Engine Control System - 3.6l (ly7) - DTC p0008 to DTC p0133 Buick LaCrosse I

Description

The engine control module (ECM) tests for a mis-alignment between both camshafts on one bank of the engine and the crankshaft. The mis-alignment would be at an idler sprocket for bank 1 or at the crankshaft. Once the ECM learns the position of both camshafts on one bank of the engine, the ECM compares the learned values to a reference value. If the ECM detects both learned values for one bank of the engine is exceeding a calibrated threshold in the same direction, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P0008 Engine Position System Performance Bank 1

Conditions for Running the DTC

1. DTCs P0010, P0011, P0013, P0014, P0020, P0021, P0023, P0024, P0341, P0342, P0343, P0346, P0347, P0348, P0366, P0367, P0368, P0391, P0392, P0393, P2088, P2089, P2090, P2091, P2092, P2093, P2094 and P2095 are not set.
2. The engine is operating.
3. The ECM has learned the camshaft positions.
4. DTC P0008 run continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects that both camshafts on bank 1 of the engine are misaligned with the crankshaft for more than 4 seconds.

Action Taken When the DTC Sets

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

1. Inspect the engine for any recent engine mechanical repairs. An incorrectly installed secondary timing chain can cause this DTC to set.
2. A single failed camshaft actuator or actuator solenoid will not cause this DTC to set. This diagnostic algorithm is designed to detect an alignment condition between a primary intermediate sprocket and the secondary timing chain or the alignment between a primary intermediate sprocket and the crankshaft. Either condition would cause the camshaft timing for both cams on one bank to be off an equal number of degrees.
3. The presence of DTCs P0008 and P0009 along with P0016, P0017, P0018 and P0019 indicate a possible condition with the primary timing chain and the alignment between both intermediate sprockets and the crankshaft or the crankshaft reluctor wheel has moved and is no longer referenced to top dead center (TDC).
4. Observing the desired and actual camshaft angle parameters, with a scan tool before a DTC sets, may help to isolate whether a condition is specific to one camshaft, one bank or caused by a condition with the primary crankshaft timing.
5. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 5: Inspect the crankshaft for a crankshaft position (CKP) reluctor wheel that has moved in its relationship to top dead center (TDC) on the crankshaft gear.

DTC P0008

The engine control module (ECM) tests for a mis-alignment between both camshafts on one bank of the engine and the crankshaft. The mis-alignment would be at an idler sprocket for bank 2 or at the crankshaft. Once the ECM learns the position of both camshafts on one bank of the engine, the ECM compares the learned values to a reference value. If the ECM detects both learned values for one bank of the engine is exceeding a calibrated threshold in the same direction, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0009 Engine Position System Performance Bank 2

1. DTCs P0010, P0011, P0013, P0014, P0020, P0021, P0023, P0024, P0341, P0342, P0343, P0346, P0347, P0348, P0366, P0367, P0368, P0391, P0392, P0393, P2088, P2089, P2090, P2091, P2092, P2093, P2094 and P2095 are not set.
2. The engine is operating.
3. The ECM has learned the camshaft positions.
4. DTC P0009 run continuously once the above conditions are met.

The ECM detects that both camshafts on bank 2 of the engine are misaligned with the crankshaft for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Inspect the engine for any recent engine mechanical repairs. An incorrectly installed secondary timing chain can cause this DTC to set.
2. A single failed camshaft actuator or actuator solenoid will not cause this DTC to set. This diagnostic algorithm is designed to detect an alignment condition between a primary intermediate sprocket and the secondary timing chain or the alignment between a primary intermediate sprocket and the crankshaft. Either condition would cause the camshaft timing for both cams on one bank to be off an equal number of degrees.
3. The presence of DTCs P0008 and P0009 along with P0016, P0017, P0018 and P0019 indicate a possible condition with the primary timing chain and the alignment between both intermediate sprockets and the crankshaft or the crankshaft reluctor wheel has moved and is no longer referenced to top dead center (TDC).
4. Observing the desired and actual camshaft angle parameters, with a scan tool before a DTC sets, may help to isolate whether a condition is specific to one camshaft, one bank or caused by a condition with the primary crankshaft timing.
5. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 5: Inspect the crankshaft for a crankshaft position (CKP) reluctor wheel that has moved in its relationship to top dead center (TDC) on the crankshaft gear.

DTC P0009

Circuit Description

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

Ignition voltage is supplied directly to the CMP actuator solenoid. The 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.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC P0010 Intake Camshaft Position (CMP) Actuator Solenoid Control Circuit Bank 1
2. DTC P0013 Exhaust Camshaft Position (CMP) Actuator Solenoid Control Circuit Bank 1
3. DTC P0020 Intake Camshaft Position (CMP) Actuator Solenoid Control Circuit Bank 2
4. DTC P0023 Exhaust Camshaft Position (CMP) Actuator Solenoid Control Circuit Bank 2

1. The engine speed is more than 80 RPM.
2. The ignition 1 voltage is between 10-18 volts.
3. The ECM has commanded the CMP actuator solenoid ON and OFF at least once during the ignition cycle.
4. DTCs P0010, P0013, P0020 and P0023 runs continuously once the above conditions are met for more than 1 second.

1. The ECM detects an open in the CMP actuator solenoid circuits when the solenoid is commanded OFF.
2. The condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0010, P0013, P0020 or P0023

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault if there is a condition with the circuit or a connection. The ODM information is in the output driver module (ODM) data list.
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines if the condition exists. The engine speed must be increased to enable the CMP actuator solenoids. The DTC will not set unless the solenoid is commanded ON and OFF at least once during the ignition cycle.
2. 5: This step verifies that the ECM is providing a ground to the CMP actuator solenoid.
3. 7: This step determines if there is an internal condition with the ECM. The CMP actuator control circuit is pulled-up to a voltage within the ECM. The ECM uses this voltage as a feedback circuit. 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 voltage is not within the specified range, there is a condition with the ECM.

DTC P0010, P0013, P0020 or P0023

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

Ignition voltage is supplied directly to the CMP actuator solenoid. The ECM controls the solenoid by grounding the control circuit with a solid state device called a driver. If the ECM detects the desired camshaft position and the actual camshaft position angles are not within a calibrated value, this DTC sets.

This diagnostic procedure supports the following DTCs

1. DTC P0011 Intake Camshaft Position (CMP) System Performance Bank 1
2. DTC P0014 Exhaust Camshaft Position (CMP) System Performance Bank 1
3. DTC P0021 Intake Camshaft Position (CMP) System Performance Bank 2
4. DTC P0024 Exhaust Camshaft Position (CMP) System Performance Bank 2

1. Before the ECM can report DTC P0011, P0014, P0021 or P0024 failed, DTCs P0010, P0013, P0020, P0023, P0341, P0342, P0343, P0346, P0347, P0348, P0366, P0367, P0368, P0391, P0392, P0393, P2088, P2089, P2090, P2091, P2092, P2093, P2094 and P2095 must run and pass.
2. DTCs P0016, P0017, P0018, P0019, P0335, P0336 and P0338 are not set.
3. The engine must accelerate such that the CMP actuator system is commanded from the park position to the phased position. This is considered a cam control cycle. There must be a total of 4 cam control cycles for at least 5 seconds each in the phased position.
4. The engine speed is more than 1,000 RPM.
5. The engine is operating for approximately 5 minutes.
6. DTCs P0011, P0014, P0021 and P0024 run continuously once the above conditions are met for more than 1 second.

1. The ECM detects the difference between the desired camshaft position and the actual CMP angles is more than 5 degrees. OR
2. The ECM detects the difference between the actual camshaft angle and the locked position angle is more than 1 degree.
3. The condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0011, P0014, P0021 or P0024

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. The engine oil condition has a major impact on the camshaft actuator system.
3. A low oil level condition may set this DTC. The engine may require an oil change. Inquire with the customer when the last oil change was performed. You may also monitor the Engine Oil Life parameter with a scan tool. Advise the customer an oil change may be required.
4. Inspect the engine for any recent engine mechanical repairs. An incorrectly installed camshaft, camshaft actuator or timing chain can cause this DTC to set.
5. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines if there is a condition with the CMP actuator system.
2. 6: This step is testing the ignition 1 voltage circuit of the CMP actuator solenoid for high resistance. If the voltage at the test lamp probe is not B+, there is a high resistance condition with the circuit.
3. 7: This step is testing the control circuit of the CMP actuator solenoid for high resistance. If the voltage at the test lamp probe is not less than the specified voltage, there is a high resistance condition with the circuit.
4. 11: This step isolates the condition. If the condition follows the CMP actuator solenoid, there is a condition with the solenoid.

DTC P0011, P0014, P0021 or P0024

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

Ignition voltage is supplied directly to the CMP actuator solenoid. The ECM controls the solenoid by grounding the control circuit with a solid state device called a driver. The ECM compares the CMP or the camshaft angle, to the position of the crankshaft. If the ECM detects a deviation between the camshaft position target and the crankshaft position (CKP), this DTC sets.

This diagnostic procedure supports the following DTCs

1. DTC P0016 Crankshaft Position (CKP) - Intake Camshaft Position (CMP) Correlation Bank 1
2. DTC P0017 Crankshaft Position (CKP) - Exhaust Camshaft Position (CMP) Correlation Bank 1
3. DTC P0018 Crankshaft Position (CKP) - Intake Camshaft Position (CMP) Correlation Bank 2
4. DTC P0019 Crankshaft Position (CKP) - Exhaust Camshaft Position (CMP) Correlation Bank 2

1. Before the ECM can report DTC P0016, P0017, P0018 or P0019 failed, DTCs P0010, P0011, P0013, P0014, P0020, P0021, P0023, P0024, P0335, P0336, P0338, P0341, P0342, P0343, P0346, P0347, P348, P0366, P0367, P0368, P0391, P0392, P0393, P2088, P2089, P2090, P2091, P2092, P2093, P2094 and P2095 must run and pass.
2. The engine is operating for more than 5 seconds.
3. The engine coolant temperature is between 0-92°C (32-198°F).
4. The calculated engine oil temperature is less than 120°C (248°F).
5. DTC P0016, P0017, P0018 and P0019 run continuously once the above conditions are met for approximately 10 minutes.

Condition 1

1. The ECM detects that the actual camshaft angle of a single intake camshaft is more than 20 degrees advanced in relationship to the crankshaft.
2. The ECM detects that the actual camshaft angle of a single exhaust camshaft is more than 25 degrees retarded in relationship to the crankshaft.
3. The camshafts are being commanded to the parked position.

Condition 2

1. The learned angle of an intake camshaft is more than 14.5 degrees advanced in relationship to the crankshaft.
2. The learned angle of an exhaust camshaft is more than 14.5 degrees retarded in relationship to the crankshaft.

Either condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. Inspect the engine for any recent engine mechanical repairs. An incorrectly installed camshaft, camshaft actuator, camshaft sensor, crankshaft sensor or timing chain can cause this DTC to set.
3. An actuator that is in the full advance or retard position can cause this DTC to set.
4. The presence of DTCs P0008 and P0009 along with P0016, P0017, P0018 and P0019 indicates a possible condition with the primary timing chain and the alignment between both intermediate sprockets and the crankshaft or the crankshaft reluctor wheel has moved and is no longer referenced to top dead center (TDC).
5. Observing the desired and actual camshaft angle parameters, with a scan tool before a DTC sets, may help to isolate whether a condition is specific to one camshaft, one bank or caused by a condition with the primary crankshaft timing.
6. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines if there is a condition present.
2. 4: The listed DTCs may cause this DTC to set.
3. 5: Inspect the engine for any recent engine mechanical repairs. An incorrectly installed camshaft or timing chain can cause this DTC to set.

DTC P0016, P0017, P0018 or P0019

The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor (O2S) to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensors rate of heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature, the ECM may modulate the heater control circuit to ground, to maintain a desired temperature.

The ECM controls the heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to voltage. The ECM can determine if the control circuit is open, shorted to ground or shorted to a voltage by monitoring the feedback voltage. If the ECM detects the control circuit voltage is within a predetermined range when the circuit is commanded OFF, this DTC sets.

This diagnostic procedure supports the following DTCs

1. DTC P0030 HO2S Heater Control Circuit Sensor 1
2. DTC P0036 HO2S Heater Control Circuit Sensor 2

1. The ignition 1 voltage is between 10-18 volts.
2. The engine speed is more than 80 RPM.
3. DTC P0030 and P0036 runs continuously once the above conditions are met for less than 1 second.

1. The ECM detects an open in the heater circuits of the HO2S when the heater is commanded OFF.
2. The condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0030 or P0036

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault if there is a condition with the circuit or a connection. The ODM information is in the output driver module (ODM) data list.
3. An open fuse in the HO2S heater circuit may be caused by the heater element in one of the sensors. The condition may not be present until the sensor operates for a period of time. If no fault is present in the heater circuit, monitor the amperage of each heater using the DMM to determine if one of the heater elements is the cause of the open fuse.
4. Inspect the sensor pigtail or the harness for contacting the exhaust system.
5. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 4: The engine must be running for the ECM to operate the control circuit.
2. 5: The heater control circuit is equipped with a feedback circuit internal to the ECM. This feedback circuit allows the ECM to determine if the heater control circuit is open, shorted to ground or shorted to a voltage. If the voltage is not within the specified range, there is a condition with the control circuit.

DTC P0030 or DTC P0036 - HO2S Heater Control Circuit (Open)

The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor (O2S) to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensors rate of heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature, the ECM may modulate the heater control circuit to ground, to maintain a desired temperature.

The ECM controls the heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to voltage. The ECM can determine if the control circuit is open, shorted to ground or shorted to a voltage by monitoring the feedback voltage. If the ECM detects the control circuit voltage is less than a predetermined value when the circuit is commanded OFF, this DTC sets.

This diagnostic procedure supports the following DTCs

1. DTC P0031 HO2S Heater Control Circuit Low Voltage Sensor 1
2. DTC P0037 HO2S Heater Control Circuit Low Voltage Sensor 2

1. The ignition 1 voltage is between 10-18 volts.
2. The engine speed is more than 80 RPM.
3. DTC P0031 and P0037 run continuously once the above conditions are met for less than 1 second.

1. The ECM detects a ground in the heater circuits of the HO2S when the heater is commanded OFF.
2. The condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0031 or P0037

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault if there is a condition with the circuit or a connection. The ODM information is in the output driver module (ODM) data list.
3. An open fuse in the HO2S heater circuit may be caused by the heater element in one of the sensors. The condition may not be present until the sensor operates for a period of time. If no fault is present in the heater circuit, monitor the amperage of each heater using the DMM to determine if one of the heater elements is the cause of the open fuse.
4. Inspect the sensor pigtail or the harness for contacting the exhaust system.
5. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 4: The engine must be running for the ECM to operate the control circuit.
2. 5: The heater control circuit is equipped with a feedback circuit internal to the ECM. This feedback circuit allows the ECM to determine if the heater control circuit is open, shorted to ground or shorted to a voltage. If the voltage is not within the specified range, there is a condition with the control circuit.

DTC P0031 or DTC P0037 - HO2S Heater Control Circuit Low Voltage

The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor (O2S) to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensors rate of heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature, the ECM may modulate the heater control circuit to ground, to maintain a desired temperature.

The ECM controls the heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to voltage. The ECM can determine if the control circuit is open, shorted to ground or shorted to a voltage by monitoring the feedback voltage. If the ECM detects the control circuit voltage is more than a predetermined value when the circuit is commanded ON, this DTC sets.

This diagnostic procedure supports the following DTCs

1. DTC P0032 HO2S Heater Control Circuit High Voltage Sensor 1
2. DTC P0038 HO2S Heater Control Circuit High Voltage Sensor 2

1. The ignition 1 voltage is between 10-18 volts.
2. The engine speed is more than 80 RPM.
3. DTC P0032 and P0038 run continuously once the above conditions are met for less than 1 second.

1. The ECM detects a short to voltage in the heater circuits of the HO2S when the heater is commanded ON.
2. The condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0032 or P0038

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault if there is a condition with the circuit or a connection. The ODM information is in the output driver module (ODM) data list.
3. Inspect the sensor pigtail or the harness for contacting the exhaust system.
4. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 4: The engine must be running for the ECM to operate the control circuit.
2. 6: Inspect the HO2S connector for water intrusion, corrosion and bent or damaged terminals.
3. 7: Inspect the HO2S connector for water intrusion, corrosion and bent or damaged terminals.

DTC P0032 or DTC P0038 - HO2S Heater Control Circuit High Voltage

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio. If there is an internal ECM condition with the integrated circuits for the heated oxygen sensor, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0053 HO2S Internal Heater Resistance Bank 1 Sensor 1

1. Before the ECM can report DTC P0053 failed, DTCs P0030, P0031, P0032, P0101, P0121, P0122, P0123, P0130, P0131, P0132, P0133, P0221, P0222, P0223, P0335, P0336, P0338, P167A, P2243 and P2251 must run and pass.
2. The engine is operating.
3. The ignition 1 voltage is between 10.5-18 volts.
4. DTC P0053 runs continuously once the above conditions are met for 40 seconds.

1. There is an internal ECM condition with the integrated circuits for HO2S 1.
2. The condition exists for more than 4 seconds.

1. The control module stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
4. The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

1. A current DTC Last Test Failed clears when the diagnostic runs and passes.
2. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
3. Clear the DTC with a scan tool.

DTC P0053

The mass air flow (MAF) sensor is located in the air intake duct. The MAF sensor is an airflow meter that measures the amount of air that enters the engine. The MAF sensor uses a hot film that is cooled by air flowing past the sensing film as air enters the engine. The amount of cooling is proportional to the amount of the air flow. As the air flow increases, more current is required in order to maintain the hot film at a constant temperature. The engine control module (ECM) uses the MAF sensor in order to provide the correct fuel delivery for all operating conditions. The MAF sensor uses the following circuits in order to operate

1. An ignition 1 voltage circuit
2. A 5-volt reference circuit
3. A low reference circuit
4. A signal circuit

The ECM monitors the following inputs in order to calculate a predicted MAF sensor value

1. The throttle position (TP)
2. The engine speed

The ECM monitors the MAF sensor signal for being stuck in range, for being too low or for being too high for a given operating condition. If the ECM detects the actual MAF sensor signal is not within a predetermined range of the calculated MAF sensor value, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0101 Mass Air Flow (MAF) Sensor Performance

1. Before the ECM can report DTC P0101 failed, DTCs P0102, P0103, P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336 and P0338 must run and pass.
2. DTC P2176 is not set.
3. The engine is operating.
4. The MAF sensor signal is between 0-243 grams per second.
5. The ignition 1 voltage is more than 10.5 volts.
6. The ECM detects more than 150 revolutions of the camshaft.
7. DTC P0101 runs continuously once the above conditions are met for more than 2 seconds.

1. The ECM detects that the MAF sensor signal is not within a predetermined range of the calculated MAF value.
2. The condition exists for 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0101

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. Any un-metered air that enters the engine may cause this DTC to set.
3. Inspect the throttle plate for sticking or for deposits on the throttle plate or in the throttle bore.
4. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A circuit failure may cause this DTC to set. If DTC P0102 or P0103 are set, diagnose DTC P0102 or P0103 first.
2. 6: This step tests for high resistance in the ignition 1 voltage circuit of the MAF sensor. If the DMM does not display near battery voltage there is high resistance in the circuit.
3. 8: The ECM produces a measurable steady-state amperage that provides the 5-volt reference to the MAF sensor. If the amperage on the 5-volt reference circuit is less than 80 mA, test the 5-volt reference circuit for an open or a high resistance.
4. 9: This step tests for high resistance in the signal circuit of the MAF sensor.
5. 10: This step tests for high resistance in the low reference circuit of the MAF/intake air temperature (IAT) sensor. The MAF sensor and the IAT sensor share the low reference circuit. If there is a condition with the low reference circuit, a MAF and IAT sensor DTC may set. The ECM must be completely powered down to obtain an accurate resistance reading. It may take up to 30 minutes for the ECM to power down after the ignition key is removed. Removal of the ECM fuse or the PCM/ETC fuse, allows the ECM to power down completely.
6. 15: Inspect the MAF/IAT sensor connector for water intrusion, corrosion and bent or damaged terminals.
7. 16: Inspect the ECM connectors for water intrusion, corrosion and bent or damaged terminals.

DTC P0101

The mass air flow (MAF) sensor is located in the air intake duct. The MAF sensor is an airflow meter that measures the amount of air that enters the engine. The MAF sensor uses a hot film that is cooled by air flowing past the sensing film as air enters the engine. The amount of cooling is proportional to the amount of the air flow. As the air flow increases, more current is required in order to maintain the hot film at a constant temperature. The engine control module (ECM) uses the MAF sensor in order to provide the correct fuel delivery for all operating conditions. The MAF sensor uses the following circuits in order to operate

1. An ignition 1 voltage circuit
2. A 5-volt reference circuit
3. A low reference circuit
4. A signal circuit

The ECM monitors the MAF sensor signal for being stuck in range, for being too low or for being too high for a given operating condition. If the ECM detects a MAF sensor signal voltage that is too low, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0102 Mass Air Flow (MAF) Sensor Circuit Low Voltage

1. Before the ECM can report DTC P0102 failed, DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0336 and P0338 must run and pass.
2. The engine is operating.
3. The ignition 1 voltage is more than 7.5 volts.
4. DTC P0102 runs continuously once the above conditions are met for less than 1 second.

1. The ECM detects that the MAF sensor signal is less than -11.7 grams per second.
2. The condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0102

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 4: This step tests the ignition 1 voltage circuit. Repair the open or short to ground in the ignition 1 voltage circuit, if the test lamp does not illuminate.
2. 5: The ECM produces a measurable steady-state amperage that provides the 5-volt reference to the MAF sensor. If the amperage on the 5-volt reference circuit is less than 80 mA, test the 5-volt reference circuit for a short to ground, an open or a high resistance.
3. 6: This step tests the signal circuit of the MAF sensor.

DTC P0102

The mass air flow (MAF) sensor is located in the air intake duct. The MAF sensor is an airflow meter that measures the amount of air that enters the engine. The MAF sensor uses a hot film that is cooled by air flowing past the sensing film as air enters the engine. The amount of cooling is proportional to the amount of the air flow. As the air flow increases, more current is required in order to maintain the hot film at a constant temperature. The engine control module (ECM) uses the MAF sensor in order to provide the correct fuel delivery for all operating conditions. The MAF sensor uses the following circuits in order to operate

1. An ignition 1 voltage circuit
2. A 5-volt reference circuit
3. A low reference circuit
4. A signal circuit

The ECM monitors the following inputs in order to calculate a predicted MAF sensor value

1. The intake air temperature (IAT)
2. The engine coolant temperature (ECT)
3. The throttle position (TP)
4. The engine speed

The ECM monitors the MAF sensor signal for being stuck in range, for being too low or for being too high for a given operating condition. If the ECM detects a MAF sensor signal voltage that is too high, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0103 Mass Air Flow (MAF) Sensor Circuit High Voltage

1. Before the ECM can report DTC P0103 failed, DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0336 and P0338 must run and pass.
2. The engine is operating.
3. The ignition 1 voltage is more than 7.5 volts.
4. DTC P0103 runs continuously once the above conditions are met for less than 1 second.

1. The ECM detects that the MAF sensor signal is more than 294 grams per second.
2. The condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0103

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. Inspect for mis-routed harnesses. Inspect the MAF sensor harness for routing that is too close to the following components: Ignition coils Solenoids Relays Motors
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 4: This step tests the signal circuit of the MAF sensor for a short to voltage.
2. 5: This step tests for high resistance in the low reference circuit of the MAF/IAT sensor. The MAF sensor and the IAT sensor share the low reference circuit. If there is a condition with the low reference circuit, a MAF and IAT sensor DTC may set. The ECM must be completely powered down to obtain an accurate resistance reading. It may take up to 30 minutes for the ECM to power down after the ignition key is removed. Removal of the ECM fuse or the PCM/ETC fuse, allows the ECM to power down completely.
3. 6: This step tests the low reference circuit for a short to voltage. The control module or the sensor may be damaged if the circuit is shorted to battery voltage. Ensure that a short to voltage is repaired before replacing any components.
4. 9: Inspect the MAF/IAT sensor connector for water intrusion, corrosion and bent or damaged terminals.
5. 10: Inspect the ECM connectors for water intrusion, corrosion and bent or damaged terminals.

DTC P0103

The intake air temperature (IAT) sensor is an integral part of the mass air flow (MAF) sensor. The IAT sensor is a variable resistor that measures the temperature of the intake air. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and supplies a ground to the low reference circuit. If the ECM detects a low IAT signal voltage, which is a high temperature indication, this DTC sets.

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

DTC P0112

This diagnostic procedure supports the following DTC

DTC P0112 Intake Air Temperature (IAT) Sensor Circuit Low Voltage

1. The engine run time is more than 3 minutes.
2. The engine is idling for more than 10 seconds.
3. DTC P0112 runs continuously once the above conditions are met.

The ECM detects that the IAT is more than 132°C (270°F) for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0112

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. Use the Temperature vs Resistance table in order to test the IAT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in a driveability condition. If the engine has sat overnight, the intake air temperature and the engine coolant temperature values should display within a few degrees. If the temperatures are not within 3°C (5°F), refer to «Temperature vs Resistance - Intake Air Temperature (IAT) Sensor»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction-2-of-2__temperature-vs-resistance-intake-air) .
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines that a condition exists. If the temperature is more than the specified value, test for a condition in the circuits of the IAT sensor.
2. 4: This step isolates the condition. If the temperature is less than the specified value, the ECM and the signal circuit of the IAT sensor are OK.

DTC P0112

The intake air temperature (IAT) sensor is an integral part of the mass air flow (MAF) sensor. The IAT sensor is a variable resistor that measures the temperature of the intake air. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and supplies a ground to the low reference circuit. If the ECM detects a high IAT signal voltage, which is a low temperature indication, this DTC sets.

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

DTC P0113

This diagnostic procedure supports the following DTC

DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage

1. The engine run time is more than 3 minutes.
2. The engine is idling for more than 10 seconds.
3. DTC P0113 runs continuously once the above conditions are met.

1. The ECM detects that the intake air temperature is less than -42°C (-43.6°F) and remains steady within 3°C (5.4°F) during an air flow increase of more than 999 grams. The scan tool is limited to -40°C (-40°F), so the diagnostic procedure uses -39°C (-38°F) to determine if there is an IAT condition.
2. The condition exists for more than 4 seconds

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0113

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. Use the Temperature vs Resistance table in order to test the IAT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in a driveability condition. If the engine has sat overnight, the intake air temperature and the engine coolant temperature values should display within a few degrees. If the temperatures are not within 3°C (5°F), refer to «Temperature vs Resistance - Engine Coolant Temperature (ECT) Sensor»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction-2-of-2__temperature-vs-resistance-engine-coolant) .
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines that a condition exists. If the temperature is less than the specified value, test for a condition in the circuits of the IAT sensor.
2. 5: This step tests for high resistance in the low reference circuit of the MAF/IAT sensor. The MAF sensor and the IAT sensor share the low reference circuit. If there is a condition with the low reference circuit, a MAF and IAT sensor DTC may set. The ECM must be completely powered down to obtain an accurate resistance reading. It may take up to 30 minutes for the ECM to power down after the ignition key is removed. Removal of the ECM fuse or the PCM/ETC fuse, allows the ECM to power down completely.
3. 6: This step tests the low reference circuit for a short to voltage. The control module or the sensor may be damaged if the circuit is shorted to battery voltage. Ensure that a short to voltage is repaired before replacing any components.
4. 11: Inspect the MAF/IAT sensor connector for water intrusion, corrosion and bent or damaged terminals.
5. 12: Inspect the ECM connectors for water intrusion, corrosion and bent or damaged terminals.

DTC P0113

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and supplies a ground to the low reference circuit. If the ECM detects a low ECT signal voltage, which is a high temperature indication, this DTC sets.

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

DTC P0117

This diagnostic procedure supports the following DTC

DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

1. The engine is operating.
2. The start up intake air temperature (IAT) is less than 72°C (161°F). OR
3. The engine is operating.
4. The start up IAT is more than 72°C (161°F).
5. The engine run time is more than 59 seconds.
6. DTC P0117 runs continuously once the above condition is met.

The ECM detects that the engine coolant temperature is more than 140°C (284°F) for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0117

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. An overheating condition may cause this DTC to set.
3. After starting the engine, the ECT should rise steadily to about 90°C (194°F) then stabilize when the thermostat opens.
4. Use the Temperature vs Resistance table in order to test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in a driveability condition. If the engine has sat overnight, the engine coolant temperature and the intake air temperature values should display within a few degrees. If the temperatures are not within 3°C (5.4°F), refer to «Temperature vs Resistance - Engine Coolant Temperature (ECT) Sensor»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction-2-of-2__temperature-vs-resistance-engine-coolant) .
5. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers in the diagnostic table.

1. 2: This step determines that a condition exists. If the temperature is more than the specified value, test for a condition in the circuits of the ECT sensor.
2. 4: This step isolates the condition. If the temperature is less than the specified value, the ECM and the signal circuit of the ECT sensor are OK.

DTC P0117

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and supplies a ground to the low reference circuit. If the ECM detects a high ECT signal voltage, which is a low temperature indication, this DTC sets.

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

DTC P0118

This diagnostic procedure supports the following DTC

DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

1. The ignition is ON or the engine is operating.
2. DTC P0118 runs continuously once the above condition is met.

The ECM detects that the intake air temperature is less than -42°C (-43.6°F) for more than 4 seconds. The scan tool is limited to -40°C (-40°F), so the diagnostic procedure uses -39°C (-38°F) to determine if there is an IAT condition.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0118

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. Use the Temperature vs Resistance table in order to test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in a driveability condition. If the engine has sat overnight, the engine coolant temperature and the intake air temperature values should display within a few degrees. If the temperatures are not within 3°C (5°F), refer to «Temperature vs Resistance - Engine Coolant Temperature (ECT) Sensor»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-introduction-2-of-2__temperature-vs-resistance-engine-coolant) .
3. After starting the engine, the ECT should rise steadily to about 90°C (194°F) then stabilize when the thermostat opens.
4. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers in the diagnostic table.

1. 5: This step tests for high resistance in the low reference circuit of the ECT sensor. The ECM must be completely powered down to obtain an accurate resistance reading. It may take up to 30 minutes for the ECM to power down after the ignition key is removed. Removal of the ECM fuse or the PCM/ETC fuse, allows the ECM to power down completely.
2. 6: This step is testing the low reference circuit for a short to voltage or for a low reference circuit that is open. If the low reference circuit within the ECM is open or if the low reference circuit is open between the ECM and the splice, a voltage of 3-5 volts will be measured on the DMM.
3. 7: This step isolates if there is a circuit that is shorted to voltage or if the low reference circuit is open internally or externally of the ECM. If there is no voltage on the low reference circuit after disconnecting all the sensors, the low reference circuit is open.

DTC P0118

The throttle body assembly contains 2 throttle position (TP) sensors. The TP sensors are mounted to the throttle body assembly and are not serviceable. The TP sensors provide a signal voltage that changes relative to throttle blade angle. The engine control module (ECM) supplies the TP sensors with a common 5-volt reference circuit, a common low reference circuit and 2 independent signal circuits.

The TP sensors have opposite functionality. TP sensor 1 signal voltage increases from below 1 volt at idle to above 4 volts at wide open throttle (WOT). TP sensor 2 signal voltage decreases from above 4 volts at idle to below 1 volt at WOT.

The ECM compares the signal of the TP sensor 1 and TP sensor 2 through the entire range. If the ECM detects a predetermined difference between sensor 1 and sensor 2 or a predetermined difference from the predicted range, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0121 Throttle Position (TP) Sensor 1 Performance

1. The ignition 1 voltage is more than 7 volts.
2. The TP sensor 1 voltage is between 0.18-4.6 volts.
3. DTC P0121 runs continuously once the above conditions are met.

1. The TP sensor 1 disagrees more than 9 percent from TP sensor 2.
2. The TP sensor 1 disagrees more than 9 percent from the predicted value.
3. The above conditions are met for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0121

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. If there is a condition with the TP sensors the ECM defaults to reduced power mode for the entire ignition cycle, even if the condition is corrected.
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step verifies that a condition exists. If there is a condition with a TP sensor circuit, the scan tool will display Disagree.
2. 5: This step tests for high resistance in the 5-volt reference circuit of the TP sensors. If the DMM does not display more than the specified voltage there is high resistance in the circuit.
3. 8: This step tests for high resistance in the low reference circuit of the TP sensor. The ECM must be completely powered down to obtain an accurate resistance reading. It may take up to 30 minutes for the ECM to power down after the ignition key is removed. Removal of the ECM fuse or the PCM/ETC fuse, allows the ECM to power down completely.

DTC P0121

The throttle body assembly contains 2 throttle position (TP) sensors. The TP sensors are mounted to the throttle body assembly and are not serviceable. The TP sensors provide a signal voltage that changes relative to throttle blade angle. The engine control module (ECM) supplies the TP sensors with a common 5-volt reference circuit, a common low reference circuit and 2 independent signal circuits.

The TP sensors have opposite functionality. TP sensor 1 signal voltage increases from below 1 volt at idle to above 4 volts at wide open throttle (WOT). TP sensor 2 signal voltage decreases from above 4 volts at idle to below 1 volt at WOT.

If the ECM detects TP sensor 1 signal voltage is too low, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0122 Throttle Position (TP) Sensor 1 Circuit Low Voltage

1. The ignition is ON, with the engine OFF or the engine is operating.
2. The ignition 1 voltage is more than 7 volts.
3. DTC P0122 runs continuously once the above conditions are met.

The ECM detects the TP sensor 1 signal voltage is less than 0.18 volts for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0122

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. If there is a condition with the TP sensors the ECM defaults to reduced power mode for the entire ignition cycle, even if the condition is corrected.
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step verifies that a condition exists.
2. 4: The TP sensors share a 5-volt reference circuit. If both DTCs P0122 and P0222 set, test for a condition in the 5-volt reference circuit.
3. 5: This step tests for a condition in the 5-volt reference circuit of the TP sensor. If the DMM displays less 4.8 volts test for a high resistance, an open or a short to ground in the circuit.
4. 6: This step tests the signal 1 circuit of the TP sensor. If the TP sensor 1 voltage parameter is not 4.8-5.2 volts, test for a condition in the signal 1 circuit.

DTC P0122

The throttle body assembly contains 2 throttle position (TP) sensors. The TP sensors are mounted to the throttle body assembly and are not serviceable. The TP sensors provide a signal voltage that changes relative to throttle blade angle. The engine control module (ECM) supplies the TP sensors with a common 5-volt reference circuit, a common low reference circuit and 2 independent signal circuits.

The TP sensors have opposite functionality. The TP sensor 1 signal voltage increases from below 1 volt at idle to above 4 volts at wide open throttle (WOT). The TP sensor 2 signal voltage decreases from above 4 volts at idle to below 1 volt at WOT.

If the ECM detects TP sensor 1 signal voltage is too high, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0123 Throttle Position (TP) Sensor 1 Circuit High Voltage

1. The ignition is ON, with the engine OFF or the engine is operating.
2. The ignition 1 voltage is more than 7 volts.
3. DTC P0123 runs continuously once the above conditions are met.

The ECM detects the TP sensor 1 signal voltage is more than 4.6 volts for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0123

1. Use the J 35616 GM Approved Terminal Test Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. If there is a condition with the TP sensors the ECM defaults to reduced power mode for the entire ignition cycle, even if the condition is corrected.
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step verifies that a condition exists.
2. 5: This step tests the signal circuit for a short to voltage. If the scan tool displays a voltage after the TP sensor is disconnected, the circuit is shorted to a voltage.
3. 7: This step tests for high resistance in the low reference circuit of the TP sensor. The ECM must be completely powered down to obtain an accurate resistance reading. It may take up to 30 minutes for the ECM to power down after the ignition key is removed. Removal of the ECM fuse or the PCM/ETC fuse, allows the ECM to power down completely.
4. 8: This step tests the low reference circuit for a short to voltage.

DTC P0123

The engine control module (ECM) monitors the temperature of the engine coolant for engine control and as an enabling criteria for some diagnostics. The amount of air flow into an engine is proportional to the amount of heat an engine generates. The ECM monitors the amount of air flow into the engine to calculate engine coolant temperature (ECT). The ECM uses the calculated temperature to determine if the engine has warmed up to the closed loop temperature. If the coolant temperature does not increase normally or does not reach the closed loop temperature, diagnostics that use the ECT as enabling criteria, may not run when expected. If the ECT fails to reach the closed loop temperature, before a predetermined amount of air flow enters the engine, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0125 Engine Coolant Temperature (ECT) Insufficient for Closed Loop Fuel Control

1. DTCs P0112, P0113, P0117, P0118, P0480, P0481, P0691, P0692, P0693 and P0694 are not set.
2. The engine is operating.

The actual ECT is not within 10°C (18°F) of the calculated ECT after approximately 8 minutes, which depends on the amount of air flow into the engine after start-up.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0125

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers in the diagnostic table.

1. 3: This step tests for excess resistance in the ECT circuit.
2. 4: This step tests for a skewed sensor through the range of temperatures affecting this DTC.

DTC P0125

The engine control module (ECM) monitors the temperature of the engine coolant for engine control and as an enabling criteria for some diagnostics. The amount of air flow into an engine is proportional to the amount of heat an engine generates. The ECM monitors the amount of air flow into the engine to calculate engine coolant temperature (ECT). The ECM uses the calculated temperature to determine if the engine has warmed up to the thermostat regulating temperature. If the coolant temperature does not increase normally or does not reach regulating temperature of the thermostat, diagnostics that use the ECT as enabling criteria, may not run when expected. If the engine coolant temperature fails to reach the thermostat regulating temperature, before a predetermined amount of air flow enters the engine, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0128 Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature

1. Before the ECM can report DTC P0128 failed, DTC P0117 must run and pass.
2. DTCs P0101, P0102, P0103, P0112, P0113, P0118 and P0700 are not set.
3. The engine speed is more than 960 RPM.
4. The ECT is less than 71°C (160°F) at start up.
5. The calculated ambient air temperature is more than -11°C (-12°F) and less than 45°C (113°F).
6. The vehicle speed is more than 15 km/h (9 mph).
7. The air flow coming into the engine has accumulated too more than 2,000 grams.
8. DTC P0128 runs continuously once the above conditions have been met for approximately 15 minutes.

1. The ECM detects that the actual engine coolant temperature (ECT) is 10°C (18°) less than the calculated ECT.
2. The condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0128

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step tests for excessive resistance in the ECT circuit.
2. 4: This step tests for a skewed sensor through the range of temperatures that affects this DTC.

DTC P0128

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio. If the ECM detects that the HO2S signal voltage is not within range, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0130 HO2S Circuit Sensor 1

1. The engine is operating.
2. The ignition 1 voltage is between 10.7-18 volts.
3. DTC P0130 runs continuously once the above conditions are met.

1. The ECM detects that the HO2S signal voltage is out of range.
2. The above condition exists for less than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0130

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. The front wide band sensors do not toggle or switch like a switching HO2S. The front HO2S signals will be relatively stable for an idling engine.
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .
4. The following table illustrates the typical voltages for the HO2S circuits

HO2S Voltages

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines if the condition exists. If there is a condition with the HO2S circuits, the ECM commands open loop for the applicable sensor.
2. 4: This step tests for a bias voltage across the reference voltage circuit and the low reference circuit of the HO2S. The bias voltage that you are measuring, is the voltage difference between the reference voltage circuit and the low reference circuit. If there is a condition with the reference voltage circuit or the low reference circuit of the HO2S, the bias voltage will not be within the specified range, which indicates there is a condition with the circuits.
3. 5: This step tests the input pumping current circuit and the pump current circuit of the HO2S. The input pumping current circuit and the pump current circuit are connected internally within the ECM. If there is a condition with one of the circuits, the other circuit will be affected.

DTC P0130

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio. If the ECM detects that the HO2S signal voltage is low, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0131 HO2S Circuit Low Voltage Sensor 1

1. The engine is operating.
2. The ignition 1 voltage is between 10.7-18 volts.
3. DTC P0131 runs continuously once the above conditions are met for more than 2 seconds.

1. The internal ECM HO2S voltage is less than a threshold.
2. The above condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0131

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. The front wide band sensor does not toggle or switch like a switching HO2S. The front HO2S signal will be relatively stable for an idling engine.
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .
4. The following table illustrates the typical voltages for the HO2S circuits

HO2S Voltages

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines if the condition exists. If there is a short to ground condition with the HO2S circuits, the ECM commands open loop for the applicable sensor.
2. 4: This step tests for a bias voltage across the reference voltage circuit and the low reference circuit of the HO2S. The bias voltage that you are measuring, is the voltage difference between the reference voltage circuit and the low reference circuit. If the reference voltage circuit or the low reference circuit of the HO2S is shorted to ground, the bias voltage will be above 1.5 volts, which indicates there is a condition with the circuits.
3. 5: This step tests for a short to ground on the input pumping current circuit and the pump current circuit of the HO2S. The input pumping current circuit and the pump current circuit are connected internally within the ECM. If one of the circuits are shorted to ground, the other circuit will be affected. If you were to probe both circuits with a test lamp, the circuit that illuminates the test lamp brighter, is the circuit that is shorted to ground.

DTC P0131

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio.

This diagnostic procedure supports the following DTC

DTC P0132 HO2S Circuit High Voltage Sensor 1

1. The engine is operating.
2. The ignition 1 voltage is between 10.7-18 volts.
3. DTC P0132 runs continuously once the above conditions are met for more than 2 seconds.

1. The internal ECM HO2S voltage is more than a threshold.
2. The above condition exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0132

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. The front wide band sensors do not toggle or switch like a switching HO2S. The front HO2S signals will be relatively stable for an idling engine.
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .
4. This DTC sets if the heater control circuit is shorted to any other HO2S circuit. The following table illustrates the typical voltages for the HO2S circuits.

HO2S Voltages

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines if the condition exists. If there is a short to voltage condition with the HO2S circuits, the ECM commands open loop for the applicable sensor.
2. 4: This step tests for a bias voltage across the reference voltage circuit and the low reference circuit of the HO2S. The bias voltage that you are measuring, is the voltage difference between the reference voltage circuit and the low reference circuit. If the reference voltage circuit or the low reference circuit of the HO2S is shorted to a voltage, the bias voltage will be more than the specified value, which indicates there is a condition with the circuits.
3. 5: This step tests for a short to voltage on the input pumping current circuit and the pump current circuit of the HO2S. The input pumping current circuit and the pump current circuit are connected internally within the ECM. If one of the circuits are shorted to voltage, the other circuit will be affected.
4. 7: This step isolates if the condition is with the reference voltage circuit or the low reference circuit. If the voltage is less than the specified value, the condition is with low reference circuit.
5. 11: This step inspects the harness connector for water intrusion, corrosion and bent or damaged pins.
6. 12: This step inspects the harness connector for water intrusion, corrosion and bent or damaged pins.

DTC P0132

The wide band heated oxygen sensor (HO2S) measures the amount of oxygen in the exhaust system and provides more information than the switching style HO2S. The wide band sensor consists of an oxygen sensing cell, an oxygen pumping cell and a heater. The exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The engine control module (ECM) supplies a voltage to the HO2S and uses this voltage as a reference to the amount of oxygen in the exhaust system. An electronic circuit within the ECM controls the pump current through the oxygen pumping cell in order to maintain a constant voltage in the oxygen sensing cell. The ECM monitors the voltage variation in the sensing cell and attempts to keep the voltage constant by increasing or decreasing the amount of current flow or oxygen ion flow, to the pumping cell. By measuring the amount of current required to maintain the voltage in the sensing cell, the ECM can determine the concentration of oxygen in the exhaust. The HO2S voltage is displayed as a lambda value. A lambda value of 1 is equal to a stoichiometric air fuel ratio of 14.7:1. Under normal operating conditions, the lambda value will remain around 1. When the fuel system is lean, the oxygen level will be high and the lambda signal will be high or more than 1. When the fuel system is rich, the oxygen level will be low and the lambda signal will be low or less than 1. The ECM uses this information to maintain the correct air/fuel ratio.

This diagnostic procedure supports the following DTC

DTC P0133 HO2S Slow Response Sensor 1

1. Before the ECM can report DTC P0133 failed, DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0335, P0336, P0338 and P2237 must run and pass.
2. DTCs P0030, P0031, P0032, P0053, P0130, P0131, P0132, P0135, P0442, P0443, P0446, P0455, P0458, P0459 P167A, P2096, P2097, P2231, P2243, P2251, P2297 and P2626 are not set.
3. The HO2S is at operating temperature.
4. The fuel trim is enabled.
5. The HO2S is between 0.94-1.06 lambda.
6. The engine speed is between 1,480-2,520 RPM.
7. The volumetric efficiency is between 15.7-50.2 percent.
8. The change in volumetric efficiency is less than 3 percent.
9. The evaporative emission (EVAP) purge is not active or the ECM determines the EVAP hydrocarbon (HC) concentration is less than a predetermined threshold.
10. The long term fuel trim correction is active.
11. DTC P0133 runs continuously once the above conditions are met for approximately 10 minutes.

1. The ECM has determined that the dynamic value of the affected HO2S is less than a predetermined threshold.
2. The above condition is exists for more than 4 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
2. A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
3. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
4. Clear the MIL and the DTC with a scan tool.

The following table illustrates the ECM connector locations

DTC P0133

1. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
2. The front wide band sensors do not toggle or switch like a switching HO2S. The front HO2S signal will be relatively stable for an idling engine.
3. For an intermittent condition, refer to «Intermittent Conditions»(/buick/lacrosse/i-2004-2009/remont/testing-diagnostics/#engine-control-system-36l-ly7-troubleshooting__intermittent-conditions) .
4. The following table illustrates the typical voltages for the HO2S circuits

HO2S Voltages

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step determines if the condition exists.
2. 4: This step determines if the fuel system is contaminated.

DTC P0133

See also:
• Intermittent Conditions
• Diagnostic System Check - Vehicle
• Camshaft Timing Drive Chain Alignment Diagram (W/Primary Inverted Tooth (IT) Chain)
• Camshaft Timing Drive Components Cleaning and Inspection
• Diagnostic Trouble Code (DTC) List - Vehicle
• Engine Controls Schematics
• Engine Control Module (ECM) Connector End Views
• Engine Controls Connector End Views
• Circuit Testing
• Wiring Repairs
• Testing for Intermittent Conditions and Poor Connections
• Connector Repairs
• Control Module References
• Fluid and Lubricant Recommendations
• Measuring Voltage Drop
• Camshaft Position (CMP) Actuator Replacement - Bank 1 (Right) Intake
• Temperature vs Resistance - Intake Air Temperature (IAT) Sensor
• Temperature vs Resistance - Engine Coolant Temperature (ECT) Sensor
• DISENGAGING CONNECTORS NOTICE
• Loss of Coolant
• Thermostat Diagnosis (LY7)
• Road Test Caution
• Fuel Injector Balance Test with Special Tool
• Exhaust Leakage
• Oil Consumption Diagnosis
• DTC P0102