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Engine Controls/fuel - 2.4l - DTC p0420 to DTC p2635 and Diagnostic Information and Procedures Buick LaCrosse II

Testing & Diagnostics ~36215 words

Diagnostic Instructions

  1. 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.
  2. 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.
  3. «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/System Description

A 3-way catalytic converter controls emissions of hydrocarbons, CO and NOx. The catalyst within the converter promotes a chemical reaction, which oxidizes the hydrocarbons and the CO that are present in the exhaust gas. This process converts the hydrocarbons and the CO into water vapor and CO2, and reduces the NOx, by converting the NOx into nitrogen. The catalytic converter also stores oxygen. The ECM monitors this process by using a Heated Oxygen Sensor (HO2S) that is in the exhaust stream after the 3-way catalytic converter. The HO2S 2 produces an output signal that the ECM uses to calculate the oxygen storage capacity of the catalyst. This indicates the ability of the catalyst to convert the exhaust emissions efficiently. The ECM monitors the efficiency of the catalyst by allowing the catalyst to heat, then wait for a stabilization period while the engine is idling. The ECM then adds and removes fuel while monitoring the HO2S 2. When the catalyst is functioning properly, the HO2S 2 response to the extra fuel is slow compared to the response of the HO2S 1, which is located before the 3-way catalytic converter. When the HO2S 2 response is near that of the HO2S 1, the oxygen storage capability and efficiency of the catalyst may be degraded below an acceptable threshold.

Conditions for Running the DTC

  1. DTC P0010, P0011, P0013, P0014, P0016, P0017, P0030, P0036, P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P013A, P013B, P013C, P013E, P013F, P0140, P0141, P0171, P0172, P0220, P0223, P0300, P0301-P0304, P0443, P0449, P0455, P0496, P0506, P0507, P1101, P1133, P2100, P2102, P2103, P2122, P2123, P2127, P2128, P2135, P2138, P219A, P2232, P2235, P2270, or P2271 is not set.
  2. Before the ECM performs the idle test, the vehicle must be driven under the following conditions: The engine speed is greater than 915 RPM The engine run time is greater than a calibrated value Both conditions exist for greater than 15 s
  3. The throttle is in the rest position.
  4. The intake air temperature (IAT) is between -20 to +250°C (-4 to +482°F).
  5. The ignition voltage is greater than 11 V.
  6. The engine coolant temperature (ECT) is between 40-127°C (104-261°F).
  7. The barometric pressure (BARO) is greater than 70 kPa.
  8. The engine has been idling less than 50 s.
  9. The vehicle speed is less than 2 km/h (1 mph).
  10. The short term fuel trim is learned.
  11. The air flow into the engine is between 3-13 g/s.
  12. The EVAP purge concentration is learned.
  13. The catalytic converter calculated temperature is between 450-950°C (842-1, 742°F).
  14. The engine is operating in Closed Loop.
  15. The transmission is not in P/N (automatic transmission only).

This diagnostic attempts one test during each valid idle period once the above conditions have been met. This diagnostic attempts up to 8 tests during each drive cycle.

Conditions for Setting the DTC

The ECM determines that the efficiency of the catalyst has degraded below a calibrated threshold.

Action Taken When the DTC Sets

DTC P0420 is a Type A DTC.

Conditions for Clearing the DTC

DTC P0420 is a Type A DTC.

Diagnostic Aids

Inspect for the following conditions, which may cause a catalytic converter to degrade

  1. An engine misfire
  2. High engine oil or high coolant consumption
  3. Retarded spark timing
  4. A weak or poor spark
  5. A lean fuel mixture
  6. A rich fuel mixture
  7. A damaged oxygen sensor or wiring harness

Reference Information

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Observe the DTC information with a scan tool. Verify there are no other DTCs 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.
  2. Operate the vehicle within the Conditions for Running the DTC. Observe the scan tool Catalyst Monitor Not At Idle Test Conditions Met parameter. The parameter will change to Yes when the Conditions have been met. If not the specified value, operate the vehicle within the Off Idle Conditions.
  3. When the parameter has changed to Yes and the conditions are safe, stop and idle the vehicle in gear.
  4. Apply the service brake.
  5. Monitor the scan tool Catalyst Monitor Test State parameter. When the parameter indicates Active, the Catalyst Monitor Test is running.
  6. Continue to monitor the parameter. When the parameter indicates Inactive, the Catalyst Monitor Test has completed.
  7. When the test has completed, the Catalyst Monitor Test Counter parameter will increment by one and the Catalyst Monitor Test Result parameter will indicate Pass, Fail or No Decision. If no decision has been made, repeat steps 2-6 until the Test Result parameter indicates Pass or Fail.

Circuit/System Testing

  1. Verify the following conditions do not exist with the catalytic converter: Dents A severe discoloration caused by excessive temperatures Road damage An internal rattle caused by damaged catalyst substrate Restrictions If a condition is found, replace the catalytic converter.
  2. Verify the following conditions do not exist with the exhaust system: Leaks Physical damage Loose or missing hardware If a condition is found, repair the exhaust system.
  3. Verify the following conditions do not exist with the B52B Heated Oxygen Sensor 2. The HO2S is not at the correct torque Damage If a condition is found, repair or replace the B52B Heated Oxygen Sensor 2 as necessary.
  4. If all physical conditions test normal, test or replace the catalytic converter.

Repair Instructions

Note. A new converter with less than 161 kilometers (100 miles) on it may set DTC P0420 due to out-gassing of the internal matting. Operating the vehicle at highway speeds for approximately 1 h may correct the condition.

  1. «Exhaust Leakage»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__exhaust-leakage)
  2. «Restricted Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__restricted-exhaust)
  3. «Heated Oxygen Sensor Replacement - Sensor 2»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  4. «Catalytic Converter Replacement (LUK)»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system)

Repair Verification

  1. Install any components that have been removed or replaced during diagnosis.
  2. Perform any adjustments, programming or setup procedures that are required when a component is removed or replaced.
  3. Clear the DTCs with a scan tool.
  4. Vehicle OFF for 60 s.
  5. Operate the vehicle within the Conditions for Running the DTC. Observe the scan tool Catalyst Monitor Not At Idle Test Conditions Met parameter. The parameter will change to Yes when the Conditions have been met. If not the specified value, operate the vehicle within the Off Idle Conditions.
  6. When the parameter has changed to Yes and the conditions are safe, stop and idle the vehicle in gear.
  7. Apply the service brake.
  8. Monitor the scan tool Catalyst Monitor Test State parameter. When the parameter indicates Active, the Catalyst Monitor Test is running.
  9. Continue to monitor the parameter. When the parameter indicates Inactive, the Catalyst Monitor Test has completed.
  10. When the test has completed, the Catalyst Monitor Test Counter parameter will increment by one and the Catalyst Monitor Test Result parameter will indicate Pass, Fail or No Decision. If no decision has been made, repeat steps 5-9 until the Test Result parameter indicates Pass or Fail.
  11. 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) for further diagnosis.
  1. 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.
  2. 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.
  3. «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 off natural vacuum (EONV) test is the small leak detection diagnostic for the evaporative emission (EVAP) system. This diagnostic tests the EVAP system for a small leak when the key is turned OFF and the correct conditions are met. Heat from the exhaust system is transferred into the fuel tank while the vehicle is operating. When the vehicle is turned OFF and the EVAP system is sealed a change in the fuel tank vapor temperature occurs which results in a corresponding pressure change in the fuel tank vapor space. This change is monitored by the ECM using the fuel tank pressure (FTP) sensor input. With a leak in the system, the amount of pressure change will be less than that of a sealed system.

  1. DTCs P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0222, P0223, P0443, P0446, P0449, P0452, P0453, P0454, P0455, P0461, P0462, P0463, P0464, P0496, P0502, P0503, P0608, P0641, P0651, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138 are not set.
  2. The barometric pressure (BARO) is greater than 70 kPa.
  3. The engine coolant sensor (ECT) is greater than 68°C (154°F)
  4. No fuel filling during the EONV test period.
  5. The fuel level is between 10-90 %.
  6. The start-up engine coolant temperature (ECT) and the start-up intake air temperature (IAT) are between 0-40°C (32-104°F).
  7. The engine run time before engine shut-off was greater than 10 min.
  8. The drive distance before engine shut-off was more than 8.4 km (5.2 mi).
  9. The ignition is OFF.
  10. The ambient air temperature at the end of the drive cycle is between 0-34°C (32-93°F).
  11. DTC P0442 runs once per drive cycle during the hot soak period after the ignition is turned OFF and may require up to 40 min to complete. The controller will not make more than 2 test attempts per day. The time since the last completed EONV test must be at least 17 h.
  1. The ECM detects a leak in the EVAP system that is greater than a calibrated amount.
  2. The ECM must complete several EONV tests before the diagnostic can turn the MIL on or off.

DTC P0442 is a Type A DTC.

DTC P0442 is a Type A DTC.

  1. The EVAP system can be filled with smoke more quickly and completely by opening the system opposite the end where the smoke is injected. When injecting smoke at the service port tool temporarily leave the EVAP vent solenoid valve open until smoke is observed then close the system and continue testing.
  2. To help locate intermittent leaks using the GE 41413-A Evaporative Emissions System Tester (EEST), move all EVAP components while observing smoke with the GE 41413-SPT High Intensity White Light.
  3. Individual components can be isolated and tested using adapters in the GE 41413-300 EVAP Cap and Plug Kit.
  4. A condition may exist where a leak in the EVAP system only exists under a vacuum condition. This type of leak may be detected by using the scan tool Purge/Seal function to create a vacuum in the EVAP system and then observe the FTP parameter for vacuum decay.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. CH 48096 EVAP Service Port Access Tool
  2. GE 41413 A Evaporative Emissions System Tester (EEST)
  3. GE 41413 300 EVAP Cap and Plug Kit
  4. GE 41413 SPT High Intensity White Light

For equivalent regional tools, refer to the appropriate regional tool supplier/catalogue.

Note. Refer to the GE 41413-A EEST operation manual for detailed instructions in Evaporative Emission Control System Description . Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize or produce smoke from a leak. Ensure that the underbody temperature of the vehicle and the tester are similar.

  1. Disconnect the purge tube at the quick connector on the EVAP canister side of the Q12 evaporative emission canister purge solenoid valve and install the CH 48096 EVAP Service Port Access Tool.
  2. Connect the GE 41413-A Evaporative Emissions System Tester (EEST) to the CH 48096 EVAP Service Port Access Tool.
  3. Using a scan tool close the EVAP vent solenoid valve to seal the EVAP system.
  4. Use the flow meter on the GE 41413-A Emissions System Tester (EEST), calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the EVAP system. If a leak is detected, use the GE 41413-A Emissions System Tester (EEST) to apply smoke to the evaporative emission system at the purge tube until the leak is located using the GE 41413-SPT High Intensity White Light.
  1. Seal the EVAP system and use the flow meter on the GE 41413-A Emissions System Tester (EEST), calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the EVAP system.
  2. Clear DTCs.
  1. 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.
  2. 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.
  3. «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

CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Ignition VoltageP0443, P0458P0443
EVAP Canister Purge Valve Control CircuitP0458P0443P0459

The evaporative emission (EVAP) canister purge valve is used to purge fuel vapor from the EVAP canister to the intake manifold. The EVAP canister purge valve is pulse width modulated (PWM). Ignition voltage is supplied directly to the EVAP canister purge valve. The engine control module (ECM) controls the solenoid 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 a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

  1. The engine speed is greater than 80 RPM.
  2. The ignition voltage is between 10-18 volts.
  3. The ECM has commanded the EVAP canister purge valve ON and OFF at least once during the ignition cycle.
  4. The DTCs run continuously once the above conditions are met.

P0443

The ECM detects the EVAP canister purge solenoid control circuit is open. The condition exists for 4 seconds or a cumulative of 30 seconds.

P0458

The ECM detects the EVAP canister purge solenoid control circuit is shorted to ground. The condition exists for 4 seconds or a cumulative of 30 seconds.

P0459

The ECM detects the EVAP canister purge solenoid control circuit is shorted to voltage. The condition exists for 4 seconds or a cumulative of 30 seconds.

DTCs P0443, P0458 and P0459 are Type B DTCs.

DTCs P0443, P0458 and P0459 are Type B DTCs.

If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool EVAP Purge Solenoid Circuit Test Status parameters for the component. A circuit test status parameter changes 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

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON, command the EVAP purge solenoid valve to 50 % with a scan tool. You should hear an audible click.
  2. Engine operating, observe the scan tool EVAP Purge Solenoid Circuit Test Status parameters. Verify the parameters display OK or Not Run.
  3. 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.
  1. Ignition OFF, disconnect the harness connector at the Q12 EVAP purge solenoid Valve.
  2. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal 1 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.
  3. Connect a test lamp between the control circuit terminal 2 and the ignition voltage circuit terminal 1.
  4. Command the EVAP purge solenoid valve to 50 % and then to 0 % with a scan tool. The test lamp should illuminate or flash and then go OFF. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  5. Test for 2.6-4.6 V between the control circuit terminal 2 and the K20 ECM housing. If the voltage is not within the specified range, replace the K20 ECM.
  6. If all circuits test normal, test or replace the Q12 EVAP purge solenoid.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the Q12 EVAP purge solenoid valve. Test for 15-20 ohms between the terminals of the Q12 EVAP purge solenoid valve. If not within the specified range, replace the Q12 EVAP purge solenoid valve.
  2. Measure the resistance between each terminal of the Q12 EVAP purge solenoid valve and the EVAP purge solenoid valve housing. The DMM should display OL. If less than the specified value, replace the Q12 EVAP purge solenoid.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Evaporative Emission Canister Purge Solenoid Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «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
  1. 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.
  2. 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.
  3. «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.

Typical Scan Tool Data

Fuel Tank Pressure Sensor Signal VoltageFuel Tank Pressure
1.5 VAtmospheric Pressure/BARO
Less than 1.5 VPositive Pressure
More than 1.5 VNegative Pressure/Vacuum

This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path that would cause excess amounts of vacuum to be developed in the EVAP system. With the purge valve open and the canister vent valve open, if the EVAP system vacuum goes above a calibrated threshold, the test will fail.

  1. DTCs P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0220, P0222, P0223, P0442, P0443, P0449, P0451, P0452, P0453, P0454, P0464, P0496, P0608, P0609, P0641, P0651, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138 are not set.
  2. The ignition voltage is greater than 11 V.
  3. The barometric pressure (BARO) is more than 70 kPa.
  4. The fuel level is between 10-90 %.
  5. Start up IAT temperature is between 4-30°C.
  6. Start up ECT temperature is less than 35°C.
  7. DTC P0446 runs once per cold start when the above conditions are met.
  1. The fuel tank vacuum is greater than -12 in. H2O vacuum for 5 s. OR
  2. The fuel tank pressure is less than -2.5 in. H2O or more than +5 in. for 60 s after a cold start.

DTC P0446 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0446 is a Type B DTC.

  1. An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP canister vent solenoid valve inlet, or a pinched vent hose. A blockage in the vent system may also cause a poor fuel fill condition.
  2. An EVAP canister filter that is restricted can cause this DTC to set.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «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)
  3. «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

  1. Ignition ON and fuel cap removed, verify that the Fuel Tank Pressure Sensor parameter is between 1.3-1.7 volts. If not within the specified range, go to the Fuel Tank Pressure Sensor section in Circuit/System Testing below.
  2. Install the fuel cap.
  3. With the engine running, the EVAP canister vent solenoid valve open, use a scan tool to command the EVAP canister purge solenoid valve to 100 percent. The fuel tank vacuum should not increase to more than -15 mmHg (-8 inches H2O). If the fuel tank vacuum is greater than the specified range, go to the Restriction section in Circuit/System Testing below.
  4. Using the scan tool, decrease the canister purge duty cycle from 100 percent to 0 percent. The vacuum should decrease to near zero. If the fuel tank vacuum does not return to zero or appears to decrease too slowly go to the Restriction section in Circuit/System Testing below.
  5. 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.

Note. Perform the Circuit/System Verification before proceeding with the Circuit/System Testing.

Restriction

  1. With the engine running, the EVAP canister vent solenoid valve open, and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than -15 mmHg (-8 inches H2O). If the fuel tank vacuum is greater than the specified value, isolate the restriction by disconnecting one component at a time while the EVAP canister purge solenoid valve is commanded to 100 percent and the vent valve is open.
  2. Using the scan tool, decrease the canister purge duty cycle from 100 percent to 0 percent. The vacuum should decrease to near zero. If the fuel tank vacuum does not return to zero, or appears to decrease too slowly, inspect the components in the EVAP vent system for a restriction.

Fuel Tank Pressure Sensor

  1. Ignition OFF, disconnect the harness connector at the fuel tank pressure sensor.
  2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal 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 fuel tank pressure sensor.
  1. «Evaporative Emission Canister Solenoid Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «Evaporative Emission Canister Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  3. «Fuel Tank Pressure Sensor Replacement (NU6)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) , «Fuel Tank Pressure Sensor Replacement (NT7)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  4. «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

With the engine running, the EVAP canister vent solenoid valve open and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than -15 mmHg (-8 inches H2O).

  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Ignition VoltageP0499P0498
EVAP Canister Vent Solenoid Valve Control CircuitP0498P0449P0499

The evaporative emission (EVAP) canister vent valve is used for EVAP system diagnostics. The EVAP canister vent valve is a normally open valve. Battery positive voltage is supplied directly to the EVAP canister vent valve. The engine control module (ECM) controls the solenoid 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 a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. If the ECM detects the control circuit voltage is within a predetermined range when the circuit is commanded OFF, this DTC sets.

  1. The engine speed is greater than 80 RPM.
  2. The ignition voltage is between 10-18 volts.
  3. The ECM has commanded the EVAP canister vent valve ON and OFF at least once during the ignition cycle.
  4. The DTCs runs continuously once the above conditions are met.

P0449

The ECM detects the voltage on the EVAP canister vent valve control circuit is between 2.6-4.6 volts when the driver is commanded OFF. The condition exists for less than 4 seconds or for a cumulative of 30 seconds.

P0498

The ECM detects the voltage on the EVAP canister vent valve control circuit is less than 2.6 volts when the driver is commanded OFF. The condition is present for greater than 4 seconds or for a cumulative of 30 seconds.

P0499

The ECM detects the voltage on the EVAP canister vent valve control circuit is greater than 4.6 volts when the driver is commanded ON. The condition is present for greater than 4 seconds or for a cumulative of 30 seconds.

  1. DTCs P0449, P0498 and P0499 are Type B DTCs.
  2. The EVAP system will only purge during open loop.

DTCs P0449, P0498 and P0499 are Type B DTCs.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Command the EVAP vent solenoid valve ON and OFF with the scan tool. An audible click should be heard when changing between the commanded states.
  2. Start the engine, observe the scan tool EVAP Vent Solenoid Valve Circuit Test Status parameters. The circuit test status parameters should display OK or Not Run.
  3. Engine Idling, observe the DTC information with a scan tool. DTC P0449, P0498, or P0499 should not set.
  4. 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.
  1. Ignition OFF, disconnect the Q13 EVAP vent solenoid valve harness connector.
  2. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal B 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.
  3. Ignition OFF, connect a test lamp between the control circuit terminal A and the ignition voltage circuit terminal B.
  4. Ignition ON, command the scan tool EVAP vent solenoid valve ON and OFF. The test lamp should turn ON and OFF. If the test lamp remains ON all the time, test the control circuit for a short to ground. If circuit/connections test normal, replace the K20 ECM. If the test lamp remains OFF all the time, test the control circuit for a short to voltage or an open/high resistance. If circuit/connections test normal, replace the K20 ECM.
  5. Test for 2.6-4.6 V between the control circuit terminal 2 and ground. If not within the specified range, replace the K20 ECM.
  6. If all circuits/connections test normal, test or replace the Q13 EVAP vent solenoid valve.
  1. Ignition OFF, disconnect the Q13 EVAP vent solenoid valve harness connector.
  2. Test for 20-24 ohms between the terminals of the Q13 EVAP vent solenoid valve. If not within the specified range, replace the Q13 EVAP vent solenoid valve.
  3. Measure the resistance between each terminal of the Q13 EVAP vent solenoid valve and the Q13 EVAP vent solenoid valve housing. The DMM should display OL. If less than the specified value, replace the Q13 EVAP vent solenoid valve.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Evaporative Emission Canister Solenoid Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «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
  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundHigh ResistanceOpenShort to VoltageSignal Performance
FTP Sensor 5 V ReferenceP0452, P0532, P0641P0451P0446, P0452P0453, P0641
FTP Sensor SignalP0452P0451P0452P0453P0451, P0454
FTP Sensor Low ReferenceP0446, P0451P0446P0451
CircuitShort to GroundOpenShort to Voltage
Operating Conditions: Ignition ON, Engine OFF Parameter Normal Range: 1.3-1.7 V
FTP Sensor 5 V Reference0 V0 V4.2-5 V
FTP Sensor Signal0 V0 V5 V
FTP Sensor Low Reference4.5 V

Fuel Tank Pressure Sensor Voltage

The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The engine control module (ECM) supplies a 5 V reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum. The ECM also uses this FTP signal to determine atmospheric pressure for use in the engine-off small leak test, DTC P0442. Before using this signal as an atmospheric reference it must first be re-zeroed.

P0451

  1. DTC P0451 runs only when the engine-off natural vacuum small leak test, P0442, executes.
  2. The number of times this test runs can range from 0-2 per engine-off period. The length of the test can be up to 10 minutes.

P0452 and P0453

DTC P0452 and P0453 run continuously when the ignition is ON.

P0454

  1. DTC P0454 runs only when the engine-off natural vacuum small leak test, P0442, executes.
  2. This test can run once per engine-off period. The length of the test can be up to 10 minutes.
  3. A refueling event is not detected.

P0451

This DTC will set if the controller is unable to re-zero the FTP sensor voltage within a calibrated range during the engine-off small leak test, P0442.

P0452

The FTP sensor voltage is less than 0.1 V for more than 5 s.

P0453

The FTP sensor voltage is more than 4.9 V for more than 5 s.

P0454

If, during the engine-off natural vacuum small leak test, P0442, the ECM detects an abrupt FTP signal change, other than a refueling event, this DTC will set. An abrupt change is defined as a change of 0.45 in H2O in the span of 1 s.

  1. DTCs P0451 and P0454 are Type A DTCs.
  2. DTCs P0452 and P0453 are Type B DTCs.
  1. DTCs P0451 and P0454 are Type A DTCs.
  2. DTCs P0452 and P0453 are Type B DTCs.

P0451 and P0454

  1. A restriction in the EVAP canister or vent lines could prevent fuel vapor pressure from bleeding off fast enough. If the vent system cannot bleed off pressure fast enough, the re-zero procedure may not complete successfully, which could cause this code to set.
  2. Ensure that the reference port on the FTP sensor is unobstructed.
  3. An FTP sensor that is skewed or does not have a linear transition from low to high may cause this code to set. Scan tool output controls, snapshot, and plot functions can help detect erratic sensor response. To test the sensor signal under vacuum conditions, use the Quick Snapshot and the Purge/Seal functions to capture data while commanding purge to 20 %, then plot the data to look for erratic sensor operation. A similar test can be done for the pressure side of the sensor operation by applying pressure with the GE-41413-A system tester while taking a snapshot.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

GE-41413-A Evaporative Emission System Tester (EEST)

  1. Remove the fuel cap.
  2. Ignition ON, engine OFF.
  3. Observe the FTP Sensor parameter with a scan tool.
  4. The FTP Sensor parameter should be 1.3-1.7 V.
  1. Ignition OFF, disconnect the harness connector at the B150 fuel tank pressure sensor.
  2. Ignition OFF. It may take up to for 2 minutes for all vehicle systems to power down. Test for less than 5 ohms of resistance between the low reference circuit terminal 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.
  3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 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.
  4. Verify the scan tool B150 fuel tank pressure sensor parameter is less than 0.2 V. If greater than the specified range, test the signal circuit terminal for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
  5. Install a 3 A fused jumper wire between the signal circuit terminal and the 5 V reference circuit terminal. Verify the scan tool FTP sensor parameter is greater than 4.7 V. If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
  6. If all circuits test normal, test or replace the B150 fuel tank pressure sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Fuel Tank Pressure Sensor Replacement (NU6)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) , «Fuel Tank Pressure Sensor Replacement (NT7)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «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
  1. 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.
  2. 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.
  3. «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 ECM tests the evaporative emission (EVAP) system for a large leak or restrictions to the purge path in the EVAP system. When the enabling criteria has been met the ECM commands the EVAP vent solenoid valve and purge solenoid valve ON, allowing vacuum into the EVAP system. The ECM monitors the fuel tank pressure (FTP) sensor voltage to verify that the system is able to reach a predetermined level of vacuum within a set amount of time.

  1. DTCs P00C8, P00C9, P0068, P16A0, P16A1, P16A2, P16F3, P0068, P0101, P0102, P0103, P010C, P010D, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P160E, P160D, P0191, P0192, P0193, P0220, P0222, P0223, P0443, P0449, P0452, P0453, P0454, P0502, P0503, P0606, P0722, P0723, P1104, P1516, P2100, P2101, P2102, P2103, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2227, P2228, P2229, P2230 is not set
  2. The ignition voltage is between 11-32 V.
  3. The barometric pressure (BARO) is more than 70 kPa.
  4. The fuel level is between 10-90 %.
  5. The cold startup engine coolant temperature (ECT) and the startup intake air temperature (IAT) are equal to or less than 8°C (46°F).
  6. The startup engine coolant temperature (ECT) is less than 35°C (95°F).
  7. The startup intake air temperature (IAT) is between 4-30°C (39-86°F).
  8. DTC P0455 runs once per cold start, for up to 17 min, when the above conditions are met.
  1. The EVAP system is not able to achieve or maintain a calibrated level of vacuum within a set amount of time.
  2. After setting the DTC for the first time, 2 L (0.5 gal) of fuel must be consumed before setting the DTC for the second time.
  3. With a DTC P0455 detected a weak vacuum follow-up test (fuel cap replacement test) will run and passes if tank vacuum is greater than 2.74 kPa (11 in H20). This test will run for a maximum of 21 min. This test runs until it passes.

DTC P0455 is a Type B DTC.

DTC P0455 is a Type B DTC.

  1. Inspect for a loose, missing, damaged, or incorrect fuel fill cap.
  2. Inspect for a damaged fuel filler neck seal surface.
  3. A blockage or restriction in the EVAP purge solenoid valve, purge pipe, EVAP canister, or vapor pipe, can cause this DTC to set.
  4. The EVAP system can be filled with smoke more quickly and completely by opening the system opposite the end where the smoke is injected. Close the system once smoke is observed.
  5. To help locate intermittent leaks using the GE 41413-A Evaporative Emissions System Tester (EEST), move all EVAP components while observing smoke with the J-41413-SPT High Intensity White Light.
  6. Individual components can be isolated and tested using adapters in the J-41413-300 EVAP Cap And Plug Kit.
  7. A condition may exist where a leak in the EVAP system only exists under a vacuum condition. This type of leak may be detected by using the scan tool Purge/Seal function to create a vacuum in the EVAP system and then observe the FTP parameter for vacuum decay.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. CH 48096 EVAP Service Access Port Tool
  2. GE 41413-300 EVAP Cap And Plug Kit
  3. GE 41413-SPT High Intensity White Light
  4. J 41415-30 Fuel Tank Cap Adapter
  5. GE 41413-A Evaporative Emissions System Tester (EEST)
  6. J 41413-311 EVAP Plug
  7. J 41413-VLV EVAP Service Port Vent Fitting

For equivalent regional tools, refer to the appropriate regional tool supplier/catalogue.

Note. Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize or produce smoke from a leak. Refer to the GE 41413-A Evaporative Emissions System Tester (EEST) operation manual for detailed instructions in Evaporative Emission System Diagnosis .

  1. Disconnect the purge tube at the quick connector on the evaporative emission canister side of the Q12 evaporative emission canister purge solenoid valve. Install the CH 48096 EVAP Service Access Port Tool between the disconnected purge tube and the purge solenoid valve. Connect the GE 41413-A Evaporative Emissions System Tester (EEST) to the service access port tool.
  2. Use a scan tool to seal the EVAP system and use the flow meter on the GE 41413-A Evaporative Emissions System Tester (EEST), calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the EVAP system. If a leak is detected, use the GE 41413-A Evaporative Emissions System Tester (EEST) to apply smoke to the EVAP system at the purge tube until the leak is located using the J 41413-SPT High Intensity White Light.
  3. To test for a restriction, connect the GE 41413-A Evaporative Emissions System Tester (EEST) nitrogen/smoke hose to the to the J 41413-311 EVAP plug brass cone adapter. Disconnect the hose at the fuel cap end of the J 41415-30 Fuel Tank Cap Adapter. Connect the J 41413-311 EVAP Plug brass cone adapter to the disconnected hose on the J 41415-30 Fuel Tank Cap Adapter. Install the J 41415-30 Fuel Tank Cap Adapter, filler neck end only, to the vehicle.
  4. Engine to idling, command the Purge/Seal function to seal the system with a scan tool.
  5. Command the EVAP Purge Solenoid Valve to 30 %.
  6. The vacuum/pressure gauge on the GE 41413-A Evaporative Emissions System Tester (EEST) and the FTP parameter on the scan tool should both show vacuum. If the vacuum/pressure gauge shows vacuum, but the FTP parameter does not show vacuum, replace the B150 fuel tank pressure sensor. If neither the FTP parameter nor the vacuum/pressure gauge shows vacuum, repair the restriction in the purge path.
  7. Verify that the vacuum increases to the abort limit on the scan tool or more than 3.2 V, and the values are similar between the scan tool and the vacuum/pressure gauge on the GE 41413-A Evaporative Emissions System Tester (EEST). If the values are not similar, or the voltage did not reach 3.2 V, replace the B150 fuel tank pressure sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. 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.
  2. 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.
  3. «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.

This DTC tests for undesired intake manifold vacuum flow to the evaporative emission (EVAP) system. The engine control module (ECM) seals the EVAP system by commanding the EVAP purge solenoid valve OFF and the vent solenoid valve ON. The ECM monitors the fuel tank pressure (FTP) sensor to determine if a vacuum is being drawn on the EVAP system. If vacuum in the EVAP system is more than a predetermined value within a predetermined time, this DTC sets.

The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP purge and vent solenoid valves.

ECM CommandEVAP Purge Solenoid ValveEVAP Vent Solenoid Valve
ONOpenClosed
OFFClosedOpen
  1. DTCs P00C8, P00C9, P0068, P16A0, P16A1, P16A2, P16F3, P0068, P0101, P0102, P0103, P010C, P010D, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P160E, P160D, P0191, P0192, P0193, P0220, P0222, P0223, P0443, P0449, P0452, P0453, P0454, P0502, P0503, P0606, P0722, P0723, P1104, P1516, P2100, P2101, P2102, P2103, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2227, P2228, P2229, P2230 are not set.
  2. The ignition voltage is between 11-32 V.
  3. The engine OFF time is greater than 8 h
  4. The barometric pressure (BARO) is greater than 70 kPa.
  5. The fuel level is between 10-90 %.
  6. The startup engine coolant temperature (ECT) is less than 35°C (95°F).
  7. The startup intake air temperature (IAT) is between 4-30°C (39-86°F).
  8. DTC P0496 runs once per cold start, for up to 17 min, when the above conditions are met.

The ECM detects more than 10 in H2O vacuum for 5 s during a non-purge condition.

DTC P0496 is a Type B DTC.

DTC P0496 is a Type B DTC.

An intermittent condition could be caused by an improperly installed or damaged EVAP purge solenoid valve or by a temporary blockage or restriction in the EVAP purge solenoid valve.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON, engine OFF, seal the EVAP system using the Purge/Seal function with a scan tool.
  2. Start the engine.
  3. Observe the FTP sensor with a scan tool. The FTP sensor parameter should be less than 1.7 V after 90 s. If the FTP sensor parameter is greater than the specified range, go to Circuit/System Testing below.
  4. 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.
  1. Ignition ON, engine OFF.
  2. Seal the EVAP system using the Purge/Seal function with a scan tool.
  3. Start the engine.
  4. Observe the FTP sensor with a scan tool. The FTP sensor parameter should be less than 1.7 V after 90 s. If the FTP sensor parameter is greater than the specified range, replace the Q12 Evaporative Emission Purge Solenoid Valve.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. 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.
  2. 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.
  3. «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 throttle actuator control (TAC) motor is a DC motor that is part of the throttle body assembly. The TAC motor drives the throttle valve. The engine control module (ECM) controls the TAC motor based on throttle position sensor input. The idle speed is controlled by the ECM based on various inputs. The ECM commands the TAC motor to open or close the throttle valve in order to maintain the desired idle speed.

  1. DTCs P0068, P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0171, P0172, P0201-P204, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268. P0270, P0271, P0300-P0304, P0351-P0354, P0461-P0464, P0496, P0627, P0628, P0629, P0722, P1248, P1249, P124A, P124B, P1516, P2066-P2068, P2147, P2148, P2150, P2151, P2153, P2154, P2156, or P2157 are not set.
  2. The barometric pressure (BARO) is greater than 70 kPa.
  3. The engine coolant temperature (ECT) is greater than 60°C (140°F).
  4. The engine run time is greater than 60 s.
  5. The ignition voltage is greater than 11 V.
  6. The transmission is not changing gears.
  7. The torque converter clutch (TCC) is not changing states.
  8. The intake air temperature (IAT) is warmer than -20°C (-4°F).
  9. The vehicle speed is less than 3 km/h (2 mph).
  10. The commanded engine speed is steady within 25 RPM.
  11. The engine is idling for greater than 5 s.
  12. The DTCs run when the above conditions are met.

P0506

The actual engine speed is 91 RPM less than the desired idle speed for 10 s.

P0507

The actual engine speed is 182 RPM greater than the desired idle speed for 10 s.

DTCs P0506 and P0507 are Type B DTCs.

DTCs P0506 and P0507 are Type B DTCs.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON.
  2. Verify there are no other DTCs 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) for further diagnosis. If no other DTCs are set
  3. 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 %
  4. Engine Idling at the normal operating temperature.
  5. Verify the actual Engine Speed is not 100 RPM less than the Desired Idle Speed. If 100 RPM less than the Desired Idle Speed Refer to Circuit/System Testing below. If 100 RPM greater than the Desired Idle Speed
  6. Verify the actual Engine Speed is not 200 RPM greater than the Desired Idle Speed. If 200 RPM greater than the Desired Idle Speed Refer to Circuit/System Testing below. If 200 RPM less than the Desired Idle Speed
  7. 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.
  8. Verify the DTC does not set. If the DTC sets Refer to Circuit/System Testing below. If the DTC does not set
  9. All OK

Verify none of the following conditions exist

P0506

  1. Restricted exhaust
  2. Mechanical conditions that limits engine speed
  3. Parasitic load on the engine-For example, a transmission condition, a belt driven accessory condition. If a condition is found, repair as necessary.

P0507

  1. Vacuum leaks
  2. A throttle valve that does not close correctly
  3. Verify the correct operation of the crankcase ventilation system. Inspect for the following conditions: The routing of the positive crankcase ventilation (PCV) system Vacuum leaks in the PCV system-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) . If a condition is found, repair as necessary.

Perform the Diagnostic Repair Verification after completing the repair.

  1. 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.
  2. 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.
  3. «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.

During a cold start, the engine control module (ECM) commands dual-pulse mode during Open Loop operation to improve cold start emissions. In dual-pulse mode, the injectors are energized twice during each injection event. As with misfire diagnosis, in dual-pulse mode the ECM monitors the crankshaft position sensor and the camshaft position sensors to calculate crankshaft rotation speed. In normal operation, optimum fuel delivery during dual-pulse mode produces a steady crankshaft rotation speed. If the variations exceed a calibrated value, the code will be set.

  1. DTCs P0010, P0011, P0013, P0014, P0090, P0091, P0092, P00C8, P00C9, P00CA, P0101-P0103, P0106-P0108, P0112, P0113, P0116-P0118, P0122, P0123, P0128, P0171, P0172, P0192, P0193, P0201- P0204, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301-P0304, P0335, P0336, P0351-P0354, P0506, P0507, P0627-P0629, P0722, P0723, P1248, P1249, P124A, P124B, P2122, P2123, P2127, P2128, P2135, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157 are not set.
  2. The catalyst temperature is less than 500°C (932°F).
  3. The engine coolant temperature is warmer than -10°C (14°F).
  4. The barometric pressure is greater than 60 kPa.
  5. The engine speed is between 250-1900 RPM.
  6. The engine is running and a cold start has been detected.
  7. DTC P050D runs once per cold start.

This DTC will set if the ECM detects variations in crankshaft rotation speed caused by the lack of adequate fuel delivery during dual-pulse mode.

  1. DTC P050D is a Type B DTC.
  2. The ECM disables dual pulse mode and energizes the fuel injector as it would for a warm engine.

DTC P050D is a Type B DTC.

  1. This DTC may be set with a misfire DTC, however the existence of this DTC is a higher priority and indicates the condition to diagnose is related to fuel and/or injectors, not the ignition/spark system.
  2. A restricted fuel injector may cause this DTC to set.
  3. High resistance in the circuits of the injectors could set this DTC without setting an injector DTC. Test the injector circuits of the affected cylinders for a high resistance if you suspect a condition.
  4. A drop in system voltage during cold start may set this DTC.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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. Circuit/System Testing requires cold start. Do not start vehicle prior to connecting scan tool and preparing to evaluate the condition during engine crank.

  1. Start the engine and observe the Cylinder 1-4 Current Misfire Counters during first 500 engine cycles. The Cylinder 1-4 Current Misfire Counters should not be incrementing. If the misfire counters are incrementing on one or more cylinders, verify that the following conditions do not exist: 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) .
  2. If all conditions test normal, replace fuel injectors as indicated by high misfire counts.

Note. Repair Verification requires cold start.

  1. Ignition ON, engine OFF, clear the DTCs with a scan tool.
  2. Start the engine.
  3. Verify the DTC does not reset.
  1. 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.
  2. 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.
  3. «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.

This diagnostic applies to internal microprocessor integrity conditions within the engine control module (ECM). This diagnostic also addresses if the ECM is not programmed, or is programmed incorrectly.

P0601, P0602, P0630, P16F3

These DTCs run continuously when the ignition is ON.

P0603, P062F

These DTCs run at power up.

P0604

DTC P0604 runs continuously when the ignition is ON. First memory scan may take up to 30 s.

P0606, P062B

  1. The ignition is ON.
  2. System voltage is greater than 11 V.
  3. These DTCs run continuously when the above conditions are met.

P2610

DTC P2610 runs on ECM power down.

The ECM detects an internal failure or incomplete or incorrect programming.

  1. DTCs P0601, P0602, P0603, P0604, P0606, P062B, P062F, P0630 and P16F3 are Type A DTCs.
  2. DTC P2610 is a Type B DTC.
  1. DTCs P0601, P0602, P0603, P0604, P0606, P062B, P062F, P0630 and P16F3 are Type A DTCs.
  2. DTC P2610 is a Type B DTC.

Low voltage or a momentary loss of power or ground to the ECM may cause a DTC to set. Verify for the following

  1. The battery cables are clean and tight, and the battery is fully charged-Refer to «Battery Inspection/Test»(/buick/lacrosse/ii-2009-2013/remont/charging-system/#battery-charging-system-and-starting-system-except-hybrid) .
  2. The ECM ground circuits do not have an open or high resistance
  3. The ECM power circuits do not have an open, short to ground, or high resistance

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0641, P0651, P0697, or P06A3 does not 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) for further diagnosis.
  2. Observe the DTC information with a scan tool. DTC P0601, P0602, P0603, P0604, P0606, P062B, P062F, P0630, P16F3, or P2610 should not set.
  3. 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.
  1. Ignition ON, clear the DTC information with a scan tool.
  2. Observe the scan tool DTC information. Verify that DTC P0602 or P0630 does not set. If DTC P0602 or P0630 failed this ignition, reprogram the K20 ECM. Refer to «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) . If the DTC resets, replace the K20 ECM.
  3. Observe the DTC information with a scan tool. Verify that DTC P0601, P0603, P0604, P0606, P062B, P062F, P16F3, or P2610 does not set. If a DTC failed this ignition, replace the K20 ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

  1. 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.
  2. 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.
  3. «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 internal fault detection is handled inside the fuel pump control module. No external circuits are involved.

The fuel pump control module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

The fuel pump control module has detected an internal malfunction.

DTC P0601, P0602, P0603, P0604, P0606 and P062F are type A DTCs.

DTC P0601, P0602, P0603, P0604, P0606 and P062F are type A DTCs.

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

Note. This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.

Verify that DTC P0602 is not set.

  1. If the DTC is set, program the K27 fuel pump control module.

Verify that DTCs P0601, P0603, P0604, P0606, and P062F are not set.

  1. If the DTCs are set, program the K27 fuel pump control module. If the DTCs reset, replace the K27 fuel pump control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Fuel Pump EnableP025A, P0628, P069EP025A, P0627, P069EP025A, P0629, P069E

The engine control module (ECM) provides ignition voltage to the fuel pump flow control module whenever the engine is cranking or running. The control module enables the fuel pump flow control module as long as the engine is cranking or running, and ignition system reference pulses are received. While this enable voltage is being received, the fuel pump flow control module supplies a varying voltage to the in-tank fuel pump module in order to maintain the desired fuel line pressure.

  1. The engine speed is greater than 0 RPM.
  2. The ignition voltage is greater than 11 V.
  3. The DTCs run continuously when the conditions above are met.
  1. The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match.
  2. The above condition is met for a minimum of 2.5 s.

DTCs P0627, P0628, and P0629 are Type B DTCs.

DTCs P0627, P0628, and P0629 are Type B DTCs.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Attempt to start the engine. Observe the DTC information with a scan tool. DTC P0627, P0628, or P0629 should not set.
  2. Ignition ON, command the Fuel Pump Enable ON and OFF with a scan tool while observing the following control circuit status parameters: Fuel Pump Enable Circuit Low Voltage Test Status Fuel Pump Enable Circuit Open Test Status Fuel Pump Enable Circuit High Voltage Test Status Each parameter should toggle between OK and Not Run or Not Run and OK.
  3. 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.
  1. Ignition OFF, disconnect the K27 fuel pump control module harness connector.
  2. Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for 0 V on the enable circuit terminal 20 of the fuel pump control module. If greater than the specified value, test for a short to voltage on the enable circuit. If the circuit/connections test normal, replace the K20 ECM.
  3. Ignition ON, command the Fuel Pump Enable ON with a scan tool. Test for B+ on the enable circuit terminal 20 of the fuel pump control module. If less than the specified range, test for a short to ground or an open/high resistance on the enable circuit. If the circuit/connections test normal, replace the K20 ECM.
  4. If all circuits/connections test normal, replace the K27 fuel pump control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

  1. 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.
  2. 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.
  3. «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) has 4 internal 5 V reference circuits. Each internal reference circuit provides external 5 V reference circuits for more than one sensor. A short to ground or short to voltage on one external 5 V reference circuit can affect all the components connected the same internal 5 V reference circuit.

These DTCs run continuously when the ignition voltage is greater than 6.4 V.

The 5 V reference circuit voltage is greater or less than a predetermined threshold.

DTCs P0641, P0651, P0697, and P06A3 are Type A DTCs.

DTCs P0641, P0651, P0697, and P06A3 are Type A DTCs.

DTC P0641

The 5 V reference 1 circuit provides 5 V to the following sensors

  1. Fuel tank pressure sensor
  2. Fuel rail pressure sensor
  3. A/C refrigerant pressure sensor
  4. Exhaust camshaft position sensor
  5. Intake camshaft position sensor

DTC P0651

The 5 V reference 2 circuit provides 5 V to the following sensors

  1. Crankshaft position sensor
  2. Secondary air injection solenoid valve, if equipped

DTC P0697

The 5 V reference 3 circuit provides 5 V to the following sensors

  1. Manifold absolute pressure sensor
  2. Accelerator pedal position sensor 2

DTC P06A3

The 5 V reference 4 circuit provides 5 V to the following sensors

  1. Throttle position sensor
  2. Accelerator pedal position sensor 1

It may be possible to locate the fault by disconnecting one component at a time from the 5 V reference circuit while viewing the 5 V Reference Circuit parameter on the scan tool. The scan tool parameter will change from Malfunction to OK when the source of the fault is disconnected. If all 5 V reference components have been disconnected and a fault is still indicated, the fault may exist in the wiring harness.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON, observe the DTC information with a scan tool. DTC P0641, P0651, P0697, or P06A3 should not set.
  2. Observe the circuit status parameters listed below: 5 V Reference 1 Circuit Status 5 V Reference 2 Circuit Status 5 V Reference 3 Circuit Status 5 V Reference 4 Circuit Status Each parameter should display OK.
  3. 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.
  1. Ignition OFF, disconnect the harness connector of all appropriate sensors for the applicable DTC. Refer to Diagnostic Aids above.
  2. Ignition ON, test for 4.8-5.2 V between one of the affected 5 V reference circuits and ground. If less than the specified range, test for a short to ground on the 5 V reference circuit for each of the affected components. If all circuits test normal, replace the K20 Engine Control Module. If greater than the specified range, test for a short to voltage on the 5 V reference circuit for each of the affected components. If all circuits test normal, replace the K20 Engine Control Module.
  3. Connect each component associated with the affected 5 V reference circuit one at a time while monitoring the appropriate scan tool 5 V Reference 1, 2, 3, or 4 Voltage parameter. The voltage should display 4.8-5.2 V. If not within the specified range when a component is connected, test the signal circuit of that component for a short to voltage. If the circuit tests normal, replace the component.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Accelerator Pedal with Position Sensor Assembly Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  3. «Camshaft Position Sensor Replacement - Intake»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  4. «Camshaft Position Sensor Replacement - Exhaust»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  5. «Crankshaft Position Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  6. «Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  7. «Fuel Tank Pressure Sensor Replacement (NU6)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) , «Fuel Tank Pressure Sensor Replacement (NT7)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  8. «Manifold Absolute Pressure Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  9. «Secondary Air Injection Check Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  10. «Throttle Body Assembly Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  11. «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.
  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
5 V ReferenceP0641P0641, P06A6P0641P06A6
SignalP018CP018B, P018CP018DP018B
Low ReferenceP0641, P06A6P06A6

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 ignition is ON.

The fuel pump control module detects that the fuel pressure 5 V reference is above or below a predetermined voltage threshold.

DTCs P0641 and P06A6 are Type A DTCs.

DTCs P0641 and P06A6 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

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition OFF, disconnect harness connector of the B47 fuel pressure sensor.
  2. Ignition OFF, test for less than 1.0 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 control module.
  3. Ignition ON, test for 4.8-5.2 V between the 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 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 control module.
  4. If all circuits test normal, replace the B47 fuel pressure sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Fuel Pressure Sensor Replacement - Fuel Feed Pipe»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-36l-repair-instructions)
  2. «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, setup, and programming
  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Ignition VoltageP0650P0650
MIL ControlP0650*P0650P0650
* The MIL remains ON

The malfunction indicator lamp (MIL) illuminates to inform the driver that an emission system fault has occurred and the engine control system requires service. Ignition voltage is supplied directly to the MIL and, when the emission fault occurs, the engine control module (ECM) turns the MIL ON by grounding the MIL control circuit. Under normal operating conditions, the MIL should be ON only when the ignition is ON and the engine is OFF.

  1. The engine speed is greater than 80 RPM.
  2. The ignition voltage is between 11-32 V.
  3. The DTC runs continuously when the above conditions are met.

The ECM detects an open, a short to ground, or a short to voltage on the circuit that controls the MIL.

DTC P0650 is a Type B DTC.

DTC P0650 is a Type B DTC.

If the condition is intermittent, move the related harnesses and connectors with the ignition ON and the engine OFF, and with the engine operating while monitoring the scan tool MIL control circuit status parameters. The MIL control circuit status parameters will change from OK or Not Run to Malfunction if there is a condition with the circuit or a connection.

Schematic Reference

  1. «Engine Controls Schematics (LUK)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-wiring-schematic-diagrams)
  2. «Instrument Cluster Schematics»(/buick/lacrosse/ii-2009-2013/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF as commanded.
  2. Command the MIL ON and OFF with a scan tool while observing the following control circuit status parameters: The MIL Control Circuit Low Voltage Test Status The MIL Control Circuit Open Test Status The MIL Control Circuit High Voltage Test Status Each parameter should display OK or Not Run.
  3. Engine running, command the MIL ON and OFF with a scan tool while observing the following control circuit status parameters: The MIL Control Circuit Low Voltage Test Status The MIL Control Circuit Open Test Status The MIL Control Circuit High Voltage Test Status Each parameter should display OK or Not Run.
  4. 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.
  1. Ignition OFF, disconnect the X1 harness connector at the K20 engine control module.
  2. Ignition ON, the malfunction indicator lamp should not illuminate. If the malfunction indicator lamp is illuminated, test the malfunction indicator lamp control circuit terminal 46 X1 for a short to ground. If the circuit tests normal, replace the P16 instrument cluster.
  3. Connect a 3 A fused jumper wire between the malfunction indicator lamp control circuit terminal 46 X1 and ground. The malfunction indicator lamp should illuminate. If the malfunction indicator lamp illuminates, replace the K20 engine control module. If the malfunction indicator lamp does not illuminate, test the malfunction indicator lamp control circuit terminal 46 X1 for a short to voltage or an open/high resistance. If the malfunction indicator lamp control circuit tests normal, test the instrument cluster ignition voltage circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the P16 instrument panel cluster/bulb.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Instrument Cluster Replacement»(/buick/lacrosse/ii-2009-2013/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)
  2. «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, setup, and programming
  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen/High ResistanceShort to Voltage
Relay Coil Supply VoltageP0685, P0689, P1682
Relay Control CircuitP0690P1682P0685, P0689, P1682
Relay Feedback CircuitP0689, P1682P0689, P1682P0690

Engine Controls Ignition Relay

CircuitShort to GroundOpen/High ResistanceShort to Voltage
Ignition 1 Signal, Ignition Main Relay112
1. No Crank condition. 2. Engine continues to operate with ignition OFF.

Ignition Main Relay

CircuitShort to GroundOpenShort to Voltage
Operating Conditions: Component commanded OFF Parameter Normal Range: The following illustrates the normal parameter state with no circuit conditions: Component OFF - OK for Open/Low Voltage test and Not Run for High Voltage test Component ON - Not Run for Open/Low Voltage test and OK for High Voltage test
Battery VoltageMalfunctionMalfunction
Engine Controls Ignition Relay Control CircuitMalfunctionMalfunctionNot Run

Engine Controls Ignition Relay Control Circuit Low Voltage, Open, and High Voltage Test Status - Component Commanded OFF

CircuitShort to GroundOpenShort to Voltage
Operating Conditions: Component commanded ON Parameter Normal Range: The following illustrates the normal parameter state with no circuit conditions: Component OFF - OK for Open/Low Voltage test and Not Run for High Voltage test Component ON - Not Run for Open/Low Voltage test and OK for High Voltage test
Battery VoltageNot RunNot Run
Engine Controls Ignition Relay Control CircuitNot RunNot RunMalfunction

Engine Controls Ignition Relay Control Circuit Low Voltage, Open, and High Voltage Test Status - Component Commanded ON

There are 2 ignition voltage circuits supplied to the engine control module (ECM). One is supplied by the engine controls ignition relay and the other is supplied by the ignition main relay. The ECM monitors and compares the ignition voltage supplied by the two relays.

P0685

The DTC runs continuously when the ignition voltage is greater than 11 V.

P0689

  1. The engine controls ignition relay is commanded ON.
  2. The ignition voltage is greater than 11 V.
  3. DTC P0685 is not set.
  4. The DTC runs continuously when the above conditions are met.

P0690

  1. The engine controls ignition relay is commanded ON.
  2. DTC P0685 is not set.
  3. The DTC runs continuously when the above conditions are met.

P1682

  1. The engine controls ignition relay is commanded ON.
  2. The ignition voltage is greater than 5.5 V.
  3. The DTC runs continuously when the above conditions are met.

P0685

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 2 s.

P0689

The engine controls ignition relay voltage is less than 5 volts for greater than 5 s.

P0690

  1. The ECM detects the engine controls ignition relay feedback circuit is greater than 4 V when the relay is commanded OFF.
  2. The condition is present for greater than 5 s.

P1682

The ECM detects that there is greater than 3 V difference between the ignition main relay signal and the engine controls ignition relay signal circuits for less than 1 s.

  1. DTC P1682 is a Type A DTC.
  2. DTCs P0685 and P0690 are Type B DTCs.
  3. DTC P0689 is a Type C DTC.
  1. DTC P1682 is a Type A DTC.
  2. DTCs P0685 and P0690 are Type B DTCs.
  3. DTC P0689 is a Type C DTC.

The engine controls ignition relay may also be labeled the powertrain relay, the engine control module relay, or the main relay. The ignition main relay may also be labeled the run/crank relay, the ignition 1 relay, the ignition run relay, or the ignition relay.

Schematic Reference

  1. «Engine Controls Schematics (LUK)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-wiring-schematic-diagrams)
  2. «Power Distribution Schematics»(/buick/lacrosse/ii-2009-2013/remont/body-electrical/#wiring-systems-and-power-management-wiring-schematics-and-wiring-harness-routing-diagrams)

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Electrical Center Identification Views»(/buick/lacrosse/ii-2009-2013/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)
  4. «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)
  5. «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

  1. Ignition ON, command the Engine Controls (EC) Ignition Relay ON and OFF with a scan tool while observing the following parameters: Engine Controls Ignition Relay Control Circuit Low Voltage Test Status Engine Controls Ignition Relay Control Circuit Open Test Status Engine Controls Ignition Relay Control Circuit High Voltage Test Status Each parameter should display OK or Not Run in each commanded state.
  2. Ignition ON, observe the DTC information with a scan tool. DTC P0685, P0689, P0690, or P1682 should not set.
  3. Ignition ON, observe the scan tool Ignition 1 Voltage Signal and the Engine Controls Ignition Relay Feedback Signal parameters. There should be less than 3 V difference between the two parameters.
  4. 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.

Note. You must perform the Circuit/System Verification before proceeding with Circuit/System Testing unless sent here from Engine Cranks But Does Not Run.

  1. Ignition OFF, disconnect the KR75 engine controls ignition relay.
  2. Verify that a test lamp illuminates between ground and the relay circuit terminals listed below: Terminal 2 Terminal 3 If the test lamp does not illuminate, test the relay battery voltage circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp does not illuminate between the ignition voltage circuit terminal 5 and ground. If the test lamp illuminates, test the ignition voltage circuit for a short to voltage.
  4. Connect a 20 A fused jumper wire between the relay switch B+ circuit terminal 3 and the relay switch ignition voltage circuit terminal 5.
  5. Ignition ON, observe the scan tool Engine Controls Ignition Relay Feedback Signal parameter. The ECM should communicate, and the parameter should display B+. If not the specified value, or the ECM does not communicate, test the ignition voltage circuit between the engine control module relay and the ECM for a short to ground or for an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.
  6. Ignition OFF, connect a DMM set to the diode setting between control circuit terminal 1 and ground. Verify the DMM displays OL. If not the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
  7. Ignition ON, verify the DMM displays less than 1 V. If not the specified range, test the control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  8. If all circuits test normal, replace the KR75 engine controls ignition relay.
  1. Remove the KR75 engine controls ignition relay.
  2. Test for one of the following resistance specifications between terminals 85 and 86 of the KR75 engine controls ignition relay: 70-110 ohms 200-250 ohms If not within the specified range, replace the KR75 engine controls ignition relay.
  3. Test for infinite resistance between the following terminals of the KR75 engine controls ignition relay: 3 and 1 3 and 5 3 and 2 2 and 5 If not the specified value, replace the KR75 engine controls ignition relay.
  4. Install a 20 A fused jumper wire between relay terminal 2 and 12 V. Install a jumper wire between relay terminal 1 and ground. Test for less than 2 ohms between terminals 3 and 5. If greater than the specified range, replace the KR75 engine controls ignition relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «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)
  2. «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
  1. 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.
  2. 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.
  3. «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 pump control module uses the serial data network to signal the engine control module (ECM) that the fuel pump control module is requesting malfunction indicator lamp (MIL) illumination. A DTC is set in the fuel pump control module, and the request for MIL illumination is sent when the fuel pump control module determines that a failure that affects emissions has occurred in the fuel pump control system. When the ECM receives the message from the fuel pump control module, DTC P069E will set in the ECM.

The ignition is ON, or the engine is running for greater than 3 s.

The fuel pump control module requests the ECM to illuminate the MIL.

  1. DTC P069E is a Type A DTC.
  2. DTC P069E will continue to be current or active as long as the fuel pump control module is requesting MIL illumination.

DTC P069E is a Type A DTC.

Communication codes, U-codes, as well as powertrain codes, P-codes, set in the fuel pump control module will cause the fuel pump control module to request DTC P069E to be set in the ECM.

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

  1. Verify that there are no engine controls or communication DTCs 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 diagnosis of engine control or communications DTCs. If a DTC is not set
  2. Verify that there are no fuel pump control module DTCs 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 diagnosis of fuel pump control module DTCs. If a DTC is not set
  3. 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.
  4. Verify the DTC does not set. If the 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) . If the DTC does not set
  5. All OK.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. 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.
  2. 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.
  3. «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 of the diagnostic category.

Diagnostic trouble code (DTC) P0700 is an informational DTC that indicates that an emission related transmission DTC has set in the transmission control module (TCM). The engine control module (ECM) turns ON the malfunction indicator lamp (MIL) when the TCM sends a message over the serial data circuit requesting MIL illumination. The DTC information for the ECM will only display DTC P0700, and the ECM Freeze Frame/Failure Records data will display the engine operating conditions that were present when the transmission DTC was set. The TCM Freeze Frame/Failure records data is available from the DTC that was set in the TCM.

  1. The ignition is ON or the engine is operating.
  2. DTC P0700 runs continuously.

The ECM receives a serial data message from the TCM requesting the ECM to turn ON the MIL.

DTC P0700 is a Type A DTC.

DTC P0700 is a Type A DTC.

Communication codes, U-codes, as well as powertrain codes, P-codes, set in the TCM can cause the TCM to request DTC P0700 to be set in the ECM.

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

  1. Verify that there are no engine controls or communication DTCs 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 diagnosis of engine control or communications DTCs. If a DTC is not set
  2. Verify that there are no transmission control module DTCs 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 diagnosis of transmission control module DTCs. If a DTC is not set
  3. 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.
  4. Verify the DTC does not set. If the 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) . If the DTC does not set
  5. All OK.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. 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.
  2. 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.
  3. «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.

This DTC indicates the hybrid powertrain control module has set an emission related hybrid powertrain DTC. The hybrid powertrain control module sends a message via the serial data circuit to the engine control module (ECM) requesting illumination of the malfunction indicator lamp (MIL). When the ECM receives the message, DTC P0AC4 will set. The DTC information for the ECM will only display DTC P0AC4, but the freeze frame/failure records data may display the hybrid powertrain DTC that set.

  1. The ignition is ON for greater than 3 s.
  2. This DTC runs continuously when the above condition is met.

The hybrid powertrain control module has set an emission related DTC.

DTC P0AC4 is a Type A DTC.

DTC P0AC4 is a Type A DTC.

Description and Operation

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Note. Correct any engine control DTCs before diagnosing hybrid powertrain control module DTCs.

  1. DTC P0AC4 is an informational DTC. If there are no other engine control DTCs 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 diagnosis of hybrid powertrain control module DTCs.
  2. 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.

  1. 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.
  2. 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.
  3. «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) 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.

The engine is running.

The fuel pump control module detects an over-temperature fault.

DTCs P064A and P1255 are Type A DTCs.

DTCs P064A and P1255 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

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Verify that DTC P0231, P0232 or P023F are not set. If any of those codes are set, refer to «DTC P0231, P0232, or P023F»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-36l-dtc-p0010-to-dtc-p0390) .
  2. Ensure that the entire undercarriage of the vehicle is clean, especially around the area where the K27 fuel pump control module is located. Clear all codes from the K27 fuel pump control module and test drive the vehicle. Verify that DTC P1255 or P064A do not set. If DTC P1255 or P064A reset, replace the K27 fuel pump control module.

Perform the Diagnostic Repair Verification after completing the repair.

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

  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Ignition Coil Supply Voltage Bank 1P0201, P0203, P0205, P0300, P0351, P0353, P0355, P135AP0201, P0203, P0205, P0300, P0351, P0353, P0355, P135A

The ignition system on this engine uses an individual module/coil for each cylinder. The engine control module (ECM) monitors the ignition voltage from the fuse of each bank of coils to the ECM. The ECM uses this information to determine if the misfire is ignition coil voltage related.

  1. The ignition is ON.
  2. The ignition module supply voltage is less than 2.5 V.
  3. The DTCs run continuously when the above condition is met.

The ECM detects a fault in an ignition coil control circuit for 50 out of 63 samples. Each sample runs on a 6.25 ms loop.

DTC P135A is a Type A DTC.

DTC P135A is a Type A DTC.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Electronic Ignition System Description»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-description-and-operation__electronic-ignition-system-description)
  2. «Engine Control Module Description»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-description-and-operation__engine-control-module-description)

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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

With the ignition ON, observe the Ignition Coil Supply Voltage Bank 1 parameter for each cylinder.

The parameter should display ON.

Note. The ignition circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition circuit.

  1. Ignition OFF, disconnect the harness connector at the appropriate T8 ignition coil.
  2. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal D and ground of each T8 ignition coil. If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, with the ignition OFF, disconnect the harness connector at each T8 ignition coil and monitor the fuse while individually connecting each T8 ignition coil. If the fuse opens, replace the appropriate T8 ignition coil.
  3. Ignition OFF, disconnect the K20 ECM harness connector X1.
  4. Ignition ON, connect a test lamp between the X1 67 ignition voltage circuit and ground. The test lamp should illuminate on each circuit. If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.
  5. If all circuits/connections test normal, replace the K20 ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Ignition Coil Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for K20 ECM replacement, setup, and programming
  1. 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.
  2. 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.
  3. «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 catalytic converter must be warmed to efficiently reduce the emissions. The cold start strategy is to reduce the amount of time it takes to warm the catalytic converter. During a cold start, the engine idle speed is elevated and spark timing is retarded to allow the catalyst to warm quickly. This diagnostic monitors the following to build an exhaust energy model

  1. Engine speed
  2. Spark advance
  3. Throttle position
  4. Engine airflow
  5. Engine coolant temperature
  6. Engine run time
  7. Park/Neutral position
  8. Vehicle speed

The actual model is then compared to the expected exhaust energy model.

  1. The engine is running, and a cold start has been detected.
  2. The vehicle speed is less than 2 km/h (1 mph).
  3. The catalyst temperature is greater than 1, 000°C (1, 832°F).
  4. The coolant temperature is greater than 56°C (133°F).
  5. The engine run time is greater than 18 s.
  6. The engine is at idle with no input from the accelerator pedal for greater than 5 s.
  7. DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0220, P0222, P0223, P0201, P0202, P0203, P0204, P0300, P0335, P0336, P0351, P0352, P0353, P0506, P0507, P0601, P0602, P0603, P0604, P0606, P0607, P062F, P0641, P0651, P1516, P1682, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, P2176, P2610 are not set.
  8. This DTC runs within 15 seconds within the first 2 minutes of start-up. This diagnostic runs once per trip when a cold start has been determined.

The actual exhaust energy model does not match the expected exhaust energy model.

DTC P1400 is a Type A DTC.

DTC P1400 is a Type A DTC.

Any loading of the engine that lowers engine RPM, such as partial application of the clutch, A/C cycling, etc. during the first 120 seconds of the engine run time may set this DTC.

  1. Allow the engine to cool until the catalyst temperature is less than 500°C (932°F) and the engine coolant is greater than -10°C (+14°F).
  2. Idle the engine for greater than 2 minutes.
  3. Observe the scan tool DTC information. DTC P1400 should not set.
  4. 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.
  1. Inspect the air intake system for the following: Modified, damaged, or restricted Dirty or deteriorating air filter element Crankcase ventilation system for correct operation. Water intrusion Vacuum leak and other unmetered air downstream of the MAF sensor Intake manifold leak
  2. Inspect the exhaust system for the following: Water intrusion Exhaust leak Damaged, restricted, modified or enhanced exhaust system.
  3. Inspect the engine mechanical for items that could alter the air flow into the combustion chamber.
  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundHigh ResistanceOpenShort to VoltageSignal Performance
TAC Motor Control ClosedP1516, P2101, P2176P1516, P2101, P2176P1516, P2101, P2176P0690, P1516, P2101, P2176P1516, P2101, P2176
TAC Motor Control OpenP1516, P2101, P2119, P2176P1516, P2101, P2176P1516, P2101, P2176P0690, P1516, P2101, P2176P1516, P2101, P2176

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.

The ECM controls the throttle valve by applying a varying voltage to the control circuits of the throttle actuator control (TAC) motor. The ECM monitors the duty cycle that is required to actuate the throttle valve. The ECM monitors the throttle position sensor signal/serial data circuit to determine the actual throttle valve position.

P1516

  1. The run/crank or powertrain relay voltage is greater than 6.4 V and reduced power is not active.
  2. DTC P1516 runs continuously when the above conditions are met.

P2101

  1. DTC P1682 is not set.
  2. The run/crank or powertrain relay voltage is greater than 6.4 V and reduced power is not active.
  3. The engine is running or the following conditions are met: The engine is not running. The ignition voltage is greater than 11 V. The TAC system is not in the Battery Saver mode. The ECM is commanding the throttle. The ECM has learned the minimum throttle position.
  4. DTC P2101 runs continuously when the above conditions are met.

P2119

  1. DTCs P0122, P0123, P0222, P0223, or P06A3 is not set.
  2. The run/crank or powertrain relay voltage is greater than 6.4 V and reduced power is not active.
  3. The system is not in the Battery Save mode.
  4. The ECM is not commanding the throttle.
  5. DTC P2119 runs continuously when the above conditions are met.

P2176

  1. The run/crank or powertrain relay voltage is greater than 6.4 V and reduced power is not active.
  2. DTC P2176 runs continuously when the above conditions are met.

P1516

The ECM detects an unstable throttle position for greater than 1 s.

P2101

  1. The ECM detects the actual throttle position does not match the predicted throttle position for greater than 1 s. Or
  2. The ECM detects the throttle control is driving the throttle in the incorrect direction or exceed the reduced power limit.

P2119

The ECM determines that the throttle blade did not return to the rest position within 1 s.

P2176

The ECM detects that both throttle position sensors were greater than a predetermined voltage during the minimum throttle learn procedure for greater than 2 s.

  1. DTCs P1516, P2101, and P2176 are type A DTCs.
  2. DTC P2119 is a type C DTC.
  3. The ECM commands the TAC system to operate in the Reduced Engine Power mode.
  4. A message center or an indicator displays Reduced Engine Power.
  5. Under certain conditions, the control module commands the engine OFF.
  1. DTCs P1516, P2101, and P2176 are type A DTCs.
  2. DTC P2119 is a type C DTC.
  1. Inspect for a condition in which the throttle valve may have been held open. For example, ice may have formed in the throttle bore causing the throttle valve not to close.
  2. A high resistance condition on the throttle position and throttle actuator control circuits could cause a DTC to set.
  3. A low battery condition may cause a DTC to set.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON.
  2. Verify DTC P0121, P0122, P0123, P0222, P0223, P0562, P0621, P0622, or P2135 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
  3. 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 %
  4. Clear the DTCs with a scan tool.
  5. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down.
  6. Ignition ON.
  7. Verify the scan tool TAC Motor parameter displays Enabled. If Disabled Refer to Circuit/System Testing below. If Enabled
  8. Verify DTC P1516, P2101, P2119, or P2176 is not set. If any of the DTCs are set Refer to Circuit/System Testing below. If none of the DTCs are set
  9. Verify the scan tool TAC Motor parameter displays Enabled while performing the Throttle Sweep Test with a scan tool. If Disabled NOTE: Before replacing the throttle body assembly, make sure the TAC motor control circuits are not shorted to B+. Test or replace the Q38 throttle body assembly. If Enabled
  10. 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.
  11. Verify the DTC does not set. If the DTC sets Refer to Circuit/System Testing below. If the DTC does not set
  12. All OK
  1. Ignition OFF.
  2. Verify the conditions listed below do not exist with the Q38 throttle body assembly: A throttle blade that is not in the rest position A throttle blade that is binding open or closed A throttle blade that is free to move open or closed without spring pressure If a condition is found Test or replace the Q38 throttle body assembly. If a condition is not found
  3. Ignition OFF.
  4. Disconnect the harness connector at the Q38 throttle body assembly, ignition ON.
  5. Verify that a test lamp does not illuminate continuously between each motor control circuit listed below and ground. TAC Motor Control Open circuit terminal 1 TAC Motor Control Closed circuit terminal 2 If the test lamp illuminates continuously Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON Test for less than 1 V between the control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If the test lamp is always OFF
  6. Verify that a test lamp does not illuminate between each motor control circuit listed below and B+. TAC Motor Control Open circuit terminal 1 TAC Motor Control Closed circuit terminal 2 If the test lamp illuminates Ignition OFF, disconnect the harness connector at the K20 engine control module. Test for infinite resistance between the control circuit 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 the test lamp is always OFF
  7. Ignition OFF, set the DMM to the 40 V scale or higher, select the Min/Max Recording Mode, and set the Peak Min/Max response time to 1 ms or faster.
  8. Verify the Max voltage is within 3 V of B+ while using DMM Min/Max Recording Mode function on each control circuit listed below as the ignition is turned ON. TAC Motor Control Open circuit terminal 1 TAC Motor Control Closed circuit terminal 2 If not within 3 V of B+ Ignition OFF, disconnect the harness connector at the K20 engine control module. 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, replace the K20 engine control module. If within 3 V of B+
  9. Test or replace the Q38 throttle body assembly.
  1. «Throttle Body Assembly Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «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
  1. Install any components that have been removed or replaced during diagnosis.
  2. Perform any adjustments, programming or setup procedures that are required when a component is removed or replaced.
  3. Clear the DTCs with a scan tool.
  4. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down.
  5. Ignition ON.
  6. Verify the scan tool TAC Motor parameter displays Enabled while performing the Throttle Sweep Test with a scan tool. If Disabled Test or replace the Q38 throttle body assembly. If Enabled
  7. 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 DTCs set
  8. All OK
  1. 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.
  2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for a overview of the diagnostic approach.
  3. «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 hybrid powertrain control module is constantly sending serial data messages to the ECM regarding the operating state of the powertrain propulsion system. These messages are sent in a continuously repeating series of rolling counts with associated password protect samples and each count/sample is assigned a value. The ECM uses the values, during a propulsion system mode shift, to determine when and at what RPM to idle the internal combustion engine. When the ECM determines that too many of the counts/samples contain an error value, the ECM sets DTC P15F9.

  1. DTC U1817 is not set.
  2. The engine run time is greater than 0.5 s.
  3. No other CAN errors are present.
  4. The DTC runs continuously when the above conditions are met.

The ECM detects that 10 of 16 counts/samples contain an error value.

DTC P15F9 is a Type B DTC

DTC P15F9 is a Type B DTC.

An intermittent fault in the CAN circuits will cause the ECM to set DTC P15F9.

Description and Operation

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

  1. DTC P15F9 is an informational DTC. If there are no other engine control DTCs 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 diagnosis of hybrid powertrain control module DTCs.
  2. 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.

  1. 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.
  2. 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.
  3. «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.

This diagnostic applies to internal microprocessor integrity conditions within the engine control module (ECM) or an out of range high pressure fuel pump actuator current.

  1. DTCs P0016, P0017, P0090, P0091, P0092, P00C8, P00C9, P00CA, P0112, P0113, P0116, P0117, P0118, P0128, P0192, P0193, P0335, P0336, P0340, P0341, P0365, P0366, P0627-P0629, P1682 are not set.
  2. The engine is running.
  3. The ignition voltage is greater than 11 V.
  4. The low side fuel pressure is greater than 275 kPa (40 psi).
  5. DTC P163A runs continuously when the conditions are met for greater than 500 mS.

The ECM detects a condition with the integrated circuits of the high pressure fuel pump actuator driver module or the ECM detects that the current used to drive the high pressure fuel pump actuator is out of range for greater than 4 s.

DTC P163A is a Type B DTC.

DTC P163A is a Type B DTC.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition OFF, disconnect the harness connector at the G18 high pressure fuel pump.
  2. Test for 9-11 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. If all circuits and the high pressure fuel pump test normal, replace the K20 ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Fuel Pump Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__fuel-pump-replacement)
  2. «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, setup, and programming
  1. 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.
  2. 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.
  3. «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 Description

Fuel trim bias is used to keep the post catalyst air/fuel ratio within a predetermined range. This allows optimal catalyst efficiency under various operating conditions. The engine control module (ECM) constantly monitors how lean or rich the fuel trim bias is commanded, to determine if the fuel trim bias is greater than a calibrated amount.

  1. DTC P0016, P0017, P0018, P0019, P0053, P0054, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0121, P0122, P0123, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P013A, P013B, P013E, P013F, P0140, P0141, P0178, P0179, P0201, P0202, P0203, P0204, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0301, P0302, P0303, P0304, P0340, P0341, P0345, P0346, P0365, P0366, P0390, P0391, P0442, P0443, P0446, P0449, P0452, P0453, P0455, P1221, P1248, P1249, P124A, P124B, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157, P219A, P2227, P2228, P2229, P2230, P2269, P2270, P2271, P2440, P2444, or P2A00 is not set.
  2. The barometric pressure (BARO) is greater than 70 kPa (10.2 PSI).
  3. The manifold absolute pressure (MAP) is between 0-200 kPa (0-29 PSI).
  4. The intake air temperature (IAT) is between -20 and +200°C (-4 and +392°F).
  5. The engine coolant temperature is greater than -20°C (-4°F).
  6. The engine is in Closed Loop status.
  7. The fuel control intrusive diagnostics are not active.
  8. The engine is operating under light acceleration, heavy acceleration, deceleration, or cruise.
  9. DTC P2096 runs continuously when the conditions above have been met for greater than 40 seconds.

The lean correction limit for a condition causing a rich air/fuel ratio has been exceeded.

  1. DTCs P2096 is a Type B DTC.
  2. The ECM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the ECM stores this information in the Failure records. If the diagnostic reports a failure on the second ignition cycle, the ECM records the operating conditions at the time of the failure. The ECM writes the operating conditions to the Freeze Frame and updates the Failure records. The ECM illuminates the malfunction indicator lamp (MIL) when one of the following occurs: The ECM detects the same fuel trim failure during 2 consecutive trips. The ECM detects any fuel trim failure during any subsequent trip if the conditions at the time of failure meet the following criteria: The engine load is within 20 percent of the previous test that failed. The engine speed is within 375 RPM of the previous test that failed. The engine coolant temperature is in the same range of the previous test that failed.
  1. DTCs P2096 is a Type B DTC.
  2. The ECM turns OFF the malfunction indicator lamp (MIL) at the beginning of the fourth ignition cycle, after 3 ignition cycles that the diagnostic runs and does not fail.
  3. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  1. It is very unlikely that an HO2S will cause this DTC to set without the occurrence of circuit related HO2S DTCs. Do not replace an HO2S to address this DTC without first performing all the steps in Circuit/System Verification.
  2. The post catalyst fuel trim diagnostic is very sensitive to heated oxygen sensor (HO2S) design. A non-OE sensor or an incorrect part number may cause a DTC to set.
  3. Certain aftermarket air filters may cause a DTC to set.
  4. Certain aftermarket air induction systems or modifications to the air induction system may cause a DTC to set.
  5. Certain aftermarket exhaust system components may cause a DTC to set.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON, observe the scan tool DTC information. Verify there is no other HO2S or fuel trim DTC set. If any other HO2S or fuel trim 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) .
  2. Verify that none of the following conditions exist: The air intake duct for being collapsed or restricted. The air filter for biting dirty or restricted. Objects blocking the throttle body. Excessive fuel in the crankcase. Change engine oil as necessary. 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) . Excessive fuel system 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 that is contaminated-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) . Fuel saturation of the evaporative emissions (EVAP) canister Stuck open or leaking EVAP purge valve Restricted exhaust-Refer to «Symptoms - Engine Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__symptoms-engine-exhaust) . Incorrect PCV system operation-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) . If you find any of the above conditions, repair as necessary.
  3. 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.

  1. 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.
  2. 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.
  3. «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.

Fuel trim bias is used to keep the post catalyst air/fuel ratio within a predetermined range. This allows optimal catalyst efficiency under various operating conditions. The engine control module (ECM) constantly monitors how lean or rich the fuel trim bias is commanded, to determine if the fuel trim bias is greater than a calibrated amount.

  1. DTC P0016, P0017, P0018, P0019, P0053, P0054, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0121, P0122, P0123, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P013A, P013B, P013E, P013F, P0140, P0141, P0178, P0179, P0201, P0202, P0203, P0204, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0301, P0302, P0303, P0304, P0340, P0341, P0345, P0346, P0365, P0366, P0390, P0391, P0442, P0443, P0446, P0449, P0452, P0453, P0455, P1221, P1248, P1249, P124A, P124B, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157, P219A, P2227, P2228, P2229, P2230, P2269, P2270, P2271, P2440, P2444, or P2A00 is not set.
  2. The barometric pressure (BARO) is greater than 70 kPa (10.2 PSI).
  3. The manifold absolute pressure (MAP) is between 0-200 kPa (0-29 PSI).
  4. The intake air temperature (IAT) is between -20 and +200°C (-4 and +392°F).
  5. The engine coolant temperature is greater than -20°C (-4°F).
  6. The engine is in Closed Loop status.
  7. The fuel control intrusive diagnostics are not active.
  8. The engine is operating under light acceleration, heavy acceleration, deceleration, or cruise.
  9. DTC P2097 runs continuously when the conditions above have been met for greater than 40 seconds.

The rich correction limit for a condition causing a lean air/fuel ratio has been exceeded.

  1. DTCs P2097 is a Type B DTC.
  2. The ECM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the ECM stores this information in the Failure records. If the diagnostic reports a failure on the second ignition cycle, the ECM records the operating conditions at the time of the failure. The ECM writes the operating conditions to the Freeze Frame and updates the Failure records. The ECM illuminates the malfunction indicator lamp (MIL) when one of the following occurs: The ECM detects the same fuel trim failure during 2 consecutive trips. The ECM detects any fuel trim failure during any subsequent trip if the conditions at the time of failure meet the following criteria: The engine load is within 20 percent of the previous test that failed. The engine speed is within 375 RPM of the previous test that failed. The engine coolant temperature is in the same range of the previous test that failed.
  1. DTCs P2097 is a Type B DTC.
  2. The ECM turns OFF the malfunction indicator lamp (MIL) at the beginning of the fourth ignition cycle, after 3 ignition cycles that the diagnostic runs and does not fail.
  3. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  1. It is very unlikely that an HO2S will cause this DTC to set without the occurrence of circuit related HO2S DTCs. Do not replace an HO2S to address this DTC without first performing all the steps in Circuit/System Verification.
  2. The post catalyst fuel trim diagnostic is very sensitive to heated oxygen sensor (HO2S) design. A non-OE sensor or an incorrect part number may cause a DTC to set.
  3. An exhaust system leak that may not be audible can set this DTC.
  4. Certain aftermarket air filters may cause a DTC to set.
  5. Certain aftermarket air induction systems or modifications to the air induction system may cause a DTC to set.
  6. Certain aftermarket exhaust system components may cause a DTC to set.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON, observe the scan tool DTC information. Verify there is no other HO2S or fuel trim DTC set. If any other HO2S or fuel trim 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) .
  2. Verify that none of the following conditions exist: Exhaust system leaks-Refer to «Symptoms - Engine Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__symptoms-engine-exhaust) . Vacuum hoses for splits, kinks, and proper connections Insufficient fuel in the tank The air induction system and the air intake ducts for leaks or for a missing air filter element A cracked evaporative canister Evaporative pipes plugged, 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) . Engine vacuum leaks Low fuel system 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 that is contaminated-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) . Lean 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) . If you find any of the above conditions, repair as necessary.
  3. 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.

  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundHigh ResistanceOpenShort to VoltageSignal Performance
Accelerator Pedal Position (APP) Sensor 1 5 V Reference CircuitP06A3P2138P2122P06A3P2138
Accelerator Pedal Position (APP) Sensor 2 5 V Reference CircuitP0108, P0107, P0697P2138P2127P0106, P0108, P0697P2138
Accelerator Pedal Position (APP) Sensor 1 SignalP2122P2138P2122P2123, P2138P2138
Accelerator Pedal Position (APP) Sensor 2 SignalP2127P2138P2127P2128, P2138P2138
Accelerator Pedal Position (APP) Sensor 1 Low ReferenceP2138P2123P2138
Accelerator Pedal Position (APP) Sensor 2 Low ReferenceP2138P2128P2138
CircuitShort to GroundOpenShort to Voltage
Operating Conditions: The engine is operating at idle. Parameter Normal Range: APP Sensor 1 0.88-1.08 V
APP Sensor 1 5 V Reference0.00 V0.00 V2-5 V
APP Sensor 1 Signal0.00 V0.00 V4-5 V
APP Sensor 1 Low Reference4-5 V

APP Sensor 1

CircuitShort to GroundOpenShort to Voltage
Operating Conditions: The engine is operating at idle. Parameter Normal Range: APP Sensor 2 0.39-0.59 V
APP Sensor 2 5 V Reference0.00 V0.00 V1-2 V
APP Sensor 2 Signal0.00 V0.00 V2-5 V
APP Sensor 2 Low Reference4-5 V

APP Sensor 2

The accelerator pedal assembly contains 2 accelerator pedal position (APP) sensors. The APP sensors are mounted to the accelerator pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to pedal position. The engine control module (ECM) supplies each APP sensor with a 5 V reference circuit, a low reference circuit, and a signal circuit.

Both the APP sensors 1 and 2 signal percentages increase as the pedal is depressed, from approximately 0 percent at rest to above 95 percent when fully depressed.

P2122, P2123, P2127, or P2128

  1. DTC P06A3 or P0697 are not set.
  2. The ignition is ON or the engine is operating.
  3. The ignition voltage is greater than 6 V.
  4. The ECM is not commanding reduced power.
  5. The DTCs run continuously when the above conditions are met.

P2138

  1. DTCs P06A3, P0697, P2122, P2123, P2127, or P2128 are not set.
  2. The ignition is ON or the engine is operating.
  3. The ignition voltage is greater than 6 V.
  4. The ECM is not commanding reduced power.
  5. The DTC runs continuously when the above conditions are met.

P2122

The ECM detects that the APP sensor 1 voltage is less than 0.46 V for greater than 1 s.

P2123

The ECM detects that the APP sensor 1 voltage is greater than 4.7 V for greater than 1 s.

P2127

The ECM detects that the APP sensor 2 voltage is less than 0.32 V for greater than 1 s.

P2128

The ECM detects that the APP sensor 2 voltage is greater than 2.6 V for greater than 1 s.

P2138

The ECM detects that APP sensor 1 and APP sensor 2 disagree greater than 10 percent for greater than 1 s.

OR

The ECM detects that both APP sensor 1 and APP sensor 2 are 5 percent greater than the learned minimum position for greater than 1 s.

  1. DTCs P2122, P2123, P2127, P2128, and P2138 are type A DTCs.
  2. The ECM commands the TAC system to operate in a Reduced Engine Power mode.

DTCs P2122, P2123, P2127, P2128, and P2138 are type A DTCs.

  1. A high resistance condition on the accelerator pedal position circuits could cause a DTC to set.
  2. Ensure that the in-line harness connector seals are installed correctly. Improper installation could result in water intrusion into the connector and cause a DTC to set.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON.
  2. Verify DTC P0697 or P06A3 is not set. If any of the 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. If none of the DTCs are set
  3. Verify the APP Sensor 1 Circuit Status and APP Sensor 2 Circuit Status displays OK. If Malfunction is displayed Refer to Circuit/System Testing below. If OK is displayed
  4. Verify the scan tool APP Sensor 1 and 2 Agree/Disagree parameter displays Agree while performing the tests listed below: Rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times. Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times. If Disagree Refer to Circuit/System Testing below. If Agree
  5. Verify that DTC P2122, P2123, P2127, P2128, or P2138 is not set. If any of the DTCs are set Refer to Circuit/System Testing below. If none of the DTCs set
  6. 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.
  7. Verify the DTC does not set. If the DTC sets Refer to Circuit/System Testing below. If the DTC does not set
  8. All OK
  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B107 accelerator pedal assembly. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 5 ohms between each low reference circuit terminal listed below and ground. Low reference circuit terminal 4 or A Low reference circuit terminal 5 or D 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
  3. Ignition ON.
  4. Test for 4.8-5.2 V between each 5 V reference circuit terminal listed below and ground. 5 V reference circuit terminal 1 or C 5 V reference circuit terminal 2 or F 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
  5. Verify each APP sensor voltage parameter is less than 0.2 V. If 0.2 V or greater Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON. Test for less than 1 V between the signal circuit terminal listed below and ground. APP sensor 1 signal circuit terminal 3 or E APP sensor 2 signal circuit terminal 6 or B 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 less than 0.2 V
  6. Install a 3 A fused jumper wire between each signal circuit terminal listed below and the 5 V reference circuit terminal 1 or C. APP sensor 1 signal circuit terminal 3 or E APP sensor 2 signal circuit terminal 6 or B
  7. Verify the scan tool APP sensor voltage parameter is greater than 4.8 V. If 4.8 V or less Ignition OFF, disconnect the harness connector at the K20 engine control module. Test for infinite resistance between the signal circuit terminal 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 4.8 V
  8. Test or replace the B107 accelerator pedal assembly.

Perform the Diagnostic Repair Verification after completing the repair.

  1. «Accelerator Pedal with Position Sensor Assembly Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «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
  1. 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.
  2. 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.
  3. «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 Air Fuel Imbalance diagnostic detects a rich or lean cylinder to cylinder air/fuel ratio imbalance. The diagnostic monitors the pre-catalyst heated oxygen sensor (HO2S) signal's frequency and amplitude characteristics by calculating an accumulated voltage over a predetermined sample period. An imbalance is indicated when multiple samples of the accumulated voltage are consistently higher than the desired value.

  1. DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0122, P0123, P0128, P0201-P0204, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0301-P0304, P0411, P0442, P0443, P0455, P0496, P1248, P1249, P124A, P124B, P2101, P2135, P2147, P2148, P2150. P2151, P2153, P2154, P2156, P2157, P2440, P2444 are not set.
  2. The device control is not active.
  3. The intrusive diagnostics are not active.
  4. The engine overspeed protection is not active.
  5. The engine is in closed loop status.
  6. The system voltage is greater than 11 V for greater than 2 s.
  7. The engine coolant temperature (ECT) is warmer than -20°C (-4°F).
  8. The engine speed is between 900-4, 200 RPM.
  9. The mass air flow is between 7-200 g/s.
  10. The AIR pump is not ON.
  11. Engine run time is greater than 30 s.
  12. Fuel level is greater than 10% and no fuel level sensor fault is present.
  13. The DTC runs continuously when the above conditions have been met.

Multiple samples of the pre-catalyst HO2S accumulated voltage are consistently greater than the desired value.

DTC P219A is a Type A DTC.

DTC P219A is a Type A DTC.

  1. The air fuel imbalance diagnostic is very sensitive to heated oxygen sensor (HO2S) design. A non-OE sensor or an incorrect part number may cause a DTC to set.
  2. Monitoring the misfire current counters, or misfire graph, may help to isolate the cylinder that is causing the condition.
  3. Certain aftermarket air filters may cause a DTC to set.
  4. Certain aftermarket air induction systems or modifications to the air induction system may cause a DTC to set.
  5. Certain aftermarket exhaust system components may cause a DTC to set.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Troubleshooting with a Test Lamp»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__troubleshooting-with-a-test-lamp)
  3. «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)
  4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
  5. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

  1. Read and record the Freeze Frame/Failure Records data taking note of the speed and load at which the DTC set.
  2. Diagnose any other DTCs that 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) .
  3. With the engine idling and the transmission in the Park or Neutral position, observe the manifold absolute pressure (MAP) sensor parameter. The MAP sensor parameter should be between 20-48 kPa. If the MAP sensor parameter is not between 20-48 kPa, refer to «DTC P0106»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) .
  4. Inspect the air induction system for modified, damaged, leaking, or restricted components.
  5. Inspect the crankcase ventilation system for improper operation. 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) .
  6. Inspect the vacuum hoses for splits, kinks, and improper connections.
  7. Test for a restricted, damaged, leaking, or modified exhaust system from the catalytic converter forward. Refer to «Symptoms - Engine Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__symptoms-engine-exhaust) .
  8. Test the fuel injectors for improper operation. 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) .
  9. Test for 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) .
  10. Test for excessive fuel in the crankcase due to leaking injectors. Change engine oil as necessary.
  11. Test the ignition system for improper operation. 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) .
  12. Test the engine for any mechanical conditions such as sticking valves, lifters, etc., which could alter the flow into the combustion chamber. Refer to «Symptoms - Engine Mechanical»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verify the repair under the same speed and load as noted in the Freeze Frame/Failure Records data recorded during testing.

  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
5 V ReferenceP0651, P2432P2431P0651, P2431P2430, P2431
Secondary Air Injection Pressure Sensor SignalP2432P2432P2433P2430, P2431
Low ReferenceP2433P2430, P2431
CircuitShort to GroundOpenShort to Voltage
Parameter Normal Range: BARO Operating Conditions: Engine running under various operating conditions
5 V Reference41 kPa (5.9 psi)41 kPa (5.9 psi)111 kPa (16.1 psi)
AIR Pressure Sensor Signal42 kPa (6.1 psi)41 kPa (5.9 psi)150 kPa (21.8 psi)
Low Reference145 kPa (21 psi)

Secondary Air Injection Pressure Sensor

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 secondary air injection pressure sensor is used to monitor the air flow from the secondary air injection pump. The Engine Control Module (ECM) supplies voltage to the 5 V reference circuit and provides a ground for the low reference circuit. The sensor provides a signal voltage to the ECM relative to the pressure changes within the secondary air injection system.

DTC P2430

  1. DTC P0412, P0418, P0606, P0641, P0651, P2432, or P2433 is not set.
  2. Greater than 60 min has elapsed since the last cold start.
  3. The barometric pressure (BARO) is greater than 60 kPa (8.7 psi).
  4. The intake air temperature (IAT) is greater than -11°C (12°F).
  5. The engine coolant temperature (ECT) is between -11 to +60°C (12-140°F).
  6. The ignition voltage is between 10-32 V.
  7. The manifold absolute pressure (MAP) sensor is greater than 20 kPa (2.9 psi).
  8. The engine speed is less than 5, 000 RPM.
  9. The mass air flow (MAF) is less than 50 g/s.
  10. The AIR pump is commanded ON.
  11. DTC P2430 runs continuously when the above conditions are met.

DTC P2431

  1. DTC P0101, P0102, P0103, P0300, P0301, P0302, P0304, P0412, P0418, P0606, P0641, P0651, P2432, or P2433 is not set.
  2. The barometric pressure (BARO) is greater than 60 kPa (8.7 psi).
  3. The intake air temperature (IAT) is greater than -11°C (12°F).
  4. The engine coolant temperature (ECT) is between -11 to +60°C (12-140°F).
  5. The ignition voltage is between 10-32 V.
  6. The manifold absolute pressure (MAP) sensor is greater than 20 kPa (2.9 psi).
  7. Run/Crank is not active.
  8. The engine speed is less than 5, 000 RPM.
  9. The mass air flow (MAF) is less than 50 g/s.
  10. Greater than 60 minutes has elapsed since the last cold start.
  11. DTC P2431 runs continuously when the above conditions are met.

P2432 and P2433

  1. DTC P0606, P0641, or P0651 is not set.
  2. The ignition is ON or the engine is running.
  3. DTC P2432 and P2433 run continuously when the above conditions are met.

P2430

The ECM determines that the pressure sensor value change is less than a calibrated value.

P2431

  1. The ECM determines that the difference between the Secondary Air Injection pressure sensor and the BARO sensor signal is greater than 14 kPa (2.0 psi) or less than -10 kPa (-1.5 psi) when the Secondary Air Injection Pump is commanded OFF. OR
  2. The ECM determines that the difference between the Secondary Air Injection pressure sensor and the BARO sensor signal is greater than 50 kPa (21.8 psi) when the Secondary Air Injection Pump is commanded ON.

DTC P2432

The Secondary Air Pressure sensor signal is less than 0.3 V for greater than 5 s.

DTC P2433

The Secondary Air Pressure sensor signal is greater than 4.7 V for greater than 5 s.

DTCs P2430, P2431, P2432 and P2433 are Type B DTCs.

DTCs P2430, P2431, P2432 and P2433 are Type B DTCs.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0641 or P0651 is 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.
  2. Compare the scan tool BARO pressure 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 should be within the specified range displayed in the table for the specific altitude. 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.
  3. Compare the scan tool Secondary Air Injection Pressure Sensor pressure parameter to the BARO reading. The readings should be within 3 kPa (0.4 psi).
  4. 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.
  1. Ignition OFF, disconnect the harness connector at the Q29 Secondary Air Injection Solenoid Valve.
  2. 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 3 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.
  3. 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.
  4. Verify the scan tool Secondary Air Injection Pressure Sensor voltage parameter is less than 0.5 V. If greater than the specified range, test the signal circuit terminal 2 for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the 5 V reference circuit terminal 1. Verify the scan tool Secondary Air Injection Pressure Sensor voltage parameter is greater than 4.8 V. If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  6. If all circuits test normal, test or replace the Q29 Secondary Air Injection Solenoid Valve.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Secondary Air Injection Check Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for Engine Control Module replacement, setup, and programming
  1. 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.
  2. 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.
  3. «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 engine control module (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 as follows

  1. DTCs P0411 and P2430 run during Phase 1
  2. DTCs P2430 and P2440 run during Phase 2
  3. 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.

  1. 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, P0411, 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.
  2. Greater than 30 min has elapsed since the last cold start.
  3. The ignition voltage is between 10-32 V.
  4. The barometric pressure (BARO) is greater than 60 kPa (8.7 psi).
  5. The engine coolant temperature (ECT) is between -11 to +60°C (12-140°F).
  6. The intake air temperature (IAT) is greater than -11°C (+12°F).
  7. The manifold absolute pressure (MAP) sensor is greater than 20 kPa (2.9 psi).
  8. The mass air flow (MAF) is less than 50 g/s.
  9. The engine speed is less than 5, 000 RPM.
  10. The secondary air injection system is commanded ON.
  11. The DTC runs continuously once the above conditions are met for greater than 3 s.

The ECM detects that the secondary air system pressure is less than a calibrated threshold for greater than 1.5 s.

DTC P2440 is a Type B DTC.

DTC P2440 is a Type B DTC.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON.
  2. Verify that DTC P0411, P0412, P0418, P2430, P2431, P2432, or P2433 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.
  3. 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) table. 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. If within the specified range
  4. Verify the scan tool Secondary Air Injection Pressure Sensor parameter and the BARO pressure parameter are within 3 kPa (0.4 psi). If not within the specified range Replace the Q29 secondary air injection solenoid valve. If within the specified range
  5. Engine running
  6. Command the Secondary Air Injection Pump Relay ON with a scan tool. Verify the scan tool Secondary Air Injection Pressure Sensor parameter increases between 15-22 kPa (2.2-3.2 psi). If not within the specified range Refer to Circuit/System Testing below. If within the specified range
  7. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. If the DTC sets Refer to Circuit/System Testing below. If the DTC does not set
  8. All OK
  1. Ignition OFF, disconnect the KR26 secondary air injection solenoid valve relay. Ignition ON.
  2. Verify a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates Repair the short to voltage on the circuit. If the test lamp does not illuminate
  3. Ignition OFF, connect the KR26 secondary air injection solenoid valve relay.
  4. Disconnect the harness connector at the Q29 secondary air injection solenoid valve. Ignition ON.
  5. Verify a test lamp does not illuminate between the control circuit terminal 5 and ground. If the test lamp illuminates Test or replace the KR26 secondary air injection solenoid valve relay. If the test lamp does not illuminate
  6. Verify the following conditions do not exist: Hoses/pipes restricted or blocked upstream of valve Hoses/pipes leaking or disconnected Damaged or restricted secondary air injection pump Damaged secondary air injection check valve If a condition is located Repair or replace the affected component as necessary. If all components test normal
  7. Ignition OFF, remove the Q29 secondary air injection solenoid valve.
  8. Connect the harness connector at the Q29 secondary air injection solenoid valve.
  9. Connect the secondary air injection pipe to the Q29 secondary air injection solenoid valve.
  10. Ignition ON, command the Secondary Air Injection Pump Relay ON with a scan tool. Verify there is NO airflow through the Q29 secondary air injection solenoid valve. If airflow Replace the Q29 secondary air injection solenoid valve. If no airflow
  11. Replace the G21 secondary air injection pump.

Relay Test

  1. Ignition OFF, disconnect the KR26 secondary air injection solenoid valve relay.
  2. Test for 70-110 ohms between terminals 85-86. If not within the specified range Replace the relay. If within the specified range
  3. 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
  4. Install a 15 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground.
  5. Test for less than 2 ohms between terminals 30 and 87. If 2 ohms or greater Replace the relay. If less than 2 ohms
  6. All OK

Perform the Diagnostic Repair Verification after completing the repair.

  1. «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)
  2. «Secondary Air Injection Check Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  3. «Secondary Air Injection Check Valve Pipe Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  4. «Secondary Air Injection Pipe Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  5. «Secondary Air Injection Pump Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  6. «Secondary Air Injection Pump Inlet Hose Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  7. «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
  1. 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.
  2. 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.
  3. «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 engine control module (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 as follows

  1. DTCs P0411 and P2430 run during Phase 1
  2. DTCs P2430 and P2440 run during Phase 2
  3. 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.

  1. DTC P0101, P0102, P0103, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0128, P0201, P0202, P0203, P0204, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P0280, P0282, P0283, 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, P2227, P2228, P2229, P2230, P2430, P2431, P2432, or P2433 is not set.
  2. Greater than 30 min has elapsed since the last cold start.
  3. The ignition voltage is between 10-32 V.
  4. The barometric pressure (BARO) is greater than 60 kPa (8.7 psi).
  5. The engine coolant temperature (ECT) is between -11 to +56°C (12-133°F).
  6. The intake air temperature (IAT) is greater than -11°C (+12°F).
  7. The manifold absolute pressure (MAP) sensor is greater than 20 kPa (2.9 psi).
  8. The engine speed is less than 5, 000 RPM.
  9. The mass air flow (MAF) is less than 50 g/s.
  10. The AIR system is commanded ON.
  11. Phase 1 and phase 2 of the secondary air injection system test have run and passed.
  12. The DTC runs continuously once the above conditions are met for greater than 4 s.

The ECM detects that the Secondary Air System pressure is greater than expected for greater than 4 s.

DTC P2444 is a Type B DTC.

DTC P2444 is a Type B DTC.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Ignition ON, command the Secondary Air Injection Pump Relay ON and OFF with a scan tool. The Secondary Air Pump should turn ON and OFF.
  2. 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.
  1. Ignition OFF, disconnect the harness connector at the G21 Secondary Air Injection Pump.
  2. Ignition ON, verify that a test lamp does not illuminate between the G21 Secondary Air Injection Pump ignition voltage circuit terminal A and ground. If the test lamp illuminates, test the ignition circuit for a short to voltage.
  3. If the circuit tests normal replace the KR25 Secondary Air Injection Pump Relay.

Perform the Diagnostic Repair Verification after completing the repair.

  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen or High ResistanceShort to VoltageSignal Performance
IGN VoltageP2534P2534

The fuel pump control module monitors the ignition voltage circuit in order to determine if the voltage is within the normal operating range.

The engine is running.

The FPCM detects that the IGN voltage is less than 6.0 V.

DTC P2534 is a Type A DTC.

DTC P2534 is a Type A DTC.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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

  1. Verify that DTC P0562 is not set. If DTC P0562 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) .
  2. Ignition OFF, disconnect the harness connector of the K27 fuel pump control module.
  3. Ignition ON, test for greater than 11 V between the IGN voltage circuit terminal 15 and ground. If less than the specified voltage, test the IGN voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the MAF/CCC fuse is open, test the voltage circuit for a short to ground. If the circuit tests normal, test or replace the Run/Crank relay.
  4. If all circuits test normal, replace the K27 fuel pump control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «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)
  2. «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, setup, and programming
  1. 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.
  2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for a overview of the diagnostic approach.
  3. «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.

To improve shift feel, the transmission control module (TCM) is constantly sending the engine control module (ECM) serial data messages with information regarding it's request for modifying engine speed or torque. The serial data messages are sent through two circuits which are part of a communication network called the controller area network (CAN). The ECM sets DTC P2544 when it detects a discrepancy in the structure of the message causing the integrity of the message to be questioned.

An intermittent fault in the CAN circuits will cause the ECM to set DTC P2544.

  1. The engine run time is greater than 0.5 s.
  2. No other CAN errors are present.

The ECM detects that the engine speed and torque modification messages from the TCM are either corrupted or intermittently missing for greater than 4 s.

  1. DTC P2544 is a Type B DTC.
  2. The TCM commands maximum line pressure during shifts, which results in harsh shifts.
  3. The TCM freezes adaptive functions.

DTC P2544 is a Type B DTC.

DTC Type Reference

Note. DTC P2544 is an informational DTC. Diagnose all other engine control module DTCs prior to DTC P2544.

  1. Verify there are no other engine control module or communication DTCs 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) If a DTC is not set
  2. Complete the diagnosis by looking for an intermittent CAN circuit fault. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#data-communications-system) . If an intermittent CAN circuit fault is found Repair as necessary. If an intermittent CAN circuit fault is not found
  3. All OK.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for TCM replacement, setup, and programming.

  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
ControlP0231P023FP0232P023F, P2635
Low ReferenceP023FP023F, 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 closes the ground switch of the fuel pump and also supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel pressure.

  1. DTC P018B, P018C, P018D, P0231, P0232, P023F, P064A, P1255 or P06A6 are not active.
  2. DTC P0641 has not failed this ignition cycle.
  3. Fuel pump control is enabled and the fuel pump control state is normal.
  4. The system voltage is greater than 11 V.
  5. The engine has been running for more than 30 seconds.

This DTC sets when the fuel pump control module detects a predetermined fuel pressure performance degradation between the desired fuel pressure and the current fuel pressure.

DTC P2635 is a Type B DTC.

DTC P2635 is a Type B DTC.

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.

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

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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. Do not replace the fuel pump control module based on a history DTC P2635. The DTC P2635 may be stored but that does not indicate a failure of the fuel pump control module. Refer to Strategy Based Diagnosis for further history DTC diagnostics.

  1. Verify that DTCs P018C, P018D, P0231, P0232, or P023F are not 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) .
  2. Ignition OFF, disconnect the harness connector at the G12 fuel pump.
  3. Ignition OFF, test for less than 5.0 ohms between the G12 fuel pump low reference circuit terminal 2 and ground. If greater than the specified range, test the G12 fuel pump low reference circuit for a high resistance. If the circuit tests normal, replace the K27 fuel pump control module.
  4. Ignition OFF, install a test lamp between the control circuit terminal 1 and the low reference circuit terminal 2.
  5. 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 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.
  6. Perform the «Fuel System Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-36l-dtc-p0341-to-dtc-p2635-and-diagnostic-information-and-procedures) to verify proper fuel pressure. If the fuel pressure is not normal, replace the G12 fuel pump
  7. If all circuits test normal, replace the K27 fuel pump control module.

Perform the Diagnostic Repair Verification after completing the repair.

  1. «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)
  2. «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
  1. 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.
  2. 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.
  3. «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.

Symptoms Description

Symptoms covers conditions that are not covered by DTCs. Certain conditions can cause multiple symptoms. These conditions are listed together under Symptoms Testing. Conditions that may only cause specific symptoms are listed separately under Additional Symptoms Testing. Perform the Symptoms Testing before using the Additional Symptoms Testing.

Symptoms Verification

Before using the Symptom tables, perform the following inspections

  1. Verify that the malfunction indicator lamp (MIL) is operating correctly. Use the scan tool to command the lamp ON and OFF.
  2. Verify that there are no DTCs that are stored.
  3. Verify that the scan tool data is within a normal operating range. Refer to «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for scan tool information.
  4. Verify the customer concern.
  5. Perform the Visual/Physical Inspection in this section. The visual/physical inspection is extremely important, and can lead to correcting a condition without additional testing. It may also help reveal the cause of an intermittent condition.

Identifying Intermittent Conditions

Many intermittent conditions occur with harness or connector movement due to engine torque, rough pavement, vibration or physical movements of a component. Refer to the following for a list of issues that may cause an intermittent condition

  1. Moisture and water intrusion in connectors, terminals, and components
  2. Incomplete connector mating
  3. Poor terminal contact
  4. High circuit or component resistance-High resistance can include any resistance, regardless of the amount, which can interrupt the operation of the component.
  5. Harness that is too short or tight
  6. Wire insulation that is chaffed or cut
  7. High or low ambient temperature
  8. High or low engine coolant temperatures
  9. High underhood temperatures
  10. Heat build up in component or circuit due to circuit resistance, poor terminal contact, or high electrical load
  11. High or low system voltage
  12. High vehicle load conditions
  13. Rough road surfaces
  14. Electro-magnetic interference (EMI)/circuit interference from relays, solenoids or other electrical surge
  15. Incorrect installation of aftermarket, add on accessories

Visual/Physical Check

  1. Verify that the control module grounds are clean, tight, and correctly located.
  2. Verify that the vacuum hoses are not split or kinked, and are properly connected, as shown on the Vehicle Emission Control Information label.
  3. Verify that the air filter is clean and free from restrictions.
  4. Verify that there is no water intrusion in connectors terminals and components.
  5. Inspect the air intake ducts for the following conditions: Collapsed Damaged areas Looseness Incorrect installation Leaking
  6. Inspect for air leaks at the throttle body mounting area, the mass air flow (MAF) sensor and intake manifold sealing surfaces.
  7. Inspect the wiring harness for the following conditions: Poor connections Pinches Cuts
  8. Inspect for loose, damaged, unseated, or missing sensors/components.
  9. Inspect the terminals for corrosion and correct contact.

Symptoms Testing

Backfire, Cuts Out/Misses, Detonation/Spark Knock, Dieseling/Run-On, Engine Control Module (ECM) Commanded Reduced Engine Power, Hard Start, Hesitation/Sag/Stumble, Lack of Power/Sluggishness/Sponginess, Poor Fuel Economy, Rough, Unstable, or Incorrect Idle and Stalling, or Surges/Chuggles

  1. Test the fuel system for the following: Correct operation and 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) . Improperly operating 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) . Improper fuel quality condition-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) .
  2. Test the ignition system for the following: Spark plugs with incorrect heat range or an abnormal condition-Refer to «Spark Plug Inspection»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__spark-plug-inspection) , and «Ignition System Specifications»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-specifications__ignition-system-specifications) . Coolant or oil fouled spark plugs-For diagnosis, refer to «Coolant in Combustion Chamber»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__coolant-in-combustion-chamber) , or «Oil Consumption Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__oil-consumption-diagnosis) . Secondary ignition system susceptible to moisture. Engine running, wet down the secondary ignition system with water from a spray bottle to help locate damaged or deteriorated components. Look/listen for arcing or misfiring as the water is applied. Weak spark using the J 26792 spark tester -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) .
  3. Inspect for the following conditions: Improper operation of the transmission torque converter clutch (TCC) - The scan tool should indicate an engine speed drop when the TCC is commanded ON. For Non-Hybrid equipped vehicles, refer to «Torque Converter Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/automatic-trans/#automatic-transmission-6t40-diagnostic-information-and-procedures) . Improper operation of the A/C compressor An engine that runs lean or rich-Observe the Fuel Trim parameters with a scan tool. Refer to «DTC P0171 or P0172»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) . Slow responding heated oxygen sensors (HO2S). The heated oxygen sensors should respond quickly to different throttle positions. Refer to appropriate procedures for additional information. CAUTION: Refer to «Heated Oxygen and Oxygen Sensor Caution»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#dangers-warnings-and-cautions__heated-oxygen-and-oxygen-sensor-caution) . Water intrusion in the heated oxygen sensors connector NOTE: The embossed arrows on the mass air flow (MAF) sensor indicate the direction of the intake air flow. The arrows must point toward the engine. Improper MAF sensor installation. A mass air flow sensor that is improperly installed may cause a hard start. Install the mass air flow in the proper direction. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) . Improper mass air flow (MAF) sensor connections. Engine oil contaminated by fuel Split or kinked vacuum hoses-Verify that the routing and connections are as shown on the Vehicle Emission Control Information label. Excessive knock sensor system spark retard activity-Observe the Knock Retard parameter on the scan tool for activity more than 0°.
  4. Electromagnetic interference (EMI) on the reference circuit, which can cause a misfire condition. You can usually detect electromagnetic interference with a scan tool by monitoring the engine speed parameter. A sudden increase in the engine speed parameter with little change in actual engine speed indicates that electromagnetic interference is present. Inspect the high voltage components near the ignition control circuit if a condition exists.
  5. A crankshaft position sensor with an intermittent condition-Observe the scan tool Crankshaft Position Resync Counter parameter. The Resync Counter parameter should remain at 0 during all operating conditions, and when moving the related harnesses and connectors between the crankshaft position sensor and the ECM.
  6. A stuck open evaporative emission (EVAP) canister purge solenoid.
  7. Improper operation of the crankcase ventilation valve-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) .
  8. The exhaust system components for the following: Physical damage or possible internal failure Restricted three-way catalytic converters For more information, refer to «Symptoms - Engine Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__symptoms-engine-exhaust) .
  9. The engine cooling system for the following conditions: A thermostat with incorrect heat range. Refer to «Thermostat Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis) . Improper engine coolant level-If the level is low, refer to «Loss of Coolant»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant) .
  10. Inspect the engine for the following mechanical failures: Refer to «Symptoms - Engine Mechanical»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l) . Excessive oil in the combustion chamber or leaking valve seals Oil Consumption Incorrect cylinder compression Sticking or leaking valves Worn camshaft lobes Incorrect valve timing Worn rocker arms Broken valve springs Excessive carbon buildup in the combustion chambers-Clean the chambers with top engine cleaner. Follow the instructions on the can. Incorrect engine parts
  11. If the above conditions do not address the symptom, refer to the additional symptoms tests.

Additional Symptoms Tests

Detonation/Spark Knock

  1. Verify that the engine coolant temperature (ECT) has not shifted in value. Allow the engine to run and reach operating temperature. Observe the ECT Sensor parameter with a scan tool and compare the reading to that parameter listed on the «Engine Control Module Scan Tool Information (LFX or LFW)»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-specifications-scan-tool-information-1-of-2__engine-control-module-scan-tool-information) , «Engine Control Module Scan Tool Information (LUK)»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-specifications-scan-tool-information-2-of-2__engine-control-module-scan-tool-information) , list. If the reading is not in the range specified in the list, test the resistance of the engine coolant temperature sensor. 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) , for resistance specifications. Replace the engine coolant temperature sensor if the resistance is not within specification. Refer to «Engine Coolant Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) . If the sensor is within the specification, test the engine coolant temperature sensor circuits for high resistance.
  2. Test for an engine overheating condition. Refer to «Engine Overheating»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating) .
  3. Inspect for excessive carbon buildup in the combustion chambers. Clean the chambers with Top Engine Cleaner, if necessary. Follow the instructions on the can.
  4. If there are no engine mechanical faults, fill the fuel tank with a known high quality fuel that meets the vehicle minimum octane requirements.

Engine Control Module (ECM) Commanded Reduced Engine Power

Under certain conditions the engine control module may limit engine power by reducing engine torque and, for some vehicles, fuel pressure as well. For most, but not all of the conditions, the engine control module will illuminate the reduced engine power lamp on the instrument panel cluster, however a DTC may not be set. Observe the scan tool Reduced Engine Power History parameter, if applicable, or refer to Engine Control Module Scan Tool Information (LFX or LFW) , Engine Control Module Scan Tool Information (LUK) to determine the reason for the reduced engine power event.

Verify or inspect for the following

  1. Vehicle being operated at sustained high engine speeds, or, towing heavy loads up an incline for an extended period of time, which may cause the engine oil or coolant to overheat. A repair may not be necessary. Inspect the airflow passageways in front of the engine for obstructions and clear away any debris or foreign material that is found. If no obstructions are found, review approved driving habits with the customer. The customer may need to operate the vehicle at a higher engine speed to improve cooling system performance, or, at a slower engine speed to reduce engine load.
  2. A cooling fan condition which may cause the engine control module to reduce engine power. Refer to «Cooling Fan Description and Operation»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__cooling-fan-description-and-operation) , and «Cooling System Description and Operation»(/buick/lacrosse/ii-2009-2013/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-description-and-operation) to verify correct operation of the cooling fan.
  3. Temporarily reduced engine power. Under extremely cold ambient temperatures some SIDI equipped vehicles may experience engine control module commanded reduced engine power for a few minutes during engine warm-up. This would be a normal condition, noticeable only at wide open throttle, and the reduced engine power lamp would not be illuminated.
  4. If the vehicle is equipped with the OnStar® feature, reduced engine power may be due to OnStar® remote command. Verify the vehicle is not in the OnStar® initiated Stolen Vehicle Slowdown mode. Refer to «OnStar Stolen Vehicle Slowdown Active»(/buick/lacrosse/ii-2009-2013/remont/door-locks-anti-theft-systems/#immobilizer-system) , and «Remote Vehicle Speed Limiting Description and Operation»(/buick/lacrosse/ii-2009-2013/remont/door-locks-anti-theft-systems/#immobilizer-system__remote-vehicle-speed-limiting-description-and) for additional information.
  5. Excessively high fuel pressure condition. 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) , and «Fuel System Description»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-description-and-operation) to verify fuel system operation.
  6. Maximum recommended engine oil life exceeded. Refer to the Owners Manual for scheduled maintenance recommendations.
  7. Intake air temperature out of range too high. Engine running, observe the scan tool IAT Sensor parameter. The readings should be between -40°C and +149°C (-40°F and +300°F). Refer to «DTC P0112, P0113, or P0114»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) for additional information.
  8. Fuel temperature out of range too high.

Fuel Odor

  1. Inspect for leaking, damaged, or deteriorated fuel lines.
  2. Inspect for a saturated EVAP canister-Refer to «Evaporative Emission Control System Description»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-description-and-operation) .
  3. Inspect for a condition with the internal components of the fuel tank assembly-Refer to «Fuel System Description»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-description-and-operation) .

Hard Start

  1. Observe the scan tool Throttle Body Idle Airflow Compensation parameter. A value greater than 80% may indicate an excessive accumulation of deposits in the throttle bore. Inspect the throttle body and bore and clean, if necessary. Refer to «Throttle Body Cleaning»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__throttle-body-cleaning) .
  2. Test the engine coolant temperature (ECT) sensor. Compare the scan tool ECT Sensor value to the intake air temperature (IAT) sensor value on a cold engine. The ECT and IAT Sensor values should be within 3°C (5°F). If the engine coolant temperature sensor is out of range with the intake air temperature sensor, test the resistance of the engine coolant temperature sensor. 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) , for resistance specifications. Replace the engine coolant temperature sensor if the resistance is not within specification. Refer to «Engine Coolant Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) . If the sensor is within the specifications, test the engine coolant temperature sensor circuits for high resistance.
  3. Verify that the fuel system has adequate pressure for engine start-up. The fuel pump control module should command the fuel pump ON for 2 S when the ignition is turned to ON. Refer to «Fuel System Description»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-description-and-operation) , and «Fuel System Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) for correct fuel pressure specifications.
  4. Inspect for excessive crankshaft endplay that will cause the crankshaft position sensor reluctor wheel to move out of alignment with the crankshaft position sensor. Refer to «Crankshaft and Bearing Cleaning and Inspection»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__crankshaft-and-bearing-cleaning-and-inspection) .

Hesitation, Sag, Stumble

  1. Test the 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) .
  2. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) .
  3. Test the generator. Refer to «Symptoms - Engine Electrical»(/buick/lacrosse/ii-2009-2013/remont/charging-system/#battery-charging-system-and-starting-system-except-hybrid__symptoms-engine-electrical) . Repair the charging system if the generator output voltage is less than 9 V or more than 16 V.
  4. Test the manifold absolute pressure (MAP) sensor. Refer to «DTC P0106»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) .
  5. Inspect for excessive crankshaft endplay that will cause the crankshaft position sensor reluctor wheel to move out of alignment with the crankshaft position sensor. Refer to «Crankshaft and Bearing Cleaning and Inspection»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__crankshaft-and-bearing-cleaning-and-inspection) .
  6. Engine warm and idling, verify the correct operation of the camshaft actuator system. Command the intake and exhaust camshaft actuators from 0 degrees to 25 degrees and back to zero while observing the scan tool Intake Camshaft Position Variance and Exhaust Camshaft Position Variance parameters. Each parameter should be less than 2 degrees in each of the commanded states. If any of the parameters is greater than 2 degrees, inspect the suspect camshaft actuator and camshaft actuator solenoid valve and valve bore for contamination, obstruction, and damage. Refer to «Camshaft Actuator System Description»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-description-and-operation) ,, «Camshaft Position Exhaust Actuator Replacement»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__camshaft-position-exhaust-actuator-replacement) ,, and «Camshaft Position Intake Actuator Replacement»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__camshaft-position-intake-actuator-replacement) .

Lack of Power, Sluggishness, or Sponginess

  1. Inspect the engine electrical system for correct operation. Refer to «Symptoms - Engine Electrical»(/buick/lacrosse/ii-2009-2013/remont/charging-system/#battery-charging-system-and-starting-system-except-hybrid__symptoms-engine-electrical) .
  2. Verify that each injector harness is connected to the correct injector.
  3. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) .
  4. Engine warm and idling, verify the correct operation of the camshaft actuator system. Command the intake and exhaust camshaft actuators from 0 degrees to 25 degrees and back to zero while observing the scan tool Intake Camshaft Position Variance and Exhaust Camshaft Position Variance parameters. Each parameter should be less than 2 degrees in each of the commanded states. If any of the parameters is greater than 2 degrees, inspect the suspect camshaft actuator and camshaft actuator solenoid valve and valve bore for contamination, obstruction, and damage. Refer to «Camshaft Actuator System Description»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-description-and-operation) ,, «Camshaft Position Exhaust Actuator Replacement»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__camshaft-position-exhaust-actuator-replacement) ,, and «Camshaft Position Intake Actuator Replacement»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__camshaft-position-intake-actuator-replacement) .

Poor Fuel Economy

  1. Inspect for heavy loads being carried or towed
  2. Inspect for acceleration rate too much or too often
  3. Inspect for incorrect operation of the speedometer.
  4. Observe the scan tool Throttle Body Idle Airflow Compensation parameter. A value greater than 80% may indicate an excessive accumulation of deposits in the throttle bore. Inspect the throttle body and bore and clean, if necessary. Refer to «Throttle Body Cleaning»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__throttle-body-cleaning) .
  5. Verify that the engine coolant temperature (ECT) has not shifted in value. Allow the engine to run and reach operating temperature. Observe the ECT Sensor parameter with a scan tool and compare the reading to that parameter listed on the «Engine Control Module Scan Tool Information (LFX or LFW)»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-specifications-scan-tool-information-1-of-2__engine-control-module-scan-tool-information) , «Engine Control Module Scan Tool Information (LUK)»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-specifications-scan-tool-information-2-of-2__engine-control-module-scan-tool-information) , list. If the reading is not in the range specified in the list, test the resistance of the engine coolant temperature sensor. 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) , for resistance specifications. Replace the engine coolant temperature sensor if the resistance is not within specification. Refer to «Engine Coolant Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) . If the sensor is within the specification, test the engine coolant temperature sensor circuits for high resistance.
  6. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) .
  7. Inspect the brake system for brake drag.

Rough, Unstable, or Incorrect Idle and Stalling

  1. Observe the scan tool Throttle Body Idle Airflow Compensation parameter. A value greater than 80% may indicate an excessive accumulation of deposits in the throttle bore. Inspect the throttle body and bore and clean, if necessary. Refer to «Throttle Body Cleaning»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__throttle-body-cleaning) .
  2. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) .
  3. Inspect the engine mounts. Refer to «Engine Mount Inspection»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l__engine-mount-inspection) .
  4. Inspect the intake and exhaust manifolds for casting flash.

Surges/Chuggles

  1. Verify that each injector harness is connected to the correct injector.
  2. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions) .
  3. Inspect for slow responding heated oxygen sensors (HO2S). The heated oxygen sensors should respond quickly to a change in throttle position. If the heated oxygen sensors do not respond to different throttle positions, inspect for contamination from fuel, silicon, or the incorrect use of RTV sealant. The sensors may have a white powdery coating and result in a high, but false, signal voltage, which gives a rich exhaust indication. The engine control module reduces the amount of fuel delivered to the engine, causing a drivability condition. Refer to the application system/procedures for additional information.
  1. 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.
  2. 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.
  3. «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 malfunction indicator lamp (MIL) illuminates to inform the driver that an emission system fault has occurred and the engine control system requires service. Ignition voltage is supplied directly to the MIL and, when the emission fault occurs, the engine control module (ECM) turns the MIL ON by grounding the MIL control circuit. Under normal operating conditions, the MIL should be ON only when the ignition is ON and the engine is OFF.

If the condition is intermittent, move the related harnesses and connectors with the ignition ON and the engine OFF, and with the engine operating while monitoring the scan tool MIL control circuit status parameters. The MIL control circuit status parameters will change from OK or Not Run to Malfunction if there is a condition with the circuit or a connection.

Schematic Reference

  1. «Engine Controls Schematics (LUK)»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-wiring-schematic-diagrams)
  2. «Instrument Cluster Schematics»(/buick/lacrosse/ii-2009-2013/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Note. Any MIL requesting DTCs that may be set should be diagnosed first.

  1. Ignition ON, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF as commanded.
  2. Command the MIL ON and OFF with a scan tool while observing the following control circuit status parameters: The MIL Control Circuit Low Voltage Test Status The MIL Control Circuit Open Test Status The MIL Control Circuit High Voltage Test Status Each parameter should display OK or Not Run.
  3. Engine running, command the MIL ON and OFF with a scan tool while observing the following control circuit status parameters: The MIL Control Circuit Low Voltage Test Status The MIL Control Circuit Open Test Status The MIL Control Circuit High Voltage Test Status Each parameter should display OK or Not Run.
  1. Ignition OFF, disconnect the X1 harness connector at the K20 engine control module.
  2. Ignition ON, the malfunction indicator lamp should not illuminate. If the malfunction indicator lamp is illuminated, test the malfunction indicator lamp control circuit terminal 46 X1 for a short to ground. If the circuit tests normal, replace the P16 instrument cluster.
  3. Connect a 3 A fused jumper wire between the malfunction indicator lamp control circuit terminal 46 X1 and ground. The malfunction indicator lamp should illuminate. If the malfunction indicator lamp illuminates, replace the K20 engine control module. If the malfunction indicator lamp does not illuminate, test the malfunction indicator lamp control circuit terminal 46 X1 for a short to voltage or an open/high resistance. If the malfunction indicator lamp control circuit tests normal, test the instrument cluster ignition voltage circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the P16 instrument panel cluster/bulb.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Instrument Cluster Replacement»(/buick/lacrosse/ii-2009-2013/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)
  2. «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for replacement, setup, and programming.
  1. 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.
  2. 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.
  3. «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.

This Engine Cranks but Does Not Run diagnostic is an organized approach to identify a condition which causes the engine to crank but not start. This diagnostic directs the technician to the appropriate system diagnosis.

Inspect for any of the following conditions

  1. When attempting to start the engine, the mechanical portion of the vehicle key must be locked in the fully extended position with the fob parallel to the key. Leaving the key partially retracted or folded over when starting may interrupt transponder authentication and result in an intermittent no-start condition. In such instances, DTC B3055 may also be set. If an intermittent no-start complaint is received, it may be necessary to discuss with the customer their starting habits and verify they are locking the key in the fully extended position, fob parallel to the key, before starting.
  2. The engine control module (ECM) uses the camshaft position sensors to determine engine speed and position when there is a crankshaft position sensor condition.
  3. The engine will operate with a crankshaft position sensor condition only if the ECM has stored the learned reference position of the camshafts in memory. With a crankshaft position sensor condition in the signal circuit, the engine will go into a limp home mode after a hard restart. The ECM then calculates engine speed from one of the camshaft position sensors.
  4. The fuel pump flow control module controls and monitors the operation of the in-tank fuel pump. If the fuel pump flow control module detects a fault, a DTC sets in the fuel pump flow control module. The fuel pump flow control module will then send a serial data message to the engine control module (ECM) requesting the illumination of the malfunction indicator lamp (MIL).
  5. Insufficient fuel can cause a no start condition. Thoroughly inspect the fuel delivery system for sufficient fuel volume to the fuel injectors. Inspect the fuel supply components for partial blockage or restrictions.
  6. The fuel injectors are calibrated to begin operating when the fuel rail pressure reaches 0.7 Mpa (101.5 psi) at 20-32°C (68-90°F). This specification will vary when the temperature is outside of this range.
  7. Fuel injectors with partially blocked and restricted nozzles, or a malfunctioning solenoid, can cause a no start 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) .
  8. There may be fuel spray at the fuel injectors and the indicated fuel pressure may be correct, yet there may not be enough fuel to start the engine. If the fuel injectors and the injector circuit are OK, and fuel spray is detected, the fuel injector ON time may be inadequate. If the engine control module (ECM) receives incorrect inputs from the various information sensors, the fuel delivered by the fuel injectors may be inadequate to start the engine. Check all the engine data parameters with a scan tool and compare the values indicated with the expected values or the values from a known good vehicle.
  9. Inspect the engine for good secure electrical grounds.
  10. Water or foreign material in the fuel can cause a no start or engine will not stay running condition. During freezing weather water can freeze inside the fuel system. The engine may start after 30 min in a heated repair shop. The malfunction may not recur until parked overnight in freezing temperatures. Extreme weather conditions can cause contaminated fuel to prevent the vehicle from starting.
  11. A vehicle that starts and runs after being brought to the repair shop for a no start condition, may have an ignition system that is susceptible to moisture. Spray water on the ignition system components and the wiring in order to check for an engine starting or will not stay running concern.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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 26792 HEI Spark Tester

CH-48027 Digital Pressure Gauge

Note. This diagnostic assumes the following: The battery is completely charged. The engine cranking speed is acceptable. There is adequate fuel in the fuel tank.

  1. Engine cranking, observe the DTC information with a scan tool. Verify that DTC P0116, P0117, P0335, P0336, P0513, P0601-P0604, P0606, P062B, P0627-P0629, P0633, P069E, P1631, P1649, or U0109 does not set. If any of the listed 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) .
  2. Ignition ON, observe the Security Indicator on the instrument cluster. The security indicator should illuminate momentarily. If the security indicator stays ON or is flashing, review the scan tool DTC information for Immobilizer system DTCs-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 more information concerning the Immobilizer system, refer to «Immobilizer Description and Operation»(/buick/lacrosse/ii-2009-2013/remont/door-locks-anti-theft-systems/#immobilizer-system__immobilizer-description-and-operation) .
  3. Engine cranking, observe the scan tool Engine Speed parameter. The parameter value should indicate an engine speed greater than 0 RPM. If the engine speed is 0 RPM, 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.
  4. Engine cranking, observe the scan tool Mass Airflow Sensor parameter. The parameter should display greater than 0 Hz. If the parameter is not the specified value, refer to «DTC P0102 or P0103»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0010-to-dtc-p0418) for further diagnosis.
  5. Test the ignition system for 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) .
  6. Ignition OFF, all accessories OFF, install a CH-48027 digital pressure gauge -Refer to «Fuel Pressure Gauge Installation and Removal»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__fuel-pressure-gauge-installation-and-removal) .
  7. Ignition ON, engine OFF, command the Fuel Pump Enable ON with a scan tool. Verify the fuel pressure is between 345-690 kPa (50-100 psi) while the fuel pump is running. If the fuel pump runs but the pressure is not the specified value, 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) . If the fuel pump does not run, refer to «Fuel Pump Electrical Circuit Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
  8. Verify the fuel pressure after the pump is turned OFF, decreases to 500-599 kPa (72-87 psi) and does not decrease greater than 34 kPa (5 psi) in 1 minute from that point. If not the specified value, 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) .
  9. Verify that the following conditions do not exist: Collapsed air intake duct to the throttle body Restricted air filter element Gas or coolant fouled spark plugs A skewed engine coolant temperature (ECT) sensor-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) . Restricted exhaust system-Refer to «Restricted Exhaust»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system__restricted-exhaust) . 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) . An engine mechanical condition, for example, worn timing chain and gears, low compression-Refer to «Symptoms - Engine Mechanical»(/buick/lacrosse/ii-2009-2013/remont/mechanical/#engine-mechanical-24l) . If you find any of the above conditions, repair as necessary.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. 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.
  2. 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.
  3. «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.
CircuitShort to GroundOpen or High ResistanceShort to VoltageSignal Performance
Fuel Pump High SignalP0231P023FP0232P023F, P2635
Fuel Pump Low SignalP023FP023F, 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 two seconds, unless the engine is in crank or run. While this voltage is being received, the fuel pump control module closes the ground switch of the fuel pump and also supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel pressure.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «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 output control. The fuel pump should turn on and off.

  1. Ignition OFF, disconnect the harness connector at the G12 fuel pump.
  2. Connect a test lamp between the control circuit terminal 1 and ground.
  3. Ignition ON, command the G12 fuel pump ON and OFF using a scan tool ECM fuel pump output control. 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.
  4. Ignition OFF, connect a test lamp between the control circuit terminal 1 and the low reference circuit terminal 2.
  5. Ignition ON, command the G12 fuel pump ON using a scan tool. The test lamp should illuminate. If the test lamp does not illuminate, test the low reference circuit terminal 1 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K27 fuel pump control module.
  6. If all circuits test normal, replace the G12 fuel pump.

Perform the Diagnostic Repair Verification after completing the repair.

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

  1. 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.
  2. 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.
  3. «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) 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 s, unless the engine is in Crank or Run. While this voltage is being received, the fuel pump control module closes the ground switch of the fuel tank fuel pump module and also supplies a varying voltage to the fuel tank fuel pump module in order to maintain the desired fuel line pressure.

The fuel system is an electronic returnless on-demand design. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.

An electric turbine style fuel pump attaches to the primary fuel pump module inside the fuel tank. The fuel pump supplies fuel through the fuel feed pipe to the high pressure fuel pump. The high pressure fuel pump supplies fuel to a variable-pressure fuel rail. Fuel enters the combustion chamber through precision multi-hole fuel injectors. The high pressure fuel pump, fuel rail pressure, fuel injection timing, and injection duration are controlled by the engine control module (ECM).

The primary fuel tank module also contains a primary jet pump and a secondary jet pump. Fuel pump flow loss, caused by vapor expulsion in the pump inlet chamber, is diverted to the primary jet pump and the secondary jet pump through a restrictive orifice located on the pump cover. The primary jet pump fills the reservoir of the primary fuel tank module. The secondary jet pump creates a venturi action which causes the fuel to be drawn from the secondary side of the fuel tank, through the fuel transfer pipe, to the primary side of the fuel tank.

The fuel injectors are calibrated to begin operating at 0.7 Mpa (101.5 psi) at 20-32°C (68-90°F). This specification will vary when the temperature is outside of this range.

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

  1. CH-48027 Digital Pressure Gauge
  2. J 37287 Fuel Line Shut-Off Adapter

Note. Repair all fuel system related DTCs before performing this diagnostic. Inspect the fuel system for damage or external leaks before proceeding. Verify that adequate fuel is in the fuel tank before proceeding. The Fuel Pump Enable may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. Before proceeding with this test, review the User Manual CH 48027-5 for Safety Information and Instructions.

  1. Ignition OFF, all accessories OFF, install a CH-48027 Gauge.
  2. Ignition ON, engine OFF, command the Fuel Pump Enable ON with a scan tool. Verify the fuel pressure is between 345-690 kPa (50-100 psi) with the fuel pump running.
  3. Engine idling at normal operating temperature, the Fuel Pump Flow Control Module Fuel Pressure Sensor parameter should read between 300-400 kPa (43-58 psi).
  1. Ignition ON, engine OFF, command the Fuel Pump Enable ON with a scan tool and observe the fuel pressure gauge while the fuel pump is operating. Verify the fuel pressure is between 345-690 kPa (50-100 psi). If the fuel pressure is greater than the specified range, replace the fuel tank fuel pump module. If the fuel pressure is less than the specified range, test, inspect, and repair the items listed below. If all items test normal, replace the fuel tank fuel pump module. Restricted fuel feed pipe Inspect the harness connectors and the ground circuits of the fuel tank fuel pump module for poor connections.
  2. Verify that the fuel pressure, after the fuel pump is turned off, decreases to 500-599 kPa (72-87 psi), and does not decrease more than 34 kPa (5 psi) in 1 minute from that point. If the fuel pressure stays above 600 kPa (87 psi), replace the fuel tank fuel pump module. If the fuel pressure decreases more than the specified value, perform the following procedure: Ignition OFF, relieve the fuel pressure. Refer to «Fuel Pressure Relief»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions__fuel-pressure-relief) . Disconnect the chassis fuel feed hose from the engine compartment fuel pipe. Install the J 37287 Adapter between the chassis fuel hose and the engine compartment fuel pipe. Open the valve on the J 37287 Adapter. Ignition ON, command the Fuel Pump Enable ON with a scan tool and bleed the air from the CH-48027 Gauge. Command the Fuel Pump Enable ON and then OFF with a scan tool. Close the valve on the J 37287 Adapter. Monitor the fuel pressure for 1 min. If the fuel pressure decreases more than 34 kPa (5 psi) within the specified time, locate and replace the leaking fuel injector(s). If the fuel pressure does not decrease more than 34 kPa (5 psi) within the specified time, replace the fuel tank fuel pump module.
  3. Relieve the fuel pressure to 69 kPa (10 psi). Verify that the fuel pressure does not decrease greater than 14 kPa (2 psi) in 5 min. If the fuel pressure decreases greater than the specified value, replace the fuel tank fuel pump module.
  4. Operate the vehicle within the conditions of the customer's concern while monitoring the fuel pressure with the CH-48027 Gauge. The fuel pressure should not drop off during acceleration, cruise, or hard cornering. If the fuel pressure drops off, test, inspect, and repair the items listed below. If all items test normal, replace the fuel tank fuel pump module. Restricted fuel feed pipe Inspect the harness connectors and the ground circuits of the fuel tank fuel pump module for poor connections.
  5. If the fuel system tests normal, refer to «Symptoms - Engine Controls»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) ,, «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) ,, and «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.

  1. «Direct Fuel Injector Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  2. «Fuel Feed Pipe Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  3. «Fuel Pump Fuel Feed Hose Replacement»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-repair-instructions)
  4. «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)
  1. 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.
  2. 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.
  3. «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) supplies a separate high voltage supply circuit and a high voltage control circuit for each fuel injector. The injector high voltage supply circuit and the high voltage control circuit are both controlled by the ECM. The ECM energizes each fuel injector by grounding the control circuit. The ECM controls each fuel injector with 65 V. This is controlled by a boost capacitor in the ECM. During the 65 V boost phase, the capacitor is discharged through the injector high voltage supply circuit, allowing for initial injector opening. The injector is then held open with 12 V. A fuel injector coil winding resistance that is too high or too low will affect the engine driveability. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

Schematic Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Note. The resistance test must be performed at the fuel injector or mis-diagnosis will occur. The DMM and test leads must be calibrated to 0 ohms in order to prevent mis-diagnosis.

  1. Remove the intake manifold and disconnect the appropriate Q17 fuel injector.
  2. Test for 1.9-2.3 ohms at 20°C (68°F) between the high voltage supply circuit terminal 2 and the high voltage control circuit terminal 1 at the fuel injector. If not within the specified range, replace the Q17 fuel injector.
  3. Measure the resistance between each terminal at the Q17 fuel injector and the Q17 fuel injector housing/case. The DMM should display OL ohms. If less than the specified value, replace the Q17 fuel injector.
  4. If the injectors measure OK, perform the Fuel Injector Balance Test. 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) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. 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.
  2. 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.
  3. «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 injector balance test is performed while the engine is running at idle. The scan tool pressurizes the fuel rail to a predetermined pressure before each injector is pulsed for a precise amount of time allowing a measured amount of the fuel to be injected. This causes a drop in the system fuel pressure that is recorded and used to compare each injector.

  1. Monitoring the Current Misfire Counters may help to isolate the fuel injector that is causing the condition.
  2. Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.

Note. DO NOT perform this test if the engine coolant temperature (ECT) is above 60°C (140°F). Irregular fuel pressure readings may result due to hot soak fuel boiling. Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.

Fuel Injector Balance Test

  1. Verify the correct low side 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) .
  2. Engine idling at normal operating temperature, observe the Fuel Rail Pressure Sensor parameter with a scan tool. The pressure should be approximately 3 MPa (435 psi).
  3. Engine running at normal operating temperature. With a scan tool, select the Fuel Injector Balance function within the Output Controls menu.
  4. Select and test an injector. Repeat for each injector in order to obtain a pressure drop value for each injector.
  5. After all injectors are tested, record the fuel pressure drops.
  6. Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
  7. Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop.
  8. Multiply the average pressure drop by 0.20. This is the acceptable variance from the average pressure drop, 20 percent. If the difference between any individual pressure drop and the average pressure drop is more than the acceptable variance, replace the fuel injector.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. 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.
  2. 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.
  3. «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.

Test Description

Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no start, or misfires in one or more cylinders. Water may collect near a single fuel injector at the lowest point in the fuel injection system and cause a misfire in that cylinder. If the fuel system is contaminated with water, inspect the fuel system components for rust or deterioration.

Ethanol concentrations of greater than 10 percent can cause driveability conditions and fuel system deterioration. Fuel with more than 10 percent ethanol could result in driveability conditions such as hesitation, lack of power, stalling, or no start. Excessive concentrations of ethanol used in vehicles not designed for it may cause fuel system corrosion, deterioration of rubber components, and fuel filter restriction.

Special Tool

CH 44175-A Fuel Composition Tester

For equivalent regional tools, refer to the appropriate regional tool supplier/catalogue.

System Verification

The fuel sample should be drawn from the bottom of the tank so that any water present in the tank will be detected. The sample should be bright and clear.

  1. If the sample appears cloudy, or contaminated with water, as indicated by a water layer at the bottom of the sample, perform the Particulate Contaminants in Fuel Testing Procedure.
  2. If alcohol contamination is suspected, perform the Alcohol in Fuel Testing procedure.

Alcohol in Fuel Testing with Special Tool

  1. Test the fuel composition using the CH 44175-A Fuel Composition Tester and the Instruction Manual.
  2. If water appears in the fuel sample, clean the fuel system.
  3. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample.
  4. If the fuel sample contains more than 15 percent ethanol, add fresh, regular gasoline to the vehicle's fuel tank.
  5. Test the fuel composition.
  6. If testing shows the ethanol percentage is still more than 15 percent, replace the fuel in the vehicle.

Alcohol in Fuel Testing without Special Tool

  1. Using a 100 ml (3.38 oz.) specified cylinder with 1 ml (0.034 oz.) graduation marks, fill the cylinder with fuel to the 90 ml (3.04 oz.) mark.
  2. Add 10 ml (0.34 oz.) of water in order to bring the total fluid volume to 100 ml (3.38 oz.) and install a stopper.
  3. Shake the cylinder vigorously for 10-15 seconds.
  4. Carefully loosen the stopper in order to release the pressure.
  5. Re-install the stopper and shake the cylinder vigorously again for 10-15 seconds.
  6. Put the cylinder on a level surface for approximately 5 minutes in order to allow adequate liquid separation. If alcohol is present in the fuel, the volume of the lower layer, which would now contain both alcohol and water, will be more than 10 ml (0.34 oz.). For example, if the volume of the lower layer is increased to 15 ml (0.51 oz.), this indicates at least 5 percent alcohol in the fuel. The actual amount of alcohol may be somewhat more because this procedure does not extract all of the alcohol from the fuel.

Particulate Contaminants in Fuel Testing Procedure

  1. Using an approved fuel container, draw approximately 0.5 liter (0.53 qt) of fuel.
  2. Place the container on a level surface for approximately 5 minutes in order to allow settling of the particulate contamination. Particulate contamination will show up in various shapes and colors. Sand will typically be identified by a white or light brown crystals. Rubber will appear as black and irregular particles.
  3. Observe the fuel sample. If any physical contaminants or water are present, clean the fuel system.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. 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.
  2. 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.
  3. «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.

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 circuit of each ignition coil/module to enable a spark event.

  1. Depending on location in the spliced ignition voltage circuit, a slight resistance can cause a misfire or a crank/no start concern. A voltage drop test will pinpoint this condition.
  2. A slight to moderate resistance on any ignition control circuit can cause a misfire before DTC P0351-P0354 sets.
  3. Extended engine cranking time, may foul the spark plugs with excessive fuel.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «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)
  4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 26792 HEI Spark Tester

  1. Ignition OFF, disconnect the harness connector at the affected T8 ignition coil/modules.
  2. Ignition OFF, all vehicle systems OFF. This may take up to 2 minutes. Test for less than 5 ohms between the ground circuit terminal A/1 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Test for less than 5 ohms between the low reference circuit terminal B/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.
  4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal D/4 and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  5. Exchange the affected T8 ignition coil/module with the T8 ignition coil/module of a good cylinder.
  6. Start the engine, and observe the scan tool Misfire Current Cylinder parameters. If the misfire transfers with the suspect T8 ignition coil/module, replace as needed.
  7. If the circuits test normal, test or replace the spark plug/s.

Use the J 26792 Spark Tester to verify the output of each ignition coil/module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

Evaporative Emission System Diagnosis

Special Tools

EN 41413-VLV EVAP Service Port Vent Fitting

Operating Instructions for the Evaporative Emission System Tester (EEST)

Vehicle Setup

  1. Engine OFF, open the hood. Position a large fan to blow air under the vehicle onto the fuel tank area.
  2. Connect the red battery clip from the tester to the positive battery terminal.
  3. Connect the black battery clip from the tester to chassis ground.

Flow Meter Test - Leak Detection

  1. Open the Nitrogen tank valve and turn the NITROGEN/SMOKE valve on the front control panel to NITROGEN.
  2. Connect the hose to the correct test orifice on the bottom front of the tester. For orifice size, refer to the vehicle specific information found in service procedures for DTCs that relate to evaporative emission (EVAP) system leaks.
  3. Press and release the remote switch to activate the tester.
  4. Position the sliding red flag on the flow meter to align with the floating indicator. When the red flag is set, press and release the remote switch to deactivate the tester.
  5. Remove the hose from the test orifice and install the hose onto the vehicle. For proper connection location, and the special tool numbers for any adapters that may be required, refer to the service procedures for DTCs that relate to EVAP system leaks.
  6. Ignition ON, seal the EVAP system per instructions in the service procedures for DTCs that relate to EVAP system leaks. Most systems can be sealed using a scan tool output control for the EVAP vent solenoid valve, other systems require that the vent system be plugged.
  7. Press and release the remote switch to activate the nitrogen flow and fill the system.
  8. Compare the stable floating indicator position to the red flag. Below the red flag, the result is acceptable, Pass. Test complete Above the red flag, the result is unacceptable, Fail. Go to the Smoke Procedure below.
  9. Press and release the remote switch to deactivate the tester.

Smoke Procedure - Locate the Leak

  1. Turn OFF any fans that may cause air movement around or near the vehicle.
  2. Connect the nitrogen/smoke hose to the vehicle as directed in the service procedures. Some vehicles require that the nitrogen/smoke hose be connected at the front of the EVAP system at the EVAP service port. An adapter may be necessary. Other vehicles require the connection be made at the rear of the system using an adapter at the fuel fill cap. Consult the service procedures for DTCs that relate to evaporative emission (EVAP) system leaks for vehicle specific instructions regarding connection location and adapters.
  3. Open the nitrogen tank valve and turn the nitrogen/smoke valve on the control panel to smoke.
  4. Press and release the remote switch to activate the tester and inject smoke into the EVAP system.
  5. Verify smoke has filled the EVAP system by opening the system opposite the end where smoke is injected. When injecting smoke at the service port, remove the fuel fill cap until smoke is observed. Then close the system and continue testing. If using a special tool fuel fill cap adapter at the filler neck, vent the system at the service port, with special tool EN 41413-VLV EVAP Service Port Vent Fitting, until smoke is observed then remove the vent fitting tool and close the system to continue with the test.
  6. Press and release the remote switch to deactivate the tester.
  7. Introduce smoke into the system for an additional 60 s. Continue introducing smoke at 15 s intervals, as necessary.
  8. Using a high-intensity white light, inspect the entire EVAP system path, and look for the source of the leak indicated by the exiting smoke. Introduce smoke at 15 s intervals, as needed, until leak source is identified.

Temperature Variation Instructions

The Concern

Ideal circumstances for conducting the EVAP flow meter test require equal temperatures between the nitrogen gas and the vehicle EVAP system. Significant differences in temperature between them can result in a flow or pressure change during testing, causing misleading results. Typically, the EEST is stored indoors, approximately 21°C (70°F). Vehicles brought in for diagnosis may have an EVAP system at significantly different temperatures.

For Example

Note. With no temperature difference between the nitrogen gas and EVAP system, the resulting vehicle EVAP system pressure will remain stable at 3.2 kPa, 13 in. H2O (0.5 PSI) once pressurized, providing no leaks are present.

When the EVAP flow meter tests are performed with significant differences in temperature between the nitrogen gas and the vehicle EVAP system, the following results can occur

  1. An increase in flow during the flow meter test can be caused by a vehicle's warm EVAP system cooling down.
  2. A decrease in flow during the flow meter test can be caused by a vehicle's cool EVAP system warming up.

The Solution

When working on a vehicle with significant temperature differences between the vehicle EVAP system and the nitrogen gas, allow the vehicle EVAP system temperature to stabilize as close as possible to the temperature of the nitrogen gas before conducting the Flow Meter Test.

  1. 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.
  2. 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.
  3. «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.

Description

Several states require that a vehicle pass on-board diagnostic (OBD) system tests and the inspection/maintenance (I/M) emission inspection in order to renew license plates. This is accomplished by viewing the I/M System Status display on a scan tool. Using a scan tool, the technician can observe the I/M System Status in order to verify that the vehicle meets the criteria that complies with the local area requirements. While testing in the I/M System Status mode, some DTCs may occur that are called I/M Test DTCs. An I/M Test DTC is defined as a fault code that is currently commanding the MIL ON, and is stored in non-volatile memory. The intended use of this data is to prevent vehicles from passing I/M inspection without proper repair to the vehicle. These fault codes are not erasable from any scan tool command or erasable by disconnecting power to the controller. The I/M Test DTCs will be supported by all emissions related ECUs such as ECMs, TCMs, FPCMs, etc. An I/M Test DTC will not be stored or erased from the ECU except at the end of trip processing which occurs 5 s after ignition OFF.

Conditions for Updating the I/M System Status

Each system requires at least one, and sometimes several, diagnostic tests. The results of these tests are reported by a diagnostic trouble code (DTC). A system monitor is complete when either all of the DTCs comprising the monitor have Run and Passed, or any one of the DTCs comprising the monitor have illuminated the malfunction indicator lamp (MIL). Once all of the tests are completed, the I/M System Status display will indicate YES in the Completed column.

For example, when the HO2S Heater Monitor indicates YES, either all of the oxygen sensor heater tests have passed or one of the tests has illuminated the MIL. If the vehicle has four heated oxygen sensors, either all four heater circuit tests have passed or one of the heater circuit tests has illuminated the MIL. The I/M System Status will indicate NO under the Completed column when any of the required tests for that system have not run. The following is a list of conditions that would set the I/M System Status indicator to NO

  1. The vehicle is new from the factory and has not yet been driven through the necessary drive conditions to complete the tests.
  2. The battery has been disconnected or discharged below operating voltage.
  3. The control module power or ground has been interrupted.
  4. The control module has been reprogrammed.
  5. The control module DTCs have been cleared as part of a service procedure.

Conditions for Clearing I/M Test DTCs

  1. Only the OBD II System can erase the I/M Test DTC. The OBD II system must determine that the malfunction that caused the I/M Test DTC to be stored is no longer present and is not commanding the MIL. Each of the following represents ways to clear an I/M Test DTC: If the MIL goes out due to 3 passing drive cycles, scan tool code clear is not used, the I/M Test DTC is erased at power down of the last drive cycle. If a scan tool code clear is used to turn OFF the MIL, the I/M Test DTC is not erased, the DTC must PASS and not FAIL. The I/M Test DTC is erased at power down of the drive cycle. If the controller is reflashed/reprogrammed, all I/M Test DTCs are erased.
  2. For the OBD II System to run a single drive cycle for clearing an I/M Test DTC, all of the following conditions must occur: Cumulative time of engine run time is greater than 600 s. Cumulative vehicle operation above 40 km/h (25 mph) for over 300 s. Continuous vehicle idle for greater than 30 s. Turn ignition OFF for 5 s and allow the code to clear.

Monitored Emission Control Systems

The OBD II system monitors all emission control systems that are on-board. Not all vehicles need every possible emission control system. For example, a vehicle may not be equipped with secondary air injection (AIR) or exhaust gas recirculation (EGR). The OBD II regulations require monitoring of the following; if equipped

  1. The air conditioning system
  2. The catalytic converter efficiency
  3. Comprehensive component monitoring-Emission related inputs and outputs
  4. The evaporative emission (EVAP) system
  5. The fuel delivery system
  6. Heated catalyst monitoring
  7. Misfire monitoring
  8. The oxygen sensor system (O2S or HO2S)
  9. The oxygen sensor heater system (HO2S heater)

For the specific DTCs required for each system, refer to Inspection/Maintenance (I/M) System DTC Table . Systems such as misfire and comprehensive components may not be listed in a system status list. These tests run continuously and do not require an I/M System Status indicator.

The I/M System Status display provides an indication of when the control module has completed the required tests. This does not necessarily mean that the test has passed, only that a decision was made. If the diagnostic fails, a DTC will indicate the failure. If a failure indication is present for a DTC associated with one of the I/M regulated systems, it may prevent other required tests from running. For example, a DTC for the control circuit of the EVAP purge solenoid may not be listed in the Inspection/Maintenance System DTC Table because it is a continuous test. If this DTC is set, the Active Tests for the EVAP system may not run.

The I/M System Status information may be useful for a technician to determine if diagnostics have run when verifying repairs.

Review the I/M System Status indicators. All I/M System Status indicators should report YES, and no I/M Test DTCs should be present.

  1. Observe the Engine DTC information with a scan tool. Verify no DTCs are present. If a DTC is set that would prevent the I/M System Status tests from completing, diagnose that DTC before continuing. 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) .
  2. Review applicable service bulletins for software updates that would prevent the I/M System Status tests from completing. If a control module re-program or other repair is required, perform the «Inspection/Maintenance Complete System Set Procedure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
  3. Observe the I/M System Status indicators. If any I/M System Status indicators report NO, perform the «Inspection/Maintenance Complete System Set Procedure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
  4. Observe the I/M Test DTC information with a scan tool. Verify there are no I/M Test DTCs present. If an I/M Test DTC is set and all of the I/M System Status indicators are Yes, there is no need to perform the Complete System Set Procedure. Diagnose the DTC using 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 refer to Conditions for Clearing the I/M Test DTCs. If an I/M Test DTC is set and the I/M System Status indicators are NO, diagnosis the DTC and perform the «Inspection/Maintenance Complete System Set Procedure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
  1. 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.
  2. 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.
  3. «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 purpose of the Inspection/Maintenance Complete System Set Procedure is to satisfy the enable criteria necessary to execute all of the I/M readiness diagnostics and complete the drive cycles for those particular diagnostics. When all I/M monitored diagnostic tests are completed, the I/M System Status indicators are set to YES. Perform the Inspection/Maintenance Complete System Set Procedure if any I/M System Status indicators are set to NO.

Inspection/Maintenance Data List

To determine if the inspection/maintenance readiness diagnostic tests can be run this ignition cycle, use a scan tool to observe the inspection/maintenance monitor enabled parameters in the inspection/maintenance Data List.

Conditions for Meeting a Cold Start

  1. The ignition voltage between 11-18 V.
  2. The barometric pressure is more than 75 kPa (10.9 psi).
  3. The start-up engine coolant temperature is between 4-30°C (39-86°F).
  4. The start-up intake air temperature is between 4-30°C (39-86°F).
  5. The difference between the IAT and the ECT is less than or equal to 6°C (43°F).
  6. The ambient air temperature is between 4-30°C (39-86°F).
  7. The fuel level is between 15-85 %.

Review the inspection/maintenance system status indicators with a scan tool. All I/M system status indicators should report YES, and no I/M Test DTCs should be present.

Inspection/Maintenance System Set Procedure

  1. Ensure that the vehicle meets the conditions for a cold start listed above.
  2. The evaporative emission inspection/maintenance system status indicator should display YES. If the inspection/maintenance system status indicator displays NO, perform the Service Bay Test, if applicable. If the Service Bay Test is NOT available, it may take up to 6 drive cycles, with up to 17 h between drive cycles, for the inspection/maintenance system status indicator to transition to YES.
  3. The O2S Heater inspection/maintenance system status indicator should display YES. If the O2S Heater inspection/maintenance system status indicator displays NO, ensure that the ignition has been turned OFF for at least 10 h.
  4. Turn OFF all accessories; HVAC system, other electrical loads, including aftermarket/add-on equipment, etc.
  5. Set the vehicle parking brake and ensure the vehicle is in Park for automatic transmission or Neutral for manual transmission.
  6. Turn OFF all accessories; HVAC system, other electrical loads, including aftermarket/add-on equipment, etc.
  7. Start and idle the engine for at least 2 min and until 65°C (149°F) is achieved.
  8. Run the engine for 6.5 min within the following conditions: MAF parameter between 4-30 g/s Engine speed steady between 1, 000-3, 000 RPM
  9. Return the engine to idle for 1 minute.
  10. Apply and hold the brake pedal, and shift to Drive for automatic transmission, or apply the clutch pedal for manual transmission and operate the vehicle within the following conditions for 2 min: Depress the accelerator pedal until throttle position sensor angle is more than 2 %. Mass air flow signal between 15-30 g/s RPM steady between 1, 200-2, 000 RPM
  11. Release the accelerator pedal and shift the vehicle to Park for automatic transmission, or Neutral and release the clutch pedal for manual transmission, and allow the engine to idle for 2 min.
  12. Quickly depress the accelerator pedal until throttle position sensor angle is more than 8 % and return to idle, repeat 3 times.
  13. Allow engine to idle for at least 2 min.
  14. Release the parking brake and drive vehicle at 24 km/h (15 mph) or slower for 2 min.
  15. Continue to drive the vehicle for at least 5.5 mi between 45-112 km/h (28-70 mph) with the vehicle reaching at least 80 km/h (50 mph).
  16. Release the accelerator pedal for at least 2 s. This will allow the vehicle to enter decel fuel cut-off.
  17. Depress the accelerator pedal until the throttle position sensor angle is increased 3-20 % and maintain a safe speed for 1 min.
  18. Safely stop the vehicle, with the engine in Drive for automatic transmission or in Neutral with the clutch pedal depressed and parking brake applied for manual transmission, idle for 2 min.
  19. Shift to Park for automatic and apply the parking brake, or neutral and release clutch pedal for manual.
  20. Turn OFF the ignition and exit the vehicle. Do NOT disturb the vehicle for 60 min.
  21. Observe the Inspection/Maintenance System Status with a scan tool. All of the Inspection/Maintenance System Status indicators should display YES. If the evaporative emission Inspection/Maintenance System Status indicator displays NO, turn OFF the ignition for 17 h, ensure that the vehicle meets the conditions for a cold start, and repeat steps 12-18 six more times, or until the evaporative emission Inspection/Maintenance System Status indicator transitions to YES. If the indicator continues to display NO, refer to the «Inspection/Maintenance (I/M) System DTC Table»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures__inspectionmaintenance-im-system-dtc-table) to identify the DTCs that did not run. Follow the Conditions for Running the DTC in order to set the evaporative emission Inspection/Maintenance System Status indicator If any of the Inspection/Maintenance System Status display NO, refer to the «Inspection/Maintenance (I/M) System DTC Table»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures__inspectionmaintenance-im-system-dtc-table) for the indicator which did not display YES. The Inspection/Maintenance System DTC Table identifies the DTCs associated with each Inspection/Maintenance System Status Indicator. Follow the Conditions for Running the DTC in order to set the associated status indicator.
  22. Observe the I/M Test DTC information with a scan tool. Verify there are no I/M Test DTCs present. If an I/M Test DTC is set, diagnose the DTC using 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 refer to «Inspection/Maintenance System Check»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) for clearing I/M Test DTCs. If an I/M Test DTC is set and the I/M System Status indicators are NO, diagnosis the DTC and perform the «Inspection/Maintenance Complete System Set Procedure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) .
  23. Observe the engine DTC information with a scan tool. Verify no DTCs are present. If a DTC is set, diagnose using 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) . After repairs, perform the «Inspection/Maintenance Complete System Set Procedure»(/buick/lacrosse/ii-2009-2013/remont/testing-diagnostics/#engine-controlsfuel-24l-dtc-p0420-to-dtc-p2635-and-diagnostic-information-and-procedures) to verify no further DTCs are set.

Inspection/Maintenance (I/M) System DTC Table

SystemDTCs Required to Set System Status to YES
If an I/M System Status indicator did NOT update to YES during the Inspection/Maintenance Complete System Set Procedure , review each indicator and reference this table to determine each DTC associated with the I/M System Status Indicator. Each DTC listed below has specific conditions that must be met for the diagnostic to run. Included within the conditions are additional DTCs, which if set, may inhibit the DTCs listed below from running. Reviewing and operating the vehicle within the Conditions for Running for each DTC listed below will allow the I/M System Status Indicators to transition to YES.
CatalystDTC P0420
EVAPDTC P0442 DTC P0446 DTC P0451-P0454 DTC P0455 DTC P0496
Oxygen SensorDTC P0030, P0036, P0053, P0054, P0135, or P0141
Oxygen Sensor HeaterDTC P0030, P0036, P0053, P0054, P0135, or P0141
Camshaft SystemDTC P0011 or P0014

Inspection/Maintenance (I/M) System DTC Table

Poor Fuel Fill Quality

ProblemCauses
DEFINITION: During the fueling process a continual, occasional, or no-fuel nozzle shut-off condition has occurred.
Difficult to fillFuel fill limiter vent valve stuck closed Evaporative emission (EVAP) canister restricted EVAP vent valve stuck closed Hose between canister and canister vent solenoid twisted or kinked if applicable High fuel temperature Fuel filler hose is kinked Faulty dispensing nozzle Ignition switch ON, vent valve closed
Over fillFill limiter vent valve stuck open or leaking Fuel inlet check valve stuck open
Pre-mature shut-off of the fuel dispensing nozzle occurs immediately after engaging dispensing nozzle, tank emptyRestricted vapor lines or fuel fill pipe High fuel temperature Inlet check valve at tank stuck closed, fill pipe full of fuel Fuel tank full, gauge not accurate
Pre-mature shut-off of the fuel dispensing nozzle, more than 1/8 of tank capacity dispensedKinked, pinched or plugged lines in fuel tank vent system EVAP vent valve stuck closed or restricted EVAP canister restricted Fuel limiting vent valve stuck closed or obstruction at top of fuel tank
Fuel SpitbackRestricted EVAP canister High fuel temperature Ignition switch ON, EVAP vent valve closed

Poor Fuel Fill Quality

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Control Module References
• Diagnostic Trouble Code (DTC) List - Vehicle
• Exhaust Leakage
• Restricted Exhaust
• Heated Oxygen Sensor Replacement - Sensor 2
• Catalytic Converter Replacement (LUK)
• Engine Controls Schematics (LUK)
• COMPONENT CONNECTOR END VIEWS - INDEX
• Evaporative Emission Control System Description
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Diagnostic Repair Verification
• Throttle Body Cleaning
• Crankcase Ventilation System Inspection/Diagnosis (Without Turbocharger)
• Battery Inspection/Test
• Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement
• Fuel Pressure Sensor Replacement - Fuel Feed Pipe
• Instrument Cluster Schematics
• Power Distribution Schematics
• Electrical Center Identification Views
• Relay Replacement (Within an Electrical Center)
• Relay Replacement (Attached to Wire Harness)
• Hybrid Modes of Operation Description
• DTC P0231, P0232, or P023F
• Electronic Ignition System Description
• Engine Control Module Description
• Engine Control Module Scan Tool Information (LFX or LFW)
• Engine Control Module Scan Tool Information (LUK)
• Fuel Pump Replacement
• Symptoms - Engine Exhaust
• Road Test Warning
• Troubleshooting with a Test Lamp
• DTC P0106
• Symptoms - Engine Mechanical
• Secondary Air Injection System Description
• Altitude Versus Barometric Pressure
• Scan Tool Does Not Communicate with High Speed GMLAN Device
• Fuel System Diagnosis
• Fuel Tank Fuel Pump Module Replacement (NT7)
• Spark Plug Inspection
• Ignition System Specifications
• Coolant in Combustion Chamber
• Oil Consumption Diagnosis
• Torque Converter Diagnosis
• Heated Oxygen and Oxygen Sensor Caution
• Thermostat Diagnosis
• Loss of Coolant
• Temperature Versus Resistance (Engine Coolant Temperature Sensor)
• Engine Overheating
• Cooling Fan Description and Operation
• Cooling System Description and Operation
• OnStar Stolen Vehicle Slowdown Active
• Remote Vehicle Speed Limiting Description and Operation
• Crankshaft and Bearing Cleaning and Inspection
• Symptoms - Engine Electrical
• Camshaft Position Exhaust Actuator Replacement
• Camshaft Position Intake Actuator Replacement
• Engine Mount Inspection
• Immobilizer Description and Operation
• Fuel Pressure Gauge Installation and Removal
• Fuel Pressure Relief
• Fuel System Cleaning
• Fuel and Evaporative Emission Pipe Warning
• Clean, Dry, Low Pressure Gas Source Caution
• Fuel and Evaporative Emission Hose/Pipe Connection Cleaning Caution
• Evaporative Emission System Diagnosis
• Fuel System Diagnosis
• Inspection/Maintenance (I/M) System DTC Table

More articles — Engine Performance