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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 LaCrosse 🢒 Restraints 🢒 SIR 🢒 DTC P0455

DTC Descriptor

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

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

System Description

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 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, 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 valves.

Control Module Command

EVAP Canister Purge Valve

EVAP Canister Vent Valve

ON

Open

Closed

OFF

Closed

Open

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

Conditions for Running the DTC
    • Before the engine control module (ECM) can report DTC P0455 failed, DTC P0443, P0451, P0458, and P0459 must run and pass.
    • DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0221, P0222, P0223, P0446, P0449, P0452, P0453, P0496, P0498, P0499, P0506, P0507, P0560, P0562, P0563, P0700, P2122, P2123, P2127, P2128, and P2138 are not set.
    • The ignition 1 voltage is between 10.5-18 volts.
    • The fuel system is operating in closed loop.
    • The engine is idling.
    • The ambient air temperature is between 2-32°C (36-90°F).
    • The start-up engine coolant temperature (ECT) is within 10°C (18°F) of ambient air temperature.
    • The FTP is between -18.7 to +7.5 mm Hg (-10.0 to +4.0 in H2O).
    • The volumetric efficiency is less than 35 percent.
    • The barometric pressure (BARO) is more than 68 kPa.
    • The fuel level is between 10-92 percent.
    • The vehicle speed sensor (VSS) is less than 2 km/h (3 mph).
    • The engine is operating for more than 16 minutes or the long term fuel is stable.
    • The above conditions are met for more than 11 seconds.
    • DTC P0455 runs once an ignition cycle. The ECM will attempt to run this diagnostic up to 10 times an 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 more than 4 seconds.

Action Taken When the DTC Sets

DTC P0455 is a Type A/B DTC.

Conditions for Clearing the DTC

DTC P0455 is a Type A/B DTC.

Diagnostic Aids
    • A fuel fill cap that is left OFF after a fuel fill, will cause this DTC to set.
    • A loose, missing, or damaged fuel fill cap can cause this DTC to set.
    • A blockage or restriction in the EVAP purge solenoid, purge pipe EVAP canister, or vapor pipe, can cause this DTC to set.
    • A temporary blockage in the EVAP purge solenoid, 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 High Intensity White Light.
    • 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

DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Special Tools Required

    • 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
    • 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
    • A damaged EVAP purge solenoid
    • 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.

    Important: Refer to the J 41413-200 Evaporative Emissions System Tester (EEST) 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. Disconnect the EVAP vent line from the vent solenoid, and seal it, using a suitable plug or a plug from the J 41413-300 .

    5. Important: 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 below 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. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing

Leak Testing

    Important: 

       • 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. Turn the nitrogen/smoke valve on the control panel to SMOKE.
  2. Disconnect the EVAP vent line from the vent solenoid, and seal it, using a suitable plug or a plug from the J 41413-300 .
  3. Use the remote switch to introduce smoke into the EVAP system.
  4. Use the J 41413-VLV to open the EVAP service port. Once smoke is observed, remove the tool.

    5. Important: Introduce smoke at 15 second intervals while testing the system.

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

    6. Important: 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.
  6. Verify the EVAP system using the EVAP service port. Connect the J 41413-200 nitrogen/smoke supply hose to the EVAP service port.
  7. Use the remote switch to introduce smoke into the EVAP system.
  8. Verify that smoke is not exiting the entire EVAP system with the J 41413-SPT .

    9. Important: 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.
  9. Verify the individual EVAP system components for a leak using the J 41413-300 . The EVAP system components should not leak.
    10. ⇒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. Disconnect the EVAP vent line from the vent solenoid, and seal it, using a suitable plug or a plug from the J 41413-300 .
  3. Pressurize the EVAP system with nitrogen to 5 inches H20. Compare the fuel tank pressure sensor parameter with a scan tool to the J 41413-200 pressure/vacuum gage. The scan tool FTP sensor parameter should be within 1 inch H20 of the pressure/vacuum gage.
    4. ⇒If the FTP sensor parameter is not within 1 inch H20 of the pressure/vacuum gage, replace the FTP sensor.
  4. Increase the EVAP purge solenoid to 100 percent. The FTP sensor pressure should drop to less than 1 in H2O.
    5. ⇒If the FTP sensor parameter is greater than 1 in H2O, disconnect the EVAP pipes listed below one at a time while observing the FTP sensor parameter with a scan tool. If the FTP sensor parameter drops to less than 1 in H2O when a pipe is disconnected, repair the blockage or restriction in the one of the following EVAP pipe/hoses:
    4.1. EVAP purge vacuum source from the EVAP purge solenoid
    4.2. EVAP purge pipe from the EVAP purge solenoid
    4.3. EVAP purge pipe at the EVAP canister
    4.4. EVAP vapor pipe at the EVAP canister
  5. If you cannot locate a condition with the EVAP system, refer to Diagnostic Aids for additional information.

Component Testing
  1. Disconnect the EVAP vent line from the vent solenoid, and seal it, using a suitable plug or a plug from the J 41413-300 .
  2. Pressurize the EVAP system to 5 inches H20 with a J 41413-200 .
  3. Compare the Fuel Tank Pressure sensor parameter with a scan tool to the J 41413-200 pressure/vacuum gage. The scan tool FTP sensor parameter should be within 1 inch H20 of the pressure/vacuum gage.
  4. Remove the plug from the EVAP vent valve inlet.
  5. The scan tool Fuel Tank Pressure parameter should be 0 inches H20.
    6. ⇒If the FTP sensor parameters do not respond to the change in pressure, replace the FTP sensor.

Repair Instructions
    •  Evaporative Emission Canister Replacement
    •  Evaporative Emission Canister Vent Solenoid Valve Replacement
    •  Fuel Tank Pressure Sensor Replacement

Repair Verification
  1. Disconnect the EVAP vent line from the vent solenoid, and seal it, using a suitable plug or a plug from the J 41413-300 .
  2. Turn the nitrogen/smoke valve to nitrogen.
  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. Clear the DTCs with a scan tool.