Engine Controls - 2.2l (DTC p0451 to p2101) Chevrolet Cobalt I

System Description

The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum. The controller uses this FTP signal to determine atmospheric pressure for use in the engine-off small leak test, DTC P0442. Before using this signal as an atmospheric reference it must first be re-zeroed. If the FTP signal is out of range during the re-zero procedure, this DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P0451 Fuel Tank Pressure (FTP) Sensor Performance

Conditions for Running the DTC

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

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC

1. The control module turns OFF the MIL after 3 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 DTC with a scan tool.

Diagnostic Aids

1. A restriction in the EVAP canister or vent lines could prevent fuel vapor pressure from bleeding off fast enough. If the vent system cannot bleed off pressure fast enough, the re-zero procedure may not complete successfully, which could cause this code to set.
2. By using the purge solenoid command on a scan tool, vacuum can be applied to the system instead of pressure. With the EVAP canister vent solenoid valve open and the EVAP canister purge solenoid valve commanded to 100 percent, the vacuum should not increase to more than 6 inches H2O.
3. An EVAP canister filter that is restricted can cause this DTC to set. Refer to «Evaporative Emission (EVAP) Canister Filter Replacement»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-22l-introduction) .
4. Ensure that the reference port on the FTP sensor is unobstructed.

DTC P0451

Circuit Description

The fuel tank pressure (FTP) sensor measures the difference between the air pressure or vacuum in the Evaporative Emission (EVAP) System, and the outside air pressure. The engine control module (ECM) supplies the following circuits to the FTP sensor

1. A 5-volt reference circuit
2. A low reference circuit
3. A signal circuit

The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the ECM detects that the FTP sensor signal voltage is less than 0.1 volt, DTC P0452 sets.

The following table illustrates the relationship between the FTP sensor signal voltage and the EVAP system pressure/vacuum.

DTC P0452

This diagnostic procedure supports the following DTC

P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage

DTC P0452 runs once per ignition cycle when the engine is running.

1. The FTP voltage is less than 0.1 volt.
2. The above condition is present for more than 15 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 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 rear body pass-through connector may be a convenient point for testing.

DTC P0452

The fuel tank pressure (FTP) sensor measures the difference between the air pressure or vacuum in the Evaporative Emission (EVAP) System, and the outside air pressure. The engine control module (ECM) supplies the following circuits to the FTP sensor

1. A 5-volt reference circuit
2. A low reference circuit
3. A signal circuit

The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the ECM detects that the FTP sensor signal voltage is more than 4.9 volts, DTC P0453 sets.

The following table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.

DTC P0453

This diagnostic procedure supports the following DTC

DTC P0453 Fuel Tank Pressure (FTP) Sensor Circuit Voltage

DTC P0453 runs once per ignition cycle when the engine is running.

1. The FTP sensor voltage is more than 4.9 volts.
2. The condition is are present for more than 15 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

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 P0453

The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum. This DTC will set if the control module detects an intermittent signal from the FTP that would prevent the engine-off small leak test, DTC P0442, from running.

This diagnostic procedure supports the following DTC

DTC P0454 Fuel Tank Pressure (FTP) Sensor Circuit Intermittent

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

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

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the MIL after 3 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 DTC with a scan tool.

1. This diagnostic is designed to detect an unexpected abrupt voltage signal change from the FTP.
2. Scan tool output controls, snapshot, and plot functions can help detect erratic sensor response. To look at the sensor signal under vacuum conditions, use snapshot and the purge/seal function to capture data while commanding purge to 30 percent, and then plot the data to look for erratic sensor operation. A similar inspection can be done for the pressure side of the sensor range by applying pressure with the J 41413-200 Evaporative Emissions System Tester (EEST) while taking a snapshot.
3. Ensure that the reference port on the FTP sensor is unobstructed.

DTC P0454

The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge solenoid valve OPEN and the EVAP vent solenoid valve CLOSED. This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge solenoid valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.

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

DTC P0455

This diagnostic procedure supports the following DTC

DTC P0455 Evaporative Emission (EVAP) System Large Leak

1. DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0452, P0453, P0502, P0601, P0602, P0606, P0641 are not set.
2. The engine is running.
3. The ignition voltage is between 11-18 volts.
4. The barometric pressure (BARO) is more than 74 kPa.
5. The fuel level is between 15-85 percent.
6. The start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F).
7. The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
8. The start-up ECT and IAT are within 8°C (14.4°F) of each other.
9. DTC P0455 runs once per cold start within 10 minutes of start-up.

The EVAP system is not able to achieve or maintain vacuum for up to 4 minutes during the diagnostic test.

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 3 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. A loose, missing, incorrect, or damaged fuel fill cap may cause this DTC to set.
2. A leak in the EVAP system can be verified by the use of a flow meter on the J 41413-200 Evaporative Emissions System Tester (EEST). Refer to the J 41413-200 operation manual for flow meter use.
3. To help locate intermittent leaks, use the J 41413-200 to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. Introducing smoke in 15-second intervals will allow less pressure into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
4. A temporary blockage in the EVAP canister purge solenoid valve, purge pipe or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.
5. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .
6. Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
7. For intermittent conditions, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-22l-troubleshooting-diagnosis__intermittent-conditions) .

Test Description

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

1. 6: This step verifies proper operation of the FTP sensor.
2. 7: A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6-7 inches of H2O.

DTC P0455

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

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

DTC P0496

This diagnostic procedure supports the following DTC

DTC P0496 Evaporative Emission (EVAP) System Flow During Non-Purge

1. DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0442, P0446, P0452, P0453, P0502, P0601, P0602, P0606, P0641 are not set.
2. The ignition voltage is between 11-18 volts.
3. The barometric pressure (BARO) is more than 74 kPa.
4. The fuel level is between 15-85 percent.
5. The engine coolant temperature (ECT) is between 5-32°C (41-90°F).
6. The intake air temperature (IAT) is between 5-32°C (41-90°F).
7. The start-up ECT and IAT are within 9°C (16°F) of each other.
8. The vehicle speed sensor (VSS) is less than 121 km/h (75 mph).
9. The FTP sensor is less than -2.5 inches H2O at ignition ON.
10. DTC P0496 runs once per cold start for 96 seconds.

The control module detects vacuum greater than 4 inches H2O, during a non-purge condition 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 3 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. An intermittent condition could be caused by an improperly installed or damaged EVAP canister purge solenoid valve or an EVAP canister purge solenoid valve that is temporarily stuck open
2. For intermittent conditions, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-22l-troubleshooting-diagnosis__intermittent-conditions) .

DTC P0496

The throttle actuator control (TAC) motor is controlled by the engine control module (ECM). The DC motor located in the throttle body drives the throttle plate. In order to decrease idle speed, the ECM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the ECM commands the throttle plate open allowing more air to pass the throttle plate. If the actual idle RPM does not match the desired idle RPM within a calibrated time, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0506 Idle Speed Low

1. DTCs P0068, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0130, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0300, P0336, P0442, P0446, P0452, P0453, P0641, P0651, P1516, P2101, P2135, P2176 are not set.
2. The engine is operating for at least 40 seconds.
3. The engine coolant temperature (ECT) is between -40 and +110°C (-40 and +230°F).
4. The intake air temperature (IAT) is more than -18°C (+10°F).
5. The barometric pressure (BARO) is more than 70 kPa.
6. The system voltage is between 10.5-18 volts.
7. The engine is at idle for more than 2 seconds.
8. DTC P0506 runs continuously when the above conditions are met.

1. The actual idle speed is approximately 100 RPM lower than the desired idle speed.
2. The above condition is present for 9 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 3 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 number below refers to the step number on the diagnostic table.

1. 2: This test determines whether the engine can achieve the commanded RPM. If the engine does not reach the commanded RPMs, the test determines whether the RPM is too high or too low.

DTC P0506

The throttle actuator control (TAC) motor is controlled by the engine control module (ECM). The DC motor located in the throttle body drives the throttle plate. In order to decrease idle speed, the ECM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the ECM commands the throttle plate open allowing more air to pass the throttle plate. If the actual idle RPM does not match the desired idle RPM within a calibrated time, this DTC sets.

This diagnostic procedure supports the following DTC

DTC P0507 Idle Speed High

1. DTCs P0068, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0122, P0123, P0125, P0130, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0300, P0336, P0442, P0446, P0452, P0453, P0641, P0651, P1516, P2101, P2135, P2176 are not set.
2. The engine is operating for at least 40 seconds.
3. The engine coolant temperature (ECT) is between -40 and +110°C (-40 and +230°F).
4. The intake air temperature (IAT) is more than -18°C (0°F).
5. The barometric pressure (BARO) is more than 70 kPa.
6. The system voltage is between 10.5-18 volts.
7. The engine is at idle for more than 2 seconds.
8. DTC P0507 runs continuously when the above conditions are met.

1. The actual idle speed is approximately 100 RPM greater than the desired idle speed.
2. The above condition is present for 9 seconds.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 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 number below refers to the step number on the diagnostic table.

1. 2: This test determines whether the engine can achieve the commanded RPM. If the engine does not reach the commanded RPMs, the test determines whether the RPM is too high or too low.

DTC P0507

Description

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

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC P0601 Control Module Read Only Memory (ROM)
2. DTC P0602 Control Module Not Programmed
3. DTC P0603 Control Module Long Term Memory Reset
4. DTC P0606 Control Module Internal Performance
5. DTC P1621 Control Module Long Term memory Performance
6. DTC P2610 Control Module Ignition Off Timer Performance

The number below refers to the step number on the diagnostic table.

1. 2: A DTC P0602 indicates that the ECM is not programmed.

DTC P0601-P0607, P060E, P1600, P1621, P1627, P1681, P1683, or P2610

The engine control module (ECM) uses the 5-volt reference circuit as a sensor feed to the following sensors

1. The air conditioning (A/C) pressure sensor
2. The throttle position (TP) sensor 1
3. The accelerator pedal position (APP) sensor 1
4. The fuel tank pressure (FTP) sensor

The ECM monitors the voltage on the 5-volt reference circuit. If the voltage is out of tolerance, the ECM will set DTC P0641.

This diagnostic procedure supports the following DTC

DTC P0641 5-Volt Reference 1 Circuit

1. DTCs P0601, P0602, P0604, P0606, P1621, P2610 are not set.
2. The ignition is in Unlock/Accessory, Run, or Crank.
3. The ignition voltage is greater than 10.9 volts.
4. DTC P0641 runs continuously when the above conditions are met.

1. The ECM detects a voltage out of tolerance condition on the 5-volt reference circuit.
2. The above condition is present for longer than one second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 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.

DTC P0641

The malfunction indicator lamp (MIL) is located on the instrument panel cluster (IPC). The MIL informs the driver that an emission system fault has occurred and that the engine control system requires service. The control module monitors the MIL control circuit for conditions that are incorrect for the commanded state of the MIL. If the control module detects an improper voltage on the MIL control circuit, DTC P0650 will set.

This diagnostic procedure supports the following DTC

DTC P0650 Malfunction Indicator Lamp (MIL) Control Circuit

DTC P0650 runs continuously when the ignition is ON.

The control module detects that the commanded state of the MIL driver and the actual state of the control circuit do not match for more than one second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 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 numbers below refer to the step numbers on the diagnostic table.

1. 4: This step tests for a short to ground in the MIL control circuit. With the engine control module (ECM) disconnected and the ignition is ON, the MIL should be OFF.
2. 5: This step tests for a short to voltage on the MIL control circuit. With the fuse removed, there should be no voltage on the MIL control circuit.

DTC P0650

The engine control module (ECM) uses the 5-volt reference circuit as a sensor feed to the following sensors

1. The manifold absolute pressure (MAP)
2. The throttle position (TP) sensor 2
3. The accelerator pedal position (APP) sensor 2

The ECM monitors the voltage on the 5-volt reference circuit. If the voltage is out of tolerance, the ECM will set DTC P0651.

This diagnostic procedure supports the following DTC

DTC P0651 5-Volt Reference 2 Circuit

1. DTCs P0601, P0602, P0604, P0606, P1621, P2610 are not set.
2. The ignition is ON.
3. The ignition voltage is greater than 10.9 volts.
4. DTC P0651 runs continuously when the above conditions are met.

1. The PCM detects a voltage out of tolerance condition on the 5-volt reference circuit.
2. The above condition is present for longer than 1 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 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.

DTC P0651

The intake flow rationality diagnostic provides the within-range rationality check for the mass air flow (MAF), manifold absolute pressure (MAP), and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing 4 separate models for the intake system.

1. The throttle model describes the flow through the throttle body and is used to estimate the MAF through the throttle body as a function of barometric pressure (BARO), TP, intake air temperature (IAT), and estimated MAP.
2. The first intake manifold model describes the intake manifold and is used to estimate MAP as a function of the MAF into the manifold from the throttle body and the MAF out of the manifold caused by engine pumping. The flow into the manifold from the throttle uses the MAF estimate calculated from the above throttle model.
3. The second intake manifold model is identical to the first intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input.
4. A fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model.

The estimates of MAF and MAP obtained from this system of models and calculations are then compared to the actual measured values from the MAF, MAP, and the TP sensors and to each other to determine the appropriate DTC to fail. The following table illustrates the possible failure combinations and the resulting DTC or DTCs.

DTC P1101

If the engine control module (ECM) detects that the actual measured airflow from MAF, MAP, and TP is not within range of the calculated airflow that is derived from the system of models, DTC P1101 sets.

This diagnostic procedure supports the following DTC

DTC P1101 Intake Air Flow System Performance

1. DTCs P0102, P0103, P0112, P0113, P0107, P0108, P0117, P0118, P0335, P0336 are not set.
2. The engine speed is between 400-6,400 RPM.
3. The IAT Sensor parameter is between -7°C and +125°C (19-257°F).
4. The ECT Sensor parameter is between 70-125°C (158-257°F).
5. This DTC runs continuously within the enabling conditions.

The ECM detects that the actual measured airflow from MAF, MAP, and TP is not within range of the calculated airflow that is derived from the system of models for more than 0.5 second.

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 3 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. Any condition that can cause the MAF, MAP, and TP sensors to be shifted in value at the same time will cause this DTC to set.
2. Inspect the harness of the MAF sensor to verify that it is not routed too close to the following components: Any aftermarket accessories-Refer to «Checking Aftermarket Accessories»(/chevrolet/cobalt/i-2004-2010/remont/electrical-component-locations/#wiring-systems-electrical-power-management__checking-aftermarket-accessories) . Any solenoids Any relays Any motors
3. A wide open throttle acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 3-6 g/s at idle to 120 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
4. A skewed or stuck engine coolant temperature (ECT) or IAT sensor will cause the calculated models to be inaccurate and may cause this DTC to run when it shouldn't.
5. A steady or intermittent high resistance of 15 ohms or more on the ignition 1 voltage circuit will cause the MAF sensor values to be skewed high by up to 60 g/s, and may cause this DTC to set. A high resistance will cause a driveability concern before this DTC sets.
6. The BARO that is used by the ECM to calculate the air flow models is initially based on the MAP sensor at key ON. When the engine is running, the ECM will continually update the BARO value near wide open throttle using the MAP sensor and a calculation. A skewed MAP sensor will cause the calculated mass air flow value to be inaccurate and may result in a no start condition. With the ignition ON and the engine OFF, the MAP Sensor parameter varies with the altitude. 101 kPa is the approximate value near sea level. This value will decrease by approximately 3 kPa for every 305 meters (1,000 feet) of altitude.
7. A high resistance on the low reference circuit of the MAP sensor will skew the sensor value and may cause this DTC to set.
8. A short to battery voltage on the 5-volt reference circuit of the MAP sensor will cause this DTC to set.
9. If the condition is intermittent, refer to «Inducing Intermittent Fault Conditions»(/chevrolet/cobalt/i-2004-2010/remont/electrical-component-locations/#wiring-systems-electrical-power-management) and «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-22l-troubleshooting-diagnosis__intermittent-conditions) .

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

1. 5: This step will determine if any mechanical faults have caused this DTC to set.
2. 12: This voltage drop test will determine if high resistance has caused this DTC to set.
3. 14: This step verifies the voltage signal from the ECM to the MAF sensor connector.
4. 15: This step will determine if the ECM can accurately process the frequency signal that it receives from the MAF sensor.
5. 16: This step will determine if an abnormal resistance of less than 1,150 ohms has skewed the MAF sensor frequency signal.

DTC P1101

The manifold absolute pressure (MAP) sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by engine speed, throttle opening, air temperature, and barometric pressure (BARO). A diaphragm within the MAP sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine. The sensor translates this action into electrical resistance. The MAP sensor wiring includes 3 circuits. The engine control module (ECM) supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The ECM supplies a ground on a low reference circuit. The MAP sensor provides a signal voltage to the ECM, relative to the pressure changes, on the MAP sensor signal circuit. The ECM converts the signal voltage input to a pressure value.

Under normal operation the highest pressure that can exist in the intake manifold is equal to BARO. This occurs when the vehicle is operated at wide-open throttle (WOT) or when the ignition is on while the engine is off. Under these conditions, the ECM uses the MAP sensor to determine the current BARO. The lowest manifold pressures occur when the vehicle is idling or decelerating. MAP can range from 10 kPa, when pressures are low, to as much as 104 kPa when pressures are high, depending on the BARO. The ECM monitors the MAP sensor signal for pressure outside of the normal range. If the ECM detects that the MAP sensor pressure is intermittently high, DTC P1106 sets.

This diagnostic procedure supports the following DTC

DTC P1106 Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent High Voltage

1. DTCs P0641, P0651, P1516, P1680, P1681, P2101, P2120, P2125, P2135, P2138, P2176 are not set.
2. The engine has been running for a period of time that is determined by the start-up coolant temperature. The time ranges from 8 seconds at less than -30°C (-22°F) to 3 seconds at more than 30°C (86°F).
3. The throttle angle is less than 90 percent when the engine speed is less than 1,000 RPM. OR
4. The throttle angle is less than 98 percent when the engine speed is more than 1,000 RPM.
5. This DTC runs continuously within the enabling conditions.

The ECM detects that the MAP sensor pressure is intermittently more than 102 kPa.

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.

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.

The number below refers to the step number on the diagnostic table.

1. 3: This step attempts to pinpoint the location of the intermittent fault.

DTC P1106

The manifold absolute pressure (MAP) sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by engine speed, throttle opening, air temperature, and barometric pressure (BARO). A diaphragm within the MAP sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine. The sensor translates this action into electrical resistance. The MAP sensor wiring includes 3 circuits. The engine control module (ECM) supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The ECM supplies a ground on a low reference circuit. The MAP sensor provides a signal voltage to the ECM, relative to the pressure changes, on the MAP sensor signal circuit. The ECM converts the signal voltage input to a pressure value.

Under normal operation the highest pressure that can exist in the intake manifold is equal to BARO. This occurs when the vehicle is operated at wide-open throttle (WOT) or when the ignition is on while the engine is off. Under these conditions, the ECM uses the MAP sensor to determine the current BARO. The lowest manifold pressures occur when the vehicle is idling or decelerating. MAP can range from 10 kPa, when pressures are low, to as much as 104 kPa when pressures are high, depending on the BARO. The ECM monitors the MAP sensor signal for pressure outside of the normal range. If the ECM detects that the MAP sensor pressure is intermittently low, DTC P1107 sets.

This diagnostic procedure supports the following DTC

DTC P1107 Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent Low Voltage.

1. DTCs P0641, P0651, P1516, P1680, P1681, P2101, P2120, P2125, P2135, P2138, P2176 are not set.
2. The ignition is ON.
3. The throttle angle is more than 0 percent when the engine speed is less than 1,000 RPM. OR
4. The throttle angle is more than 9 percent when the engine speed is more than 1,000 RPM.
5. This DTC runs continuously within the enabling conditions.

The ECM detects that the MAP sensor pressure is intermittently less than 12 kPa.

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.

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.

The number below refers to the step number on the diagnostic table.

1. 3: This step attempts to pinpoint the location of the intermittent fault.

DTC P1107

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the IAT signal circuit. If the ECM detects an excessively high IAT signal voltage, indicating a low temperature, DTC P1111 sets.

This diagnostic procedure supports the following DTC

DTC P1111 Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage

1. DTCs P0101, P0102, P0103, P0117, P0118, P0502, P0503 are not set.
2. The engine run time is more than 10 seconds.
3. The vehicle speed sensor (VSS) indicates that vehicle speed is less than 1.6 km/h (1 mph).
4. The engine coolant temperature (ECT) is more than 50°C (122°F).
5. The mass air flow (MAF) is less than 12 g/s.
6. This DTC runs continuously within the enabling conditions.

The ECM detects that the IAT sensor parameter is less than -39°C (-38°F) intermittently for more than 5 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.

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.

The number below refers to the step number on the diagnostic table.

1. 6: This step tests for the proper operation of the circuit in the low voltage range.

DTC P1111

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the IAT signal circuit. If the ECM detects an excessively low IAT signal voltage, indicating a high temperature, DTC P1112 sets.

This diagnostic procedure supports the following DTC

DTC P1112 Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage.

1. DTCs P0117, P0118, P0502, P0503 are not set.
2. The engine run time is more than 10 seconds.
3. The vehicle speed sensor (VSS) indicates that vehicle speed is more than 40 km/h (25 mph).
4. The engine coolant temperature (ECT) is less than 110°C (230°F).
5. This DTC runs continuously within the enabling conditions.

The ECM detects that the IAT sensor parameter is more than 149°C (300°F) intermittently for more than 5 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.

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 P1112

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 a ground for the ECT low reference circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the ECT signal circuit. If the ECM detects an excessively low ECT signal voltage, which is a high temperature indication, DTC P1114 sets.

This diagnostic procedure supports the following DTC

DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage

1. The engine is running for more than 10 seconds. OR
2. The engine run time is less than 10 seconds when the intake air temperature (IAT) is less than 70°C (158°F).
3. This DTC runs continuously within the enabling conditions.

The ECM detects that the ECT sensor parameter is more than 149°C (300°F) intermittently for more than 5 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.

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 P1114

The engine coolant temperature (ECT) sensor is a variable resistor, that measures the temperature of the engine coolant. The ECT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and a ground for the ECT low reference circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the ECT signal circuit. If the ECM detects an excessively high ECT signal voltage, which is a low temperature indication, DTC P1115 sets.

This diagnostic procedure supports the following DTC

DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage

1. The engine is running for more than one minute. OR
2. The engine run time is less than one minute when the intake air temperature (IAT) is more than -7°C (+19°F).
3. This DTC runs continuously within the enabling conditions.

The ECM detects that the ECT sensor parameter is less than -39°C (-38°F) intermittently for more than 5 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.

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 P1115

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The engine control module (ECM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the ECM operates in Open Loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and Closed Loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream, low HO2S voltage indicates a lean exhaust stream. This diagnostic will only run once per ignition cycle. The ECM monitors the number of rich-to-lean and lean-to-rich transitions. If the ECM detects that the number of transitions were less than a specified value, DTC P1133 will set.

This diagnostic procedure supports the following DTC

DTC P1133 HO2S Insufficient Switching Sensor 1

1. DTCs P0037, P0038, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0130, P0133, P0137, P0138, P0140, P0171, P0172, P0300, P0336, P0340, P0341, P0455, P0500, P0601, P0602, P0606, P0641, P0722, P0723, P1134 are not set.
2. The Air Flow parameter is between 7-25 g/s.
3. The Engine Speed parameter is between 1,500-3,200 RPM.
4. The Loop Status parameter is closed.
5. DTC P1133 runs once per drive cycle when the above conditions are met for 100 seconds.

1. The ECM detects that the HO2S 1 Lean/Rich or the Rich/Lean transitions are less than a calibrated value.
2. DTC P1133 sets within 60 seconds when the above condition is met.

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 3 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.

DTC P1133

The commanded throttle position is compared to the actual throttle position based on accelerator pedal position (APP) and possibly other limiting factors. Both values should be within a calibrated range of each other. The engine control module (ECM) continuously monitors the commanded and actual throttle positions. This DTC sets if the values are greater than the calibrated range.

This diagnostic procedure supports the following DTC

DTC P1516 Throttle Actuator control (TAC) Module Throttle Actuator Position Performance

1. The ignition is ON.
2. The ignition voltage is greater than 8 volts.
3. The system is not in the Battery Save mode.
4. The engine is running.
5. DTC P0068 is not set.
6. DTC P1516 runs continuously when the above conditions are met.

1. The difference between the predicted and the actual throttle position is more than a calibrated amount.
2. The above condition is present for more than 0.5 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The ECM turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and passes.
2. A History DTC clears after 40 consecutive warm-up cycles in which there are no failures reported of this diagnostic or any other emission related diagnostic.
3. The scan tool clears the MIL/DTC.

1. The throttle valve are spring loaded to a slightly open position. This is referred to as the rest position.
2. The throttle valve should not be completely closed nor should they be open any more than the specified amount.
3. The throttle valve should move open and to the closed position without binding under the normal spring pressure.
4. The throttle should NOT be free to move open or closed WITHOUT spring pressure.
5. Replace the throttle body if any of these conditions are found.

1. The scan tool has the ability to operate the throttle control system using Special Functions. Actuate the throttle valve using the throttle blade control function located in the Throttle Actuator Control (TAC) System menu. This function will operate the throttle valve through the entire range in order to determine if the throttle body and system operate correctly.
2. Inspect for the following conditions: Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. Poor connections at the ECM or at the component-Inspect the harness connectors for a poor terminal to wire connection. Refer to «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cobalt/i-2004-2010/remont/electrical-component-locations/#wiring-systems-electrical-power-management__testing-for-intermittent-conditions-and-poor) in Wiring Systems for the proper procedure. For an intermittent condition, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-22l-troubleshooting-diagnosis__intermittent-conditions) .

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

1. 8: The throttle valve is spring loaded in a slightly open position and should move in either direction without binding. The throttle valve should always be under spring pressure.
2. 11: When the ignition is turned ON, the ECM operates the throttle control motor to verify the integrity of the system prior to start-up. This can be seen by the momentary flash of the test lamp as the ignition is turned ON.

DTC P1516

The throttle actuator control (TAC) system uses an ignition voltage supply separate from the engine control module (ECM) supply. If the ECM detects a voltage difference between the two circuits, this DTC will set.

This diagnostic procedure supports the following DTC

DTC P1682 Ignition 1 Switch Circuit 2

1. The ignition is ON.
2. DTC P1682 runs continuously when the above condition is met.

1. The ignition 1 voltage is less than 10 volts.
2. The above condition is present for more than 1.6 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.

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 P1682

The throttle actuator control (TAC) system uses 2 accelerator pedal position (APP) sensors to monitor the pedal position. Two processors are also used to monitor the TAC system data. The engine control module (ECM) performs an intrusive test in order to detect that the APP signals are not shorted together. The ECM accomplishes this by pulling the APP sensor 2 low momentarily and looking for sensor 1 to also be low. The TAC system also performs this test on the throttle position (TP) sensors. This diagnostic monitors the transistor used to pull one pedal and one throttle sensor to ground simultaneously. Additionally, both processors monitor each other's data to verify that the indicated APP calculation is correct.

If the transistor does not toggle within a calibrated period, or the indicated APP calculation is incorrect, DTC P1680 sets

1. The system voltage is more than 5.23 volts.
2. The ignition is in Unlock/Accessory or Run position.
3. DTCs P0601, P0602, P0604, P0606, P0607 or P1621 are not set.

1. The APP sensor 2 voltage is more than 1.75 volts for more than 0.3 second during the intrusive test.
2. The APP sensor calculations in the main processor differ from the motor control processor by more than 0.142 volt.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The control module turns OFF the malfunction indicator lamp (MIL) after 3 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 numbers below refer to the step numbers on the diagnostic table.

1. 2: A DTC P0602 indicates that the ECM is not programmed.

1. 5: Resistance is measured at the pedal assembly because a pedal resistance that is lower than the specified value will set this DTC

DTC P1680

The transmission control module (TCM) uses the controller area network (CAN) to communicate with the engine control module (ECM). If the ECM detects that the TCM has set a non-emission related transmission code and is requesting the service vehicle soon (SVS) message on the driver information center (DIC), DTC P1700 sets.

1. The ignition is ON.
2. The TCM has determined that a non-emissions related malfunction exists.

The ECM is requesting an SVS message on the DIC.

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.

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 P1700

The commanded throttle position (TP) is compared to the actual TP based on the accelerator pedal position (APP) and possibly other limiting factors. Both values should be within a calibrated range of each other. The engine control module (ECM) continuously monitors the commanded and actual throttle positions. This DTC sets if the values are greater than the calibrated range.

This diagnostic procedure supports the following DTC

DTC P2101 Throttle Actuator Position Performance

1. The ignition is ON.
2. The ignition voltage is greater than 8 volts.
3. The system is not in Battery Saver mode.
4. The engine is running.
5. DTC P0068 is not set.
6. DTC P2101 runs continuously when the above conditions are met.

1. The difference between the predicted and the actual TP is more than a calibrated amount.
2. The above condition is present for more than 0.6 second.

1. The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
2. The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
3. The control module commands the TAC system to operate in the Reduced Engine Power mode.
4. A message center or an indicator displays Reduced Engine Power.
5. Under certain conditions the control module commands the engine OFF.

1. The ECM turns OFF the MIL after 3 consecutive drive trips that the diagnostic runs and passes.
2. A History DTC clears after 40 consecutive warm-up cycles in which there are no failures reported of this diagnostic or any other emission related diagnostic.
3. The scan tool clears the MIL/DTC.

1. The throttle valve is spring loaded to a slightly open position. This is referred to as the rest position.
2. The throttle valve should not be completely closed nor should they be open any more than the specified amount.
3. The throttle valve should move open and to the closed position without binding under the normal spring pressure.
4. The throttle should NOT be free to move open or closed WITHOUT spring pressure.
5. Replace the throttle body if any of these conditions are found.

1. The scan tool has the ability to operate the throttle control system using Special Functions. Actuate the throttle valve using the throttle blade control function located in the Throttle Actuator Control (TAC) System menu. This function will operate the throttle valve through the entire range in order to determine if the throttle body and system operate correctly.
2. Inspect for the following conditions: Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. Poor connections at the ECM or at the component-Inspect the harness connectors for a poor terminal to wire connection. Refer to «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cobalt/i-2004-2010/remont/electrical-component-locations/#wiring-systems-electrical-power-management__testing-for-intermittent-conditions-and-poor) in Wiring Systems for the proper procedure. For an intermittent condition, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-22l-troubleshooting-diagnosis__intermittent-conditions) .

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

1. 8: The throttle valve is spring loaded in a slightly open position and should move in either direction without binding. The throttle valve should always be under spring pressure.
2. 11: When the ignition is turned ON, the ECM operates the throttle control motor to verify the integrity of the system prior to start-up. This can be seen by the momentary flash of the test lamp as the ignition is turned ON.

DTC P2101

See also:
• Evaporative Emission (EVAP) Canister Filter Replacement
• Evaporative Emissions (EVAP) Hose Routing Diagram
• Diagnostic System Check - Vehicle
• Testing for Intermittent Conditions and Poor Connections
• Connector Repairs
• Circuit Testing
• Wiring Repairs
• Diagnostic Trouble Code (DTC) List - Vehicle
• Engine Controls Connector End Views
• Engine Control Module (ECM) Connector End Views
• Intermittent Conditions
• Control Module References
• Lifting and Jacking the Vehicle
• Service Programming System (SPS)
• Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement
• Instrument Panel Cluster (IPC) Replacement
• Checking Aftermarket Accessories
• Inducing Intermittent Fault Conditions
• Temperature vs Resistance
• Restricted Exhaust
• Altitude vs Barometric Pressure
• DTC P0106
• DTC P2135
• Probing Electrical Connectors
• Measuring Voltage Drop
• Scan Tool Data List
• Silicon Contamination of Heated Oxygen Sensors Notice
• Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool)
• Oil Consumption Diagnosis
• Loss of Coolant
• DTC P0641