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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 STS 🢒 Engine 🢒 Engine Controls - 4.6L (LH2) 🢒 DTC P0455

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 solenoid valve OPEN and the EVAP canister 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.

Control Module Command

EVAP Canister Purge Solenoid Valve

EVAP Canister Vent Solenoid Valve

ON

Open

Closed

OFF

Closed

Open

DTC Descriptor

This diagnostic procedure supports the following DTC:

P0455 EVAP System Large Leak Detected

Conditions for Running the DTC
    • DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P0068, P0101, P0102, P0103, P0111, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0139, P0140, P0141, P0150, P0151, P0152, P0153, P0154, P0155, P0156, P0157, P0158, P0159, P0160, P0161, P0201, P0202, P0203, P0204, P0205, P0206, P0221, P0222, P0223, P0308, P0313, P0443, P0446, P0449, P0452, P0453, P0454, P0458, P0459, P0496, P0498, P0499, P0506, P0507, P1271, P1277, P1278, P1282, P1283, P1511, P1516, P1519, P1523, P1526, P1530, P1551, P2107, P2108, P2100, P2101, P2119, P2122, P2123, P2127, P2128, P2138, P2176 are not set.
    • The engine run time is more than 2 minutes.
    • The ignition voltage is between 10-18 volts.
    • The barometric pressure (BARO) is more than 70 kPa.
    • The fuel level is between 15-85 percent.
    • The engine coolant temperature (ECT) is more than 75°C (167°F).
    • The vehicle speed is less than 8 km/h (5 mph).
    • The FTP is between -1.7 and +0.1 kPa (-7.0 and +0.4 in H2O).
    • The FTP must have varied at least once.
    • The vehicle is operating in Closed Loop.

Conditions For Setting the DTC

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

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 3 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 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.
    • A loose, incorrect, missing, or damaged fuel fill cap may cause this DTC to set.
    • A temporary blockage in the EVAP purge solenoid valve, purge pipe or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.
    • 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, sealing the system and observing the FTP parameter for vacuum decay, this type of leak may be detected.
    • To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .
    • 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.
    • For intermittent conditions, refer to Intermittent Conditions .

Test Description

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

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

Step

Action

Values

Yes

No

Schematic Reference: Evaporative Emissions Hose Routing Diagram

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Inspect the evaporative emission (EVAP) system for the following conditions:
    2. • A loose, missing, or damaged service port Schrader valve
    • A loose, incorrect, missing, or damaged fuel fill cap
    • A damaged EVAP purge solenoid valve
  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. • Any disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses
    • A damaged EVAP canister vent solenoid valve or EVAP canister

Did you find and correct the condition?

--

Go to Step 16

Go to Step 3

3

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

  1. Turn OFF the ignition.
  2. Connect the J 41413-200 Evaporative Emissions System Tester (EEST) power supply clips to a known good 12-volt source.
  3. Turn the nitrogen/smoke valve to nitrogen.
  4. Connect the nitrogen/smoke hose to the 0.5 mm (0.02 in) test orifice on the bottom-front of the J 41413-200 .
  5. Use the remote switch to activate the J 41413-200 .
  6. Align the red flag on the flow meter with the floating indicator. Use the remote switch to de-activate the J 41413-200 .
  7. Install the J 41415-40 or GE-41415-50 Fuel Tank Cap Adapter to the fuel fill pipe.
  8. Install the fuel fill cap to the J 41415-40 or GE-41415-50 .
  9. Remove the nitrogen/smoke hose from the test orifice and install the hose onto the J 41415-40 or GE-41415-50 .
  10. Turn ON the ignition, with the engine OFF.
  11. Command the EVAP canister vent solenoid valve closed with a scan tool.
  12. Use the remote switch to introduce nitrogen and fill the EVAP System until the floating indicator stabilizes.
  13. Compare the flow meter stable floating indicator position to the red flag.

Is the floating indicator below the red flag?

--

Go to Step 6

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. 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 J 41415-40 or GE-41415-50 to the fuel fill pipe.
  4. Connect the J 41413-200 nitrogen/smoke supply hose to the J 41415-40 or GE-41415-50 .
  5. Turn ON the ignition, with the engine OFF.
  6. Command the EVAP canister vent solenoid 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 Service Port Vent Fitting to open the EVAP service port.
  10. Remove the J 41413-VLV once 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 16

Go to Step 5

5
  1. Disconnect the J 41415-40 or 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 16

Go to Step 6

6

  1. Use the remote switch to stop introducing smoke.
  2. Install the J 41415-40 or 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 J 41415-40 or GE-41415-50 .
  4. Command the EVAP canister vent solenoid valve Open with a scan tool.
  5. Compare the fuel tank pressure sensor parameter with a scan tool to the J 41413-200 pressure/vacuum gage.

Is the difference between the scan tool fuel tank pressure sensor parameter and the pressure/vacuum gage on the J 41413-200 within the specified value?

1 in H2O

Go to Step 7

Go to DTC P0451

7

  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 the first specified value.
  4. Observe the fuel tank pressure sensor parameter with a scan tool.

Is the fuel tank pressure sensor parameter more than the second specified value?

10 in H2O

5 in H2O

Go to Step 8

Go to DTC P0451

8
  1. Use the remote switch to stop introducing nitrogen into the EVAP system.
  2. Increase the EVAP canister purge solenoid valve 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 canister purge pipe from the EVAP purge solenoid valve.

Is the fuel tank pressure sensor parameter less than the specified value?

1 in H2O

Go to Step 13

Go to Step 10

10

Disconnect the EVAP purge pipe at the EVAP canister.

Is the fuel tank pressure sensor parameter less than the specified value?

1 in H2O

Go to Step 14

Go to Step 11

11

Disconnect the EVAP vapor pipe at the EVAP canister.

Is the fuel tank pressure sensor parameter less than the specified value?

1 in H2O

Go to Step 15

Go to Step 12

12

Repair the pinched or obstructed EVAP vapor pipe.

Did you complete the repair?

--

Go to Step 16

--

13

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

Did you complete the replacement?

--

Go to Step 16

--

14

Repair the restriction in the EVAP purge pipe.

Did you complete the repair?

--

Go to Step 16

--

15

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

Did you complete the replacement?

--

Go to Step 16

--

16

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 (0.02 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 J 41415-40 or GE-41415-50 to the fuel fill pipe.
  6. Remove the nitrogen/smoke hose from the test orifice and install the hose onto the J 41415-40 or GE-41415-50 .
  7. Turn ON the ignition, with the engine OFF.
  8. Command the EVAP vent solenoid valve Closed with a scan tool.
  9. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating stabilizes.
  10. Compare the flow meter stable floating indicator position to the red flag.

Is the floating indicator below the red flag?

5 in H2O

Go to Step 17

Go to Step 3

17
  1. Observe the J 41413-200 pressure/vacuum gage.
  2. Increase the EVAP canister purge solenoid valve to 100 percent.

Does the pressure decrease?

--

Go to Step 18

Go to Step 9

18

Compare the fuel tank pressure sensor parameter with a scan tool to the J 41413-200 .

Is the difference between the scan tool fuel tank pressure sensor parameter and the pressure/vacuum gage on the J 41413-200 within the specified value?

1 in H2O

Go to Step 19

Go to DTC P0451

19

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