the test lamp illuminates
Disconnect the harness connector at the G21 secondary air injection pump.
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 10 ohms between the G21 secondary air injection pump ground circuit terminal B and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
Connect the harness connector at the G21 secondary air injection pump.
Connect a 50 A fused jumper wire between the B+ circuit terminal 87 and the control circuit terminal 30.
Verify the G21 secondary air injection pump is activated. If the G21 secondary air injection pump does not activate Ignition OFF, disconnect the harness connector at the G21 secondary air injection pump. Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, Test or replace the G21 secondary air injection pump. If the G21 secondary air injection pump activates
Test or replace the KR25 secondary air injection pump relay.

Secondary Air Injection System Pressure Not In Range

Verify the following conditions do not exist: Hoses/pipes restricted or blocked Hoses/pipes disconnected Plugged secondary air injection pressure sensor port Damaged secondary air injection check valve If a condition is located Repair or replace the affected component as necessary. If all components test normal
If a condition is not located, and the secondary air injection pump operates with no pressure change, replace the G21 secondary air injection pump.

Relay Test

Ignition OFF, disconnect the appropriate relay.
Test for the following resistance between terminals 85-86. 50-75 ohms-KR25 secondary air injection pump relay 70-110 ohms-KR26 secondary air injection solenoid valve relay If not within the specified range Replace the relay. If within the specified range
Test for infinite resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 If less than infinite resistance Replace the relay. If infinite resistance
Install a 15 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground.
Test for less than 2 ohms between terminals 30 and 87. If 2 ohms or greater Replace the relay. If less than 2 ohms
All OK

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

«Relay Replacement (Within an Electrical Center)»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions__relay-replacement-within-an-electrical-center) , «Relay Replacement (Attached to Wire Harness)»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
«Secondary Air Injection Pipe Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Secondary Air Injection Pump Inlet Hose Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Secondary Air Injection Check Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
«Secondary Air Injection Pump Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)

Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
«Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit	Short to Ground	Open/High Resistance	Short to Voltage
Secondary Air Injection Pump Relay Coil Ignition Supply	P0412, P0418	P0418	P0690
Secondary Air Injection Pump Relay Coil Control	P0418	P0418	P0690, P2431
Secondary Air Injection Solenoid Valve Relay Coil Ignition Supply	P0412	P0412	P0690
Secondary Air Injection Solenoid Valve Relay Coil Control	P0412	P0412	P0412, P0690

The secondary air injection system aids in the reduction of hydrocarbon emissions during a cold start. The electric air pump forces fresh air into the exhaust stream in order to accelerate the catalyst operation. Ignition voltage is supplied directly to the secondary air injection pump relay and secondary air injection solenoid valve relay. The Engine Control Module (ECM) controls the relays by grounding the control circuit with a solid state device called a driver. The ECM monitors the control circuits for open, short to ground or short to a voltage condition.

The ignition voltage is between 10-32 V.
The DTCs run continuously once the above conditions are met.

DTC P0412 or P0418

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 5 s.

DTC P0412 and P0418 are Type B DTCs.

If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Not Run to Malfunction if there is a condition with the circuit or a connection.

Schematic Reference

Connector End View Reference