GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Enclave - AWD 🢒 DTC 🢒 DTC P0455 or P0497

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0455:  Evaporative Emission (EVAP) System Large Leak Detected

DTC P0497:  Evaporative Emission (EVAP) System No Flow During Purge

Circuit/System Description

The control module tests the evaporative emission (EVAP) system for a large leak, or a stuck closed EVAP canister purge valve. 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 valve OPEN and the EVAP vent 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 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 increases too slowly, a DTC sets.

FTP Sensor Signal Voltage

Fuel Tank Pressure

High, Approximately 1.5 Volts or More

Negative Pressure/Vacuum

Low, Approximately 1.5 Volts or Less

Positive Pressure

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 valves.

Control Module Command

EVAP Canister Purge Valve

EVAP Canister Vent Valve

ON

Open

Closed

OFF

Closed

Open

Conditions for Running the DTC
    • Before the engine control module (ECM) can report DTC P0455 or DTC P0497 failed, DTCs P0443, P0450, P0451, P0452, P0453, P0458, and P0459 must run and pass.
    • DTC P0100, P0101, P0102, P0103, P0111, P0112, P0113, P0116, P0117, P0118, P0119, P0443, P0446, P0449, P0450, P0451, P0452, P0453, P0458, P0459, P0496, P0498, P0499, P0560, P0562, P0563, P0700, P2122, P2123, P2127, P2128, P2138, P2227, P2228, or P2229 is not set.
    • The ignition voltage is between 10-18 volts.
    • The engine run time is greater than 10 minutes.
    • The FTP is between -18.7 and +9.8 mm Hg (-10.0 and +5.2 in. H2O).
    • The Closed Loop fuel control is enabled.
    • The long term fuel trim remains steady, less than 3 percent change in 200 ms over a period of 8 seconds.
    • The engine is idling.
    • The barometric pressure (BARO) is greater than 68 kPa.
    • The fuel level is between 11-88 percent.
    • The ambient air temperature (IAT) is between 2-32°C (36-90°F).
    • The engine coolant temperature (ECT) is within 10°C (18°F) of the ambient air temperature at engine start.
    • The vehicle speed sensor (VSS) is less than 3 km/h (2 mph).
    • The above conditions are met for greater than 30 seconds.
    • DTC P0455 or DTC P0497 will attempt to run up to 10 times or until the test completes successfully once per ignition cycle.

Conditions for Setting the DTC
    • The ECM detects the EVAP system is not able to achieve or maintain vacuum during the diagnostic test.
    • The condition exists for greater than 4 seconds or for a cumulative of 30 seconds.

Action Taken When the DTC Sets

DTC P0455, DTC P0497 is a Type A/B DTC.

Conditions for Clearing the DTC

DTC P0455, DTC P0497 is a Type A/B DTC.

Diagnostic Aids
    • A loose, missing, or damaged fuel fill cap can cause this DTC to set.
    • A stuck closed, blocked, or restricted EVAP canister purge solenoid valve, can cause this DTC to set.
    • A blockage or restriction in the EVAP canister purge solenoid valve vacuum supply hose, EVAP canister purge solenoid valve purge pipe, EVAP canister, or vapor pipe, can cause this DTC to set.
    • 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.
    • To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) 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.
    • To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .
    • Observe the Freeze Frame/Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition occurs that caused the DTC to set. This may assist in diagnosing the condition.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Evaporative Emission Control System Description

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

    • J 41413-SPT High Intensity White Light
    • J 41413-VLV EVAP Port Vent Fitting Tool
    • J 41413-200 Evaporative Emissions System Tester (EEST)
    • J 41413-300 EVAP Cap and Plug Kit
    •  CH-48096 EVAP Service Port Access Tool
    • GE-41415-50 Fuel Tank Cap Adapter

Circuit/System Verification
  1. Verify the following conditions do not exist in the EVAP system:
    2. • Loose, incorrect, missing, or damaged fuel fill cap
    • Loose, missing, or damaged service port schrader valve, if equipped
    • A damaged EVAP canister purge solenoid valve
    • Disconnected, incorrectly routed, kinked, or damaged EVAP pipes and hoses
    • A damaged EVAP vent valve or EVAP canister
         ⇒If you find any of the above conditions, repair as necessary.

    Note: Refer to the J 41413-200 operation manual for detailed instructions.

  2. Remove the fuel fill cap. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50 .
  3. Calibrate the J 41413-200 Flow Meter to the correct leak orifice for the vehicle.
  4. Command the EVAP vent solenoid valve closed with a scan tool.

    5. Note: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.

  5. Activate the J 41413-200 and compare the flow meter's stable floating indicator position to the red flag. The floating indicator should be level with the red flag.
    6. ⇒If the floating indicator is above the red flag, test for a leak in the EVAP system.
    ⇒If the floating indicator is below the red flag, test for a blockage or restriction in the EVAP system.
  6. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Leak Testing

    Note: 

       • You must start with the Circuit/System Verification before proceeding with Circuit/System Testing.
       • Ensure that the vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. The system flow will be less with higher temperatures.

  1. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50 .
  2. Connect the CH-48096 between the EVAP purge solenoid and the EVAP purge pipe.
  3. Turn the nitrogen/smoke valve on the control panel to SMOKE.
  4. Command the EVAP vent solenoid closed with a scan tool.
  5. Use the remote switch to introduce smoke into the EVAP system.
  6. Use the J 41413-VLV to open the EVAP service port. Once smoke is observed, remove the J 41413-VLV .

    7. Note: Introduce smoke at 15 second intervals while testing the system.

  7. Verify that smoke is not exiting the entire EVAP system with the J 41413-SPT .

    8. Note: The fuel tank may need to be lowered to improve visibility of some of the EVAP system components.

    ⇒If smoke is observed, repair the condition as necessary.
  8. Remove the J 41413-200 nitrogen supply hose from the GE-41415-50 , and remove the GE-41415-50 from the filler neck.
  9. Install the fuel fill cap.
  10. Connect the J 41413-200 nitrogen/smoke supply hose to the EVAP service port of the CH-48096 .
  11. Command the EVAP vent solenoid closed with a scan tool.
  12. Use the remote switch to introduce smoke into the EVAP system.

    13. Note: The fuel tank may need to be lowered to improve visibility of some of the EVAP system components.

  13. Verify that smoke is not exiting the entire EVAP system with the J 41413-SPT .
    14. ⇒If smoke is observed, repair the condition as necessary.
  14. Verify individual EVAP system components do not leak using the J 41413-300 .
    15. ⇒If a condition is found replace the affected component.

Blockage/Restriction Testing

  1. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50 .
  2. Seal the EVAP system using the EVAP Purge/Seal function with a scan tool.
  3. Pressurize the EVAP system with nitrogen to 9.33 mm/Hg (5 in/H2O). Compare the scan tool Fuel Tank Pressure Sensor parameter to the J 41413-200 pressure/vacuum gage. The FTP sensor parameter should be within 1.86 mm/Hg (1 in/H2O) of the pressure/vacuum gage.
    4. ⇒If not within the specified range, replace the FTP sensor.
  4. Command the EVAP purge solenoid to 100 percent with a scan tool. The scan tool FTP sensor parameter should drop to less than 1.86 mm/Hg (1 in/H2O).
    5. ⇒If greater than the specified value, disconnect the EVAP pipes listed below one at a time while observing the scan tool FTP sensor parameter. If the FTP sensor parameter drops to less than the specified when a pipe is disconnected, repair the blockage or restriction in one of the following EVAP pipe/hoses:
    • EVAP purge vacuum source from the EVAP purge solenoid
    • EVAP purge pipe from the EVAP purge solenoid
    • EVAP purge pipe at the EVAP canister
    • EVAP vapor pipe at the EVAP canister
  5. If a condition with the EVAP system cannot be located, refer to Diagnostic Aids for additional information.

Component Testing
  1. Seal the EVAP system using the EVAP Purge/Seal function with a scan tool.
  2. Pressurize the EVAP system to 9.33 mm/Hg (5 in/H2O).
  3. Compare the scan tool Fuel Tank Pressure sensor parameter to the J 41413-200 pressure/vacuum gage. Verify the scan tool FTP sensor parameter is within 1.86 mm/Hg (1 in/H2O) of the pressure/vacuum gage.
    4. ⇒If not within the specified range, replace the FTP sensor.
  4. Command the EVAP vent valve open with a scan tool. Verify the scan tool Fuel Tank Pressure parameter is at 0 mm/Hg (0 in/H2O).
    5. ⇒If not within the specified range, replace the FTP sensor.

Repair Instructions
    •  Fuel Tank Pressure Sensor Replacement
    •  Evaporative Emission Canister Purge Solenoid Valve Replacement
    •  Evaporative Emission Canister Vent Solenoid Valve Replacement
    •  Evaporative Emission Hoses/Pipes Replacement - Chassis/Canister
    •  Evaporative Emission Canister Replacement

Repair Verification
  1. Turn the nitrogen/smoke valve to nitrogen.
  2. Command the EVAP vent valve closed with a scan tool.
  3. Use the remote switch to activate the J 41413-200 .
  4. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating indicator stabilizes.
  5. Verify the flow meter's stable floating indicator position is at or below the red flag.
  6. Remove the CH-48096 , and connect the purge line to the EVAP purge solenoid.
  7. Clear the DTCs with a scan tool.