Engine Controls - 2.0l (DTC p0341 to p1516) Chevrolet Cobalt I

Circuit Description

The camshaft position (CMP) sensor is triggered by a notched reluctor wheel built onto the exhaust camshaft sprocket. The CMP sensor provides four signal pulses every camshaft revolution. Each notch, or feature of the reluctor wheel is of a different size which is used to identify the compression stroke of each cylinder and to enable sequential fuel injection. The CMP sensor is connected to the powertrain control module (PCM) by the following circuits

1. A 12-volt circuit
2. A low reference circuit
3. A signal circuit

The PCM monitors the CMP sensor performance by comparing the number of it's pulses to the CKP sensor pulses. There is a given number of CMP sensor pulses to CKP sensor pulses. If this ratio is not kept, the PCM will set DTC P0341.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P0341 Camshaft Position (CMP) Sensor Performance

Conditions for Running the DTC

1. DTCs P0106, P0107, P0108, and P0340 are not set.
2. The engine is running.
3. The manifold absolute pressure (MAP) is more than 45 kPa.
4. This DTC runs continuously.

Conditions for Setting the DTC

The ECM detects more than 120 extra CMP signal pulses or less than 80 CMP pulses than expected when compared to the CKP sensor signal pulses.

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 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 P0341

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

1. An ignition voltage circuit
2. A ground
3. An IC circuit

If the PCM detects an improper voltage level on the IC circuit of the ignition coil/module, it will set the following corresponding DTCs

1. DTC P0351 for ignition coil/module 1
2. DTC P0352 for ignition coil/module 2
3. DTC P0353 for ignition coil/module 3
4. DTC P0354 for ignition coil/module 4

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC P0351 Ignition Coil 1 Control Circuit
2. DTC P0352 Ignition Coil 2 Control Circuit
3. DTC P0353 Ignition Coil 3 Control Circuit
4. DTC P0354 Ignition Coil 4 Control Circuit

1. The engine is running.
2. DTC P0351-P0354 runs continuously once the above conditions are met.

The PCM detects one of the following failures on the IC circuit of the ignition coil/module for less than 1 second.

1. An open
2. A short to ground
3. A short to voltage

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 P0351-P0354

A three-way catalytic converter (TWC) controls emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The catalyst within the converter promotes a chemical reaction which oxidizes the HC and the CO that are present in the exhaust gas. This process converts the HC and the CO into water vapor and carbon dioxide (CO2), and reduces the NOx, converting the NOx into nitrogen. The catalytic converter also stores oxygen. The powertrain control module (PCM) monitors this process by using a heated oxygen sensor (HO2S) that is in the exhaust stream after the TWC. This HO2S 2, also referred to as the catalyst monitor sensor, produces an output signal that the PCM uses to calculate the oxygen storage capacity of the catalyst. This indicates the ability of the catalyst to convert the exhaust emissions efficiently. The PCM monitors the efficiency of the catalyst by allowing the catalyst to heat, then wait for a stabilization period while the engine is idling. The PCM then adds and removes fuel while monitoring the HO2S 2. When the catalyst is functioning properly, the HO2S 2 response to the extra fuel is slow compared to the response of the HO2S 1, which is located before the TWC. When the HO2S 2 response is near that of the HO2S 1, the oxygen storage capability and efficiency of the catalyst may be degraded below an acceptable threshold. If the PCM detects the degraded condition, DTC P0420 sets.

This diagnostic procedure supports the following DTC

DTC P0420 Catalyst System Low Efficiency

1. DTCs P0030, P0036, P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0171, P0172, P0220, P0300, P0315, P0335, P0336, P0340, P0341, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P0502, P0503, P0506, P0507, P1133, P1516, P1681, P2135, P2176 are not set.
2. The engine has been running for more than 10 minutes.
3. The engine speed is within 200 RPM of the desired idle.
4. The engine coolant temperature (ECT) is between 50-125°C (122-257°F).
5. The barometric pressure (BARO) is more than 70 kPa.
6. The TWC calculated temperature is between 550-765°C (1,022-1,409°F).
7. The vehicle is in Closed Loop.
8. The intake air temperature (IAT) is between -20 and +80°C (-4 and +176°F).
9. The battery voltage is more than 9 volts.
10. The throttle position (TP) is 1.5 percent or less.
11. The short term fuel trim (FT) is between -10 and +10 percent.
12. The engine load must be stable.
13. Idle the engine and keep the vehicle in Drive, or depress the clutch pedal for a manual transmission vehicle, to activate the diagnostic. Within 60 seconds the air fuel ratio will transition lean, above 15.3, for up to 7 seconds, and then may transition rich, below 14.1, for up to 7 seconds.
14. Verify if DTC P0420 has passed or failed this ignition cycle with the scan tool.
15. This diagnostic attempts 1 test during each valid idle period, once the above conditions have been met for 1 minute. This diagnostic attempts up to 6 tests during each drive cycle.

1. The PCM determines that the efficiency of the catalyst has degraded below a calibrated threshold.
2. This diagnostic may conclude in as few as one test attempt. However, this diagnostic may require as many as 18 test attempts, which would require at least 3 drive cycles. Each test attempt concludes within approximately 7 minutes.
3. The PCM determines that the efficiency of the catalyst has degraded below a calibrated threshold.

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.

Diagnostic Aids

1. These conditions may cause a catalytic converter to degrade. Inspect for the following conditions: An engine misfire High engine oil or high coolant consumption Retarded spark timing A weak or poor spark A lean fuel mixture A rich fuel mixture A damaged oxygen sensor or wiring harness The catalyst test may abort if the vehicle falls outside the conditions for running the DTC. The catalyst test may abort due to a change in engine load such as the A/C or engine cooling fan cycling. A catalyst may be temporarily degraded if a fuel with high sulfur content has been used. Drive the vehicle at highway speeds for 10 minutes and retest the converter. If 6 tests have been attempted and the DTC has not run or passed during this key cycle, turn the key to OFF for 30 seconds. Perform the Conditions for Running a second time. A maximum of 12 tests per key cycle will run if each test is a combination of pass, fail, or abort tests. After a code clear, the catalyst test will run once if the test is a pass. IMPORTANT: DO NOT touch the accelerator, the HVAC, or the steering wheel while a catalyst test is in progress. Allow the engine to return to a stabilized idle. Keep the vehicle in Drive.
2. If an intermittent condition cannot be duplicated, the information included in the Freeze Frame Records can be useful in determining the vehicle operating conditions when the DTC was set.
3. If the condition is determined to be intermittent, 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.

DTC P0420

System Description

This diagnostic tests the evaporative emission (EVAP) system for a small leak when the key is turned OFF and the correct conditions are met.

Heat from the exhaust system is transferred into a vehicle fuel tank while the vehicle is operating. When the vehicle is turned OFF and the EVAP system is sealed, a change in the fuel tank vapor temperature occurs, which results in corresponding pressure changes in the fuel tank vapor space. This change is monitored by the control module using the fuel tank pressure sensor input. The control module then makes a judgement on the integrity of the system. With a 0.51 mm (0.020 in) leak in the system, the amount of pressure change observed is significantly less than that of a sealed system.

If the control module detects a pressure change less than a calibrated amount, DTC P0442 sets.

This diagnostic procedure supports the following DTC

DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

1. DTCs P0095, P0096, P0097, P0098, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0128, P0336, P0443, P0446, P0452, P0453, P0455, P0461, P0462, P0463, P0464, P0496, P0502, P0503, P2610 are not set.
2. The diagnostic runs once after a cold start drive cycle.
3. DTC P0455 must run and pass.
4. The start up intake air temperature (IAT) is between 4-30°C (39-86°F).
5. The start up engine coolant temperature (ECT) is less than 30°C (86°F).
6. The start up IAT and ECT are within 8°C (15°F).
7. The barometric pressure (BARO) is more than 74 kPa.
8. The ambient air temperature is between 2-32°C (36-90°F).
9. The engine run time minimum is 10 minutes.
10. The vehicle has traveled more than 5 km (3.1 mi) this trip.
11. The ECT is more than 70°C (158°F).
12. The fuel level is between 15-85 percent.
13. The ignition is OFF.
14. One test occurs at ignition OFF after a drive cycle and may require up to 45 minutes to complete. No more than 2 tests per day are allowed. To report a fail, 5-12 tests must be completed.

The control module detects a pressure change that is less than a calibrated amount within 45 minutes after ignition OFF when the above conditions have been met.

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.

1. A leak in the EVAP system can be verified by the use of the flow meter on the J 41413-200 Evaporative Emissions System Tester (EEST). See «Special Tools»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction__special-tools) . Refer to J 41413-200 operation manual for flow meter use.
2. To help locate intermittent leaks, use the J 41413-200 to introduce smoke into the EVAP system. See «Special Tools»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction__special-tools) . Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. See «Special Tools»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction__special-tools) .
3. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT . See «Special Tools»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction__special-tools) .
4. A condition may exist where a leak in the EVAP system only exists under a vacuum condition. By using the scan tool Purge/Seal function to create a vacuum, seal the system and observe the FTP parameter for vacuum decay, this type of leak may be detected.
5. For intermittent conditions, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .
6. Introducing smoke in 15-second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.

Test Description

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

1. 5: This step verifies that repairs are complete.

DTC P0442

An ignition voltage is supplied directly to the evaporative emission (EVAP) canister purge solenoid valve. The EVAP canister purge solenoid valve is pulse width modulated (PWM). The scan tool displays the amount of ON time as a percentage. The control module monitors the status of the driver. The control module controls the EVAP canister purge solenoid valve ON time by grounding the control circuit via an internal switch called a driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.

This diagnostic supports the following DTC

DTC P0443 Evaporative Emissions (EVAP) Purge Solenoid Control Circuit

1. The ignition is ON.
2. The system voltage is between 6-18 volts.
3. DTC P0443 runs continuously once the above conditions are met.

1. The control module detects that the commanded state of the driver and the actual state of the control circuit do not match.
2. The above conditions are present for a minimum of 12 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 numbers below refer to the step numbers on the diagnostic table.

1. 2: This step tests if the concern is active. The EVAP canister purge solenoid valve is PWM. You should hear a clicking sound when the EVAP canister purge solenoid valve is commanded to 50 percent. The clicking sound should stop when the EVAP canister purge solenoid valve is commanded to 0 percent. The rate at which the valve cycles should increase when the commanded state is increased, and decrease when the commanded state is decreased.
2. 5: This step verifies that the control module is providing ground to the EVAP canister purge solenoid valve.
3. 6: This step tests if a ground is constantly being applied to the EVAP canister purge solenoid valve.

DTC P0443

This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid valve Open and the EVAP canister vent solenoid valve Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid valve Closed and the EVAP canister vent solenoid valve Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated 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 and vent solenoid valves.

DTC P0446

This diagnostic procedure supports the following DTC

DTC P0446 Evaporative Emissions (EVAP) Vent System Performance

1. DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P0220, P0442, P0443, P0449, P0452, P0453, P0455, and P0502 are not set.
2. The ignition voltage is between 10-18 volts.
3. The barometric pressure (BARO) is more than 74 kPa.
4. The fuel level is between 15-85 percent.
5. The start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F).
6. The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
7. The start-up ECT and IAT are within 8°C (14.4°F) of each other.
8. The purge solenoid valve is enabled.
9. DTC P0446 runs once per trip when the above conditions have been met.

1. The fuel tank vacuum is more than 8 inches H2O for 5 seconds during the 13 minute test. OR
2. The fuel tank vacuum is less than -2.5 inches H2O or more than +5 inches H2O for 3 seconds after a cold start ignition ON.
3. The fuel tank vacuum is greater than a calibrated amount for a calibrated period of time.

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. The EVAP system tests run when the engine is first started and meets the Conditions for Running the DTC. An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP canister vent inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill condition.
2. An EVAP canister, vent hose, or vent solenoid valve that has restricted flow may cause this DTC to set. Using a purge solenoid command with a scan tool will allow vacuum to be applied to the system instead of pressure. With the engine running, the EVAP canister vent solenoid valve open and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than 5 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-20l-introduction) and «Evaporative Emission (EVAP) System Cleaning»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction) .
4. Disconnecting one component at a time while the EVAP system is under flow will help to pinpoint a restriction in the system.
5. 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.
6. For intermittent conditions, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .

DTC P0446

A battery voltage is supplied to the evaporative emission (EVAP) canister vent solenoid valve. The control module grounds the EVAP canister vent solenoid valve control circuit to close the valve by means of an internal switch called a driver. The scan tool displays the commanded state of the EVAP canister vent solenoid valve as ON or OFF. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, 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 vent solenoid valve.

DTC P0449

This diagnostic procedure supports the following DTC

DTC P0449 Evaporative Emission (EVAP) Vent Solenoid Control Circuit

1. The ignition is ON.
2. The system voltage is between 6-18 volts.
3. DTC P0449 runs continuously once the above conditions are met.

1. The control module detects that the commanded state of the driver and the actual state of the control circuit do not match.
2. The above conditions are present for a minimum of 12 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 numbers below refer to the step numbers on the diagnostic table.

1. 2: Listen for a click when the valve operates. Verify that both the ON and the OFF states are commanded.
2. 5: This step verifies that the control module is providing ground to the EVAP canister vent solenoid valve.
3. 6: This step tests if the EVAP canister vent solenoid valve control circuit is grounded.

DTC P0449

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.

This diagnostic procedure supports the following DTC

DTC P0451 Fuel Tank Pressure (FTP) Sensor Performance

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.

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.

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. 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-20l-introduction) .
4. For intermittent conditions, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .
5. Ensure that the reference port on the FTP sensor is unobstructed.

DTC P0451

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 control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the FTP sensor signal voltage goes below a calibrated value, this DTC 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

DTC P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage

1. The ignition is ON.
2. DTC P0452 runs continuously after a 1-second delay.

1. The FTP voltage is less than 0.1 volt.
2. All conditions present for more than 5 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 numbers below refer to the step numbers on the diagnostic table.

1. 3: This step verifies that the condition is present.
2. 5: This step tests the 5-volt reference of the FTP sensor.
3. 6: This step tests if another component is causing the 5-volt reference circuit condition.
4. 7: If the scan tool displays 5 volts, the FTP sensor signal circuit, the FTP sensor 5-volt reference circuit, and the control module are OK.

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 control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the FTP sensor signal voltage increases above a calibrated value, this DTC sets.

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

DTC P0453

This diagnostic supports the following DTC

DTC P0453 Fuel Tank Pressure (FTP) Sensor Circuit High Voltage

1. The ignition is ON.
2. DTC P0453 runs continuously after a 1-second delay.

1. The FTP sensor voltage is more than 4.9 volts.
2. All conditions are present for more than 5 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.

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.

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

1. 2: This step determines if the condition is present.

1. 4: This step tests the signal circuit of the FTP sensor.
2. 5: This step tests the ground circuit of the FTP sensor.
3. 6: This step tests the 5-volt reference circuit of the FTP sensor.

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. See «Special Tools»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction__special-tools) .
3. Ensure that the reference port on the FTP sensor is unobstructed.
4. For intermittent conditions, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .

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 P0068, P0069, P0095, P0096, P0097, P0098, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0220, P0442, P0443, P0449, P0452, P0453, P0496, P0502, P0562, P0563, P0641, P0651, P1133, P1134 are not set.
2. The engine is running.
3. The ignition voltage is between 10-18 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 4-65°C (39-149°F).
7. The start-up intake air temperature (IAT) is between 4-75°C (39-167°F).
8. The start-up ECT and IAT are within 8°C (16°F) of each other.
9. DTC P0455 runs once per cold start drive cycle once the above conditions are met.

The EVAP system is not able to achieve or maintain vacuum during the diagnostic test for up to 13 minutes.

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. To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. See «Special Tools»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction__special-tools) . Move all EVAP components while observing smoke with a 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.
2. 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.
3. To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with a High Intensity White Light.
4. 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.
5. For intermittent conditions, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-troubleshooting-diagnosis__intermittent-conditions) .

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

1. 3: Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
2. 5: This step verifies proper operation of the FTP sensor.
3. 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 Closed and the EVAP canister vent solenoid valve Closed. 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 and vent solenoid valves.

DTC P0496

This diagnostic supports the following DTC

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

1. DTCs P0068, P0069, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0125, P0128, P0220, P0442, P0443, P0449, P0452, P0453, P0455, P0461, P0462, P0463, P0464, P0502, P2135, P2610 are not set.
2. The ignition voltage is between 10-18 volts.
3. The barometric pressure (BARO) is more than 74 kPa.
4. The fuel level is between 15-85 percent.
5. The start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F).
6. The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
7. The start-up ECT and IAT are within 8°C (16°F) of each other.
8. DTC P0496 runs once per drive cycle when the above conditions are met.

The control module detects vacuum during a non-purge condition within 65 seconds of 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 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 P0496

The throttle actuator control (TAC) motor is controlled by the powertrain control module (PCM). The DC motor located in the throttle body drives the throttle plate. In order to decrease idle speed, the PCM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the PCM 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 P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0122, P0123, P0125, P0130, P0171, P0172, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0300, P0336, P0440, P0442, P0446, P0452, P0453, P0502, P0503, P0641, P0651, P1512, P1514, P1516, P2101, P2135 are not set.
2. The engine is operating for at least 2 seconds.
3. The engine coolant temperature (ECT) is more than -40°C (-40°F).
4. The intake air temperature (IAT) is more than -40°C (-40°F).
5. The barometric pressure (BARO) is more than 65 kPa.
6. The system voltage is between 9-18 volts.
7. The vehicle speed is less than 4.8 km/h (3 mph).
8. DTC P0506 runs continuously when the above conditions are met.

1. The actual idle speed is approximately 150 RPM lower than the desired idle speed.
2. The above condition is present for 15 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 RPM, the test determines whether the RPM is too high or too low.

DTC P0506

The throttle actuator control (TAC) motor is controlled by the powertrain control module (PCM). The DC motor located in the throttle body drives the throttle plate. In order to decrease idle speed, the PCM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the PCM 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 P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0122, P0123, P0125, P0130, P0171, P0172, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0300, P0336, P0442, P0446, P0452, P0453, P0455, P0502, P0503, P0641, P0651, P1514, P1516, P2101, P2135, P2176 are not set.
2. The engine is operating for at least 2 seconds.
3. The engine coolant temperature (ECT) is more than -40°C (-40°F).
4. The intake air temperature (IAT) is more than -40°C (-40°F).
5. The barometric pressure (BARO) is more than 65 kPa.
6. The system voltage is between 9-18 volts.
7. The vehicle speed is less than 4.8 km/h (3 mph).
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 10 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 powertrain control module (PCM). This diagnostic also addresses if the PCM is not programmed.

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 P0604 Control Module Random Access Memory (RAM)
5. DTC P0606 Control Module Internal Performance
6. DTC P0607 Control Module Performance
7. DTC P1681 Control Module Throttle Position (TP) System Performance

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

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

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

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

1. The A/C pressure sensor
2. The throttle position (TP) sensor 1
3. The accelerator pedal position (APP) sensor 2
4. The fuel tank pressure (FTP) sensor
5. The supercharge inlet pressure (SCIP) sensor
6. The barometric pressure (BARO) sensor
7. The camshaft position (CMP) sensor

The PCM monitors the voltage on the 5-volt reference circuit. If the voltage is out of tolerance, the PCM 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, and P2610 are not set.
2. The ignition is in unlock, accessory, run, or crank mode.
3. The ignition voltage is greater than 5.2 volts.
4. DTC P0641 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 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 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

1. The engine is running.
2. DTC P0650 runs continuously when the above condition is met.

The control module detects that the commanded state of the MIL driver and the actual state of the control circuit do not match for 12 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 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 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 powertrain control module (PCM) uses the 5-volt reference circuit as a sensor feed to the following sensors

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

The PCM monitors the voltage on the 5-volt reference circuit. If the voltage is out of tolerance, the PCM 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, and P2610 are not set.
2. The ignition is in unlock, accessory, run, or crank mode.
3. The ignition voltage is greater than 5.2 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 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 P0651

The intake airflow system performance diagnostic provides the within-range rationality check for the mass air flow (MAF), supercharger inlet pressure (SCIP), and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing 3 separate models for the intake system.

1. One model, the throttle model, describes the flow through the throttle body and is used to estimate the MAF through the throttle body as a function of barometric pressure (BARO), throttle position, intake air temperature (IAT), and estimated SCIP.
2. Another model, the first intake manifold model, describes the intake manifold and is used to estimate SCIP as a function of the MAF into the intake manifold from the throttle body and the MAF out of the intake manifold caused by engine pumping. The flow into the intake manifold from the throttle uses the MAF estimate calculated from the above throttle model.
3. Another model is the second intake manifold model and 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. Finally, 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, SCIP, and TP that are obtained from this system of models and calculations are then compared to the actual measured values from the MAF, SCIP, 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 powertrain control module (PCM) detects that the actual measured airflow from MAF, SCIP, 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, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0335, P0336, P1183, P1184, P2228, P2229 are not set.
2. The engine speed is between 400-6,400 RPM.
3. The IAT Sensor 1 parameter is between -7°C and +125°C (+19 and +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 PCM detects that the actual measured airflow from the MAF, SCIP, 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, SCIP, and TP sensors to be shifted in value at the same time will cause this DTC to set.
2. A wide open throttle (WOT) 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 180 g/s or more at the time of the 2-3 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
3. A skewed or stuck engine coolant temperature (ECT) or IAT sensor 1 will cause the calculated models to be inaccurate and may cause this DTC to run when it should not.
4. A skewed MAP sensor may cause this DTC to set.
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 gs, 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 PCM to calculate the airflow models is initially based on the BARO sensor at key ON. With the ignition ON and the engine OFF, the BARO 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. Refer to «Altitude vs Barometric Pressure»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-introduction__altitude-vs-barometric-pressure) .
7. 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-20l-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. 7: The SC Inlet Pressure parameter is the difference between BARO and SCIP, and at KOEO should be close to zero.
3. 14: This voltage drop test will determine if high resistance has caused this DTC to set.
4. 16: This step verifies the voltage signal from the PCM to the MAF sensor connector.
5. 17: This step will determine if the MAF sensor is able to generate a frequency signal.
6. 18: This step will determine if an abnormal resistance or a short to the IAT signal circuit has skewed the MAF sensor frequency signal.

DTC P1101

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 powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperatures 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 PCM monitors the number of rich-to-lean and lean-to-rich transitions. If the PCM 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 P0030, P0036, P0068, P0069, P0097, P0098, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121, P0131, P0132, P0134, P0135, P0141, P0201, P0202, P0203, P0204, P0220, P0300, P0442, P0443, P0446, P0449, P0452, P0453, P0461, P0496, P1516, P1681, P2101, P2135, or P2176 are not set.
2. The catalyst test is not active.
3. The ECT Sensor parameter is more than 70°C (158°F).
4. The Engine Speed parameter is between 1,000-3,500 RPM.
5. The Ignition 1 Signal parameter is between 11-18 volts.
6. The Engine Run Time parameter is more than 200 seconds.
7. The Loop Status parameter is closed.
8. The TP Indicated Angle parameter is equal to or more than 5 percent.
9. The Fuel Level Sensor parameter is more than 10 percent.
10. The MAF Sensor parameter is between 15-50 g/s.
11. DTC P1133 runs continuously when the above conditions are met for 2 seconds.

1. The PCM detects that the HO2S 1 rich-to-lean counts, or the lean-to-rich counts is less than a calibrated value.
2. DTC 1133 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.

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

1. 2: If the voltage is varying above and below the specified value, the condition is not present.

DTC P1133

The intake air flow system performance diagnostic provides the within-range rationality test for the mass air flow (MAF), the supercharger inlet pressure (SCIP), and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing four 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), throttle position, intake air temperature (IAT), and estimated SCIP.
2. The first intake manifold model describes the intake manifold and is used to estimate SCIP as a function of the MAF into the intake manifold from the throttle body and the MAF out of the intake manifold caused by engine pumping. The flow into the intake manifold from the throttle uses the MAF estimate calculated from the 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 the MAF, the SCIP, and the TP that are obtained from this system of models and calculations are then compared to the actual measured values from the MAF, the SCIP, 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 P1182

If the powertrain control module (PCM) detects that the actual measured air pressure from the SCIP sensor is not within range of the calculated air pressure for the SCIP sensor that is derived from the system of models, DTC P1182 sets.

This diagnostic procedure supports the following DTC

DTC P1182 Supercharger Inlet Pressure (SCIP) Sensor Performance

1. DTCs P0120, P0121, P0220, P0506, P0507, P2135 are not set.
2. The engine speed is between 400-6,400 RPM.
3. The engine coolant temperature (ECT) is between 70-125°C (158-257°F).
4. The IAT is between -7 to +125°C (+19 to +257°F).
5. The change in the TP is less than 5 percent.
6. The above enabling criteria must be stable for more than 5 seconds.
7. DTC P1182 runs continuously when the above conditions are met.

The PCM detects that the actual measured air pressure from the SCIP sensor is not within range of the calculated air pressure for the SCIP sensor that is derived from the system of models by more than 20 kPa 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.

DTC P1182

The supercharger inlet pressure (SCIP) sensor measures both the atmospheric pressure and the vacuum that exists, under different operating conditions, in the supercharger intake plenum. The plenum volume between the throttle body and the supercharger is where this sensor is located, and for the purpose of this diagnostic, this area is considered to be the intake manifold.

The SCIP sensor has the following types of circuits

1. A powertrain control module (PCM) supplied and regulated 5-volt reference circuit
2. A PCM supplied ground for the low reference circuit
3. A sensor signal circuit that supplies a voltage input to the PCM

The diaphragm within the SCIP sensor responds to the pressure changes in the intake manifold, and provides a signal voltage to the PCM on the signal circuit, relative to those pressure changes.

The PCM monitors the SCIP sensor signal for voltage that is outside of the normal range of a properly operating sensor. If the PCM detects a SCIP sensor signal voltage that is excessively low, DTC P1183 sets.

This diagnostic procedure supports the following DTC

DTC P1183 Supercharger Inlet Pressure (SCIP) Sensor Circuit Low Voltage

1. DTCs P0120, P0121, P0220, P2135 are not set.
2. The ignition is ON, or the engine is running.
3. The ignition is ON. OR
4. The TP Indicated Angle parameter is more than 0 percent, when the engine speed is less than 1100 RPM. OR
5. The TP Indicated Angle parameter is more than 10 percent, when the engine speed is more than 1100 RPM.
6. DTC P1183 runs continuously when the above conditions are met.

The PCM detects that the SCIP sensor signal voltage is less than 0.2 volts for more than 2 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: The SCIP sensor 5-volt reference circuit is shared with other sensors. If DTC P0641 is set, this indicates a shorted 5-volt reference circuit, or a shorted component, and should be diagnosed first.

DTC P1183

The supercharger inlet pressure (SCIP) sensor measures both the atmospheric pressure and the vacuum that exists, under different operating conditions, in the supercharger intake plenum. The plenum volume between the throttle body and the supercharger is where this sensor is located, and for the purpose of this diagnostic, this area is considered to be the intake manifold.

The SCIP sensor has the following types of circuits

1. A powertrain control module (PCM) supplied and regulated 5-volt reference circuit
2. A PCM supplied ground for the low reference circuit
3. A sensor signal circuit that supplies a voltage input to the PCM

The diaphragm within the SCIP sensor responds to the pressure changes in the intake manifold, and provides a signal voltage to the PCM on the signal circuit, relative to those pressure changes.

The PCM monitors the SCIP sensor signal for voltage that is outside of the normal range of a properly operating sensor. If the PCM detects a SCIP sensor signal voltage that is excessively high, DTC P1184 sets.

This diagnostic procedure supports the following DTC

DTC P1184 Supercharger Inlet Pressure (SCIP) Sensor Circuit High Voltage

1. DTCs P0120, P0121, P0220, P2135 are not set.
2. The engine has been running for a calibrated length of time that is determined by the start-up engine coolant temperature (ECT). The length of time ranges from 2 minutes at less than -30°C (-22°F) to 1 second at more than 30°C (86°F).
3. The TP Indicated Angle parameter is less than 90 percent when the engine speed is less than 1000 RPM. OR
4. The TP Indicated Angle parameter is less than 98 percent when the engine speed is more than 1000 RPM.

The PCM detects that the SCIP signal voltage is more than 2.4 volts for more than 2 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: The SCIP sensor 5-volt reference circuit is shared with other sensors. If DTC P0641 is set, this indicates a shorted 5-volt reference circuit or a shorted component and should be diagnosed first.

DTC P1184

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 powertrain control module (PCM) 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.

The difference between the predicted and the actual throttle position is more than a calibrated amount 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 PCM 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.
2. The throttle valve should be open approximately 20 percent. This is referred to as the rest position.
3. The throttle valve should not be completely closed nor should they be open any more than the specified amount.
4. The throttle valve should move open and to the closed position without binding under the normal spring pressure.
5. The throttle should NOT be free to move open or closed WITHOUT spring pressure.
6. Replace the throttle body if any of these conditions are found.
7. 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.
8. Inspect for the following conditions: Use the J 35616 Connector Test Adapter Kit for any test that requires probing the PCM harness connector or a component harness connector. Poor connections at the PCM 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. If the condition is intermittent, refer to «Intermittent Conditions»(/chevrolet/cobalt/i-2004-2010/remont/testing-diagnostics/#engine-controls-20l-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 PCM 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

See also:
• Engine Controls Schematics
• Engine Controls Connector End Views
• Powertrain Control Module (PCM) Connector End Views
• Diagnostic System Check - Vehicle
• Intermittent Conditions
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Connector Repairs
• Crankshaft and Bearings Cleaning and Inspection
• Diagnostic Trouble Code (DTC) List - Vehicle
• Circuit Testing
• Control Module References
• Restricted Exhaust
• Exhaust Leakage
• Heated Oxygen Sensor (HO2S) Resistance Learn Reset Notice
• Road Test Caution
• Three-Way Catalytic Converter Damage Notice
• Special Tools
• Testing for Short to Ground
• Troubleshooting with a Test Lamp
• Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement
• Probing Electrical Connectors
• Fuel Tank Pressure Sensor Replacement
• Lifting and Jacking the Vehicle
• Altitude vs Barometric Pressure
• Service Programming System (SPS)
• Instrument Panel Cluster (IPC) Replacement
• Temperature vs Resistance
• DTC P0069
• DTC P2135
• Measuring Voltage Drop
• Using Connector Test Adapters
• Measuring Frequency
• Scan Tool Data List
• Silicon Contamination of Heated Oxygen Sensors Notice
• Alcohol/Contaminants-in-Fuel Diagnosis (w/o Special Tool)
• Oil Consumption Diagnosis
• Loss of Coolant
• DTC P1182