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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 Allure 🢒 Engine 🢒 Engine Controls - 3.6L (LY7) 🢒 DTC P0455
Table 1: DTC P0455 Evaporative Emission (EVAP) System Large Leak Detected

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

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0455 Evaporative Emission (EVAP) System Large Leak Detected

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 12-88 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
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • 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
    • The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
    • To help locate intermittent leaks, use the J 41413-200 Evaporative Emission 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.
    • 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.
    • A loose, incorrect, missing, or damaged fuel fill cap may cause this DTC to set.
    • 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.
    • For an intermittent condition, refer to Intermittent Conditions .

Test Description

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

  1. 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. This step verifies proper operation of the FTP sensor.

    3.

  3. A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6 inches of H2O and 7 inches of H2O.

    4.

  4. This step tests the EVAP purge solenoid vacuum source between the EVAP purge solenoid and the Intake manifold for restrictions or blockages.

DTC P0455 Evaporative Emission (EVAP) System Large Leak Detected

Step

Action

Values

Yes

No

Schematic Reference: Evaporative Emissions Hose Routing Diagram

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

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

  1. Turn the nitrogen/smoke valve to nitrogen.
  2. Connect the nitrogen/smoke hose to the 0.5 mm (0.020 in) test orifice on the bottom-front of the J 41413-200 Evaporative Emission System Tester (EEST).
  3. Use the remote switch to activate the J 41413-200 .
  4. Align the red flag on the flow meter with the floating indicator. Use the remote switch to de-activate the J 41413-200 .
  5. Install the GE-41415-50 Fuel Tank Cap Adapter to the fuel fill pipe.
  6. Remove the nitrogen/smoke hose from the test orifice and install the hose onto the GE-41415-50 .
  7. Turn ON the ignition, with the engine OFF.

    8. Important: The DTCs may need to be cleared if the output control does not operate.

  8. Command the evaporative emission (EVAP) vent solenoid closed with a scan tool.
  9. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating indicator stabilizes.
  10. Compare the flow meter's stable floating indicator position to the red flag.

Is the floating indicator below the red flag?

--

Go to Step 7

Go to Step 3

3
  1. Inspect the EVAP system for the following conditions:
    2. • Loose, missing, or damaged service port schrader valve
    • Loose, incorrect, missing, or damaged fuel fill cap
    • A damaged EVAP purge solenoid
  2. Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle in General Information.
  3. Inspect the EVAP system for the following conditions:
    4. • Disconnected, incorrectly routed, kinked, or damaged EVAP pipes and hoses
    • A damaged EVAP vent valve or EVAP canister

Did you find and correct the condition?

--

Go to Step 19

Go to Step 4

4

Important: 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 OFF the ignition.
  2. Connect the J 41413-200 power supply clips to a known good 12-volt source.
  3. Install the GE-41415-50 to the fuel fill pipe.
  4. Connect the J 41413-200 nitrogen/smoke supply hose to the GE-41415-50 .
  5. Turn ON the ignition with the engine OFF.

    6. Important: The DTCs may need to be cleared if the output control does not operate.

  6. Command the EVAP vent valve closed with a scan tool.
  7. Turn the nitrogen/smoke valve on the J 41413-200 control panel to SMOKE.
  8. Use the remote switch to introduce smoke into the EVAP system.
  9. Use the J 41413-VLV EVAP Port Vent Fitting tool to open the EVAP service port.
  10. Remove the J 41413-VLV once the smoke is observed.
  11. Continue to introduce smoke into the EVAP system for an additional 60 seconds.
  12. Inspect the entire EVAP system for exiting smoke with the J 41413-SPT High Intensity White Light.
  13. Continue to introduce smoke at 15-second intervals until the leak source has been located.

Did you locate and repair a leak source?

--

Go to Step 19

Go to Step 5

5

  1. Disconnect the GE-41415-50 from the fuel fill pipe.
  2. Install the fuel fill cap to the fuel fill pipe.
  3. Connect the J 41413-200 nitrogen/smoke supply hose to the EVAP service port.
  4. Use the remote switch to introduce smoke into the EVAP system.
  5. Inspect the entire EVAP system for exiting smoke with the J 41413-SPT .
  6. Continue to introduce smoke at 15-second intervals until the leak source has been located.

Did you locate and repair a leak source?

--

Go to Step 19

Go to Step 6

6

  1. Use the remote switch to stop introducing smoke.
  2. Install the GE-41415-50 to the fuel fill pipe.
  3. Connect the J 41413-200 nitrogen/smoke supply hose and vehicle fuel fill cap to the GE-41415-50 .

    4. Important: The DTCs may need to be cleared if the output control does not operate.

  4. Command the EVAP vent valve open with a scan tool.
  5. Compare the Fuel Tank Pressure parameter with a scan tool to the J 41413-200 pressure/vacuum gage.

Is the scan tool Fuel Tank Pressure parameter within the specified value of the J 41413-200 pressure/vacuum gage?

1 in H2O

Go to Step 7

Go to Step 15

7

    Important: The DTCs may need to be cleared if the output control does not operate.

  1. Seal the EVAP system using the EVAP Purge/Seal function with a scan tool.
  2. Turn the nitrogen/smoke valve on the J 41413-200 control panel to NITROGEN.
  3. Use the J 41413-200 to pressurize the EVAP system to 10 inches H2O.

Is the Fuel Tank Pressure sensor parameter more than the specified value?

5 in H2O

Go to Step 8

Go to Step 15

8

  1. Use the remote switch to stop introducing nitrogen into the EVAP system.
  2. Increase the EVAP purge solenoid to 100 percent.

Is the Fuel Tank Pressure sensor parameter less than the specified value?

1 in H2O

Go to Diagnostic Aids

Go to Step 9

9

Disconnect the EVAP purge vacuum source from the EVAP purge solenoid.

Is the Fuel Tank Pressure parameter less than the specified value?

1 in H2O

Go to Step 13

Go to Step 10

10

Disconnect the EVAP purge pipe from the EVAP purge solenoid.

Is the Fuel Tank Pressure parameter less than the specified value?

1 in H2O

Go to Step 16

Go to Step 11

11

Disconnect the EVAP purge pipe at the EVAP canister.

Is the Fuel Tank Pressure parameter less than the specified value?

1 in H2O

Go to Step 17

Go to Step 12

12

Disconnect the EVAP vapor pipe at the EVAP canister.

Is the Fuel Tank Pressure parameter less than the specified value?

1 in H2O

Go to Step 18

Go to Step 14

13

Repair the pinched or obstructed EVAP purge solenoid vacuum source.

Did you complete the repair?

--

Go to Step 19

--

14

Repair the pinched or obstructed EVAP vapor pipe.

Did you complete the repair?

--

Go to Step 19

--

15

Replace the fuel tank pressure (FTP) sensor. Refer to Fuel Tank Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 19

--

16

Replace the EVAP purge solenoid. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .

Did you complete the replacement?

--

Go to Step 19

--

17

Repair the restriction in the EVAP purge pipe. Refer to Evaporative Emission Hoses/Pipes Replacement - Chassis/Canister .

Did you complete the repair?

--

Go to Step 19

--

18

Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement .

Did you complete the replacement?

--

Go to Step 19

--

19

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

  1. Turn the nitrogen/smoke valve to nitrogen.
  2. Connect the nitrogen/smoke hose to the 0.5 mm (0.020 in) test orifice on the bottom-front of the J 41413-200 .
  3. Use the remote switch to activate the J 41413-200 .
  4. Align the red flag on the flow meter with the floating indicator. Use the remote switch to de-activate the J 41413-200 .
  5. Install the GE-41415-50 to the fuel fill pipe.
  6. Remove the nitrogen/smoke hose from the test orifice and install the hose onto the GE-41415-50 .
  7. Turn ON the ignition, with the engine OFF.

    8. Important: The DTCs may need to be cleared if the output control does not operate.

  8. Command the EVAP vent solenoid closed with a scan tool.
  9. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating indicator stabilizes.
  10. Compare the flow meter's stable floating indicator position to the red flag.

Is the floating indicator below the red flag?

--

Go to Step 20

Go to Step 4

20
  1. Clear the DTCs with a scan tool.
  2. Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK