Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
Observe the Freeze Frame/Failure Records for this DTC. Perform the Service Bay Test. Following the directions on the scan tool, perform the EVAP Service Bay Test. Does the scan tool indicate that the Service Bay Test passed? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
Inspect the EVAP system for the following conditions:
- A loose, missing, or damaged service port Schrader valve.
- A loose, incorrect, missing, or damaged fuel fill cap.
- A damaged EVAP purge solenoid.
Raise the vehicle on a hoist. Inspect the EVAP system for the following conditions:
- Any disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses.
- A damaged EVAP vent solenoid or EVAP canister.
Did you find and correct the condition? If yes, go to step 19. If no, go to next step.

NOTE: 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.

Turn ignition switch to OFF position. Connect the Evaporative Emissions System Tester (EEST) (J 41413-200), or equivalent, power supply clips to a known good 12-volt source. Install the Fuel Tank Cap Adapter (J 41415-40), or equivalent, to the fuel fill pipe. Connect the fuel fill cap to the fuel tank cap adapter. Connect the Nitrogen/Smoke Supply Hose (J 41413-200), or equivalent, to the fuel tank cap adapter. Turn ignition switch to RUN position, engine OFF. Command the EVAP vent solenoid closed using a scan tool. Turn the nitrogen/smoke valve on the EEST control panel to SMOKE. Use the remote switch to introduce smoke into the EVAP system. Use the EVAP Service Port Vent Fitting (J 41413-VLV), or equivalent, to open the EVAP service port. Remove the service port vent fitting once smoke is observed. Continue to introduce smoke into the EVAP system for an additional 60 seconds. Inspect the entire EVAP system for exiting smoke using the High Intensity White Light (J 41413-SPT), or equivalent. Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source? If yes, go to step 19. If no, go to next step.
Disconnect the fuel tank cap adapter from the fuel fill pipe. Install the fuel fill cap to the fuel fill pipe. Connect the nitrogen/smoke supply hose to the EVAP service port. Use the remote switch to introduce smoke into the EVAP system. Inspect the entire EVAP system for exiting smoke using the high intensity white light. Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source? If yes, go to step 19. If no, go to next step.
Use the remote switch to stop introducing smoke. Install the fuel tank cap adapter to the fuel fill pipe. Connect the EEST nitrogen/smoke supply hose to the fuel tank cap adapter. Connect the vehicle fuel fill cap to the fuel tank cap adapter. Command the EVAP vent solenoid open using a scan tool. Compare the Fuel Tank Pressure Sensor parameter, using a scan tool, to the EEST pressure/vacuum gauge. Is the scan tool Fuel Tank Pressure (FTP) sensor parameter within the specified value of the EEST pressure/vacuum gauge? If yes, go to next step. If no, go to step 16.
Seal the EVAP system using the EVAP Purge/Seal function using a scan tool. Turn the nitrogen/smoke valve on the EEST control panel to NITROGEN. Use the EEST to pressurize the EVAP system to 10 in. H2O. Is the FTP sensor parameter more than 5 in. H2O? If yes, go to next step. If no, go to step 16.
Use the remote switch to stop introducing nitrogen into the EVAP system. Increase the EVAP purge solenoid to 100 percent. Is the FTP sensor parameter less than one in. H2O? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
Disconnect the EVAP purge vacuum source from the EVAP purge solenoid. Is the FTP sensor parameter less than one in. H2O? If yes, go to step 13. If no, go to next step.
Disconnect the EVAP purge pipe from the EVAP purge solenoid. Is the FTP sensor parameter less than one in. H2O? If yes, go to step 17. If no, go to next step.
Disconnect the EVAP purge pipe at the EVAP canister. Is the FTP sensor parameter less than one in. H2O? If yes, go to step 15. If no, go to next step.
Disconnect the EVAP vapor pipe at the EVAP canister. Is the FTP sensor parameter less than one in. H2O? If yes, go to step 18. If no, go to step 14.
Repair the pinched or obstructed EVAP purge solenoid vacuum source. Did you complete the repair? After repair, go to step 19.
Repair the pinched or obstructed EVAP vapor pipe. Did you complete the repair? After repair, go to step 19.
Repair the restriction in the EVAP purge pipe? After repair, go to step 19.
Replace the FTP sensor. After repair, go to step 19.
Replace the EVAP purge solenoid? After repair, go to step 19.
Replace the EVAP canister? If yes, go to next step.
Following the directions on the scan tool, perform the EVAP Service Bay Test. Does the scan tool indicate that the Service Bay Test passed? If yes, go to next step. If no, go to step 3.
Using the scan tool, observe the stored information in CAPTURE INFO. Are there any DTCs that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.