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Home >> Pontiac >> 2007 >> Vibe Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - DTC P0452 To DTC P2138 >> DTC P0456 >> Test Description

Test Description

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

  1. 4:  Waiting until smoke is seen before plugging the EVAP canister vent line speeds up the filling of the canister and fuel tank with smoke. Introducing smoke in between 60-second intervals of Nitrogen also increases the speed of the filling of smoke in the fuel tank, the filler pipe vapor space, and the EVAP canister. This occurs because the pressure at which Nitrogen gas is applied is greater than the pressure at which smoke is introduced. The Nitrogen gas pushes the smoke that was just introduced through the canister and into the fuel tank. The EVAP vent solenoid DOES NOT have to be turned ON in order to test for leaks. The installation of the adapter J 41413-323 or J 41413-324 seals the tank side of the EVAP system.
  2. 5:  This test verifies that the FTP sensor is accurate. The FTP sensor should indicate little or no pressure with fuel fill pipe open. An FTP sensor that does not correctly respond to vacuum, or pressure may cause this DTC to set.
  3. 6:  This step tests the operation of the EVAP vent solenoid located in the EVAP vacuum leak pump assembly. If the vent solenoid passage leaks, the EVAP system leak diagnostic will fail and set a DTC. This internal leak is not detected using the J 41413-200 EEST.
  4. 7:  This step verifies whether a leak in the EVAP system still exists. If the flow gage on the EEST and/or the scan tool pressure reading remain constant, there is no external leak. If the EEST gage indicates flow, or the scan tool pressure reading decreases, there is still an external leak in the EVAP system.
  5. 8:  This step tests the fuel tank assembly for leaks with the tank removed from the vehicle. The J 41413-300 EVAP Cap and Plug Kit enables you to use smoke to test for a leak on the portions of the fuel tank that are not visible when installed in the vehicle.
DTC P0456

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
2 Inspect the evaporative emission (EVAP) system for the following conditions:
  • A loose, incorrect, missing, or damaged fuel fill cap
  • A damaged EVAP purge solenoid

Did you find and correct the condition?		 - Go to Step 7  Go to Step 3 
3
  1. Raise the vehicle on a hoist. Refer to Lifting and Jacking the Vehicle .
  2. Inspect the EVAP system for the following conditions:
    • Any disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses
    • A damaged EVAP canister, line, or fitting.
Did you find and correct the condition?		 - Go to Step 7  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. Remove the fuel fill cap and install the GE-41415-50-A  Fuel Tank Cap Adapter. See Special Tools .
  2. Connect the nitrogen/smoke supply hose of the J 41413-200  Evaporative Emission System Tester (EEST) to the correct fuel tank cap adapter. See Special Tools .
  3. Disconnect the EVAP filter hose, inlet side, at the 13 mm (0.5 in) diameter steel vent pipe. The EVAP filter hose has a quick connect fitting. Refer to Evaporative Emission Canister Filter Replacement
  4. Use the remote switch to introduce smoke into the EVAP system.
  5. Continue to introduce smoke for approximately 1 minute.
  6. Turn the nitrogen/smoke valve on the control panel to NITROGEN.
  7. Use the remote switch to introduce Nitrogen gas into the EVAP system for 60 seconds.
  8. Continue to introduce smoke, then Nitrogen, at 60 second intervals, until smoke is seen exiting the open EVAP filter hose.
  9. Plug the open end of the EVAP filter hose with the J 41413-324 adapter from the J 41413-300  EVAP Cap and Plug kit. See Special Tools .
  10. With the system now sealed, again introduce smoke, then Nitrogen, at 60 second intervals, while searching for exiting smoke.
  11. Inspect the entire EVAP system for exiting smoke with the J 41413-SPT  High Intensity Lamp. See Special Tools .
Did you locate and repair a leak source?		 - Go to Step 7  Go to Step 5 
5 
  1. Remove the fuel tank adapter from the fuel fill pipe.
  2. Observe the fuel tank pressure (FTP) sensor with a scan tool.
Is the FTP sensor voltage within the specified range?		 3.5-3.8 V Go to Step 6  Go to DTC P0451
6 
  1. Remove the EVAP canister from the vehicle. Refer to Evaporative Emission Canister Replacement .
  2. Test the operation EVAP canister and EVAP vacuum leak pump assembly. Refer to Evaporative Emission Control System Diagnosis .
Did the EVAP components pass all tests?		 - Go to Step 7  Go to Step 10 
7 
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. Remove the fuel fill cap and install GE-41415-50-A  . See Special Tools .
  2. Connect the nitrogen/smoke supply hose of the J 41413-200  to the correct fuel tank cap adapter. See Special Tools .
  3. Disconnect the EVAP filter hose, inlet side, at the 13 mm (0.5 in) diameter steel vent pipe and plug the open end of the hose with the J 41413-324 adapter from the J 41413-300  The vent hose has a quick connect fitting. See Special Tools . Refer to Evaporative Emission Canister Filter Replacement .
  4. Turn the nitrogen/smoke valve to NITROGEN.
  5. Pressurize the EVAP system until the flow gage indicator on the EEST has dropped to a no flow position.
  6. Observe the flow gage, or the FTP sensor on the scan tool for 5 minutes.
Did the flow gage indicator remain in the no flow position?		 - Go to Step 9  Go to Step 8 
8 
  1. Remove the fuel tank. Refer to Fuel Tank Replacement .
  2. Connect the J 41413-200  to the fuel tank using the correct fitting from the J 41413-300  . See Special Tools .
  3. Seal all the fuel tank openings with the J 41413-300  and use smoke in order to test the fuel tank assembly for leaks. See Special Tools .
  4. If a leak is found, repair or replace the fuel tank as necessary.
  5. If no fuel tank leak is found, install the fuel tank.
Did you find and correct a condition?		 - Go to Step 11  Go to Step 4 
9
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition, with the engine OFF.
  4. Perform the EVAP service bay test with the scan tool. Refer to EVAP Service Bay Test in Service Bay Test .
Are there any EVAP DTCs set in Last Test Failed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Diagnostic Aids
10 Replace the EVAP vacuum leak pump.
Did you complete the replacement?		 - Go to Step 11  -
11 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 System OK
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