FixVault
Home › Cadillac › 2000 › Seville SLS › Repair and Diagnosis › Engine Performance › System › Engine Control System - Self-Diagnostics - 4.6L › Diagnostic Tests › DTC P0446: EVAP Vent System Performance › Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Using scan tool, check if DTC P0449 is stored as history. If DTC P0449 is set, diagnose DTC P0449 first. See DTC P0449: EVAP VENT SOLENOID CONTROL CIRCUIT . If DTC P0449 is not set, go to next step.
  3. Check for improperly routed, kinked or damaged EVAP system lines. Check for damaged EVAP system component(s). Repair or replace as necessary. After repairs, go to step  13. If no problems were found, go to next step.
  4. Turn ignition off. Remove fuel filler cap. Wait 30 seconds and then replace fuel cap. Turn ignition on, engine off. Using scan tool, monitor EVAP fuel tank pressure sensor display. If scan tool reading is zero in. H2O, go to next step. If scan tool reading is not zero in. H2O, go to step  8.
  5. Start and operate engine at idle. Using scan tool, select EVAP PURGE/SEAL function. While monitoring EVAP fuel tank pressure sensor display, command EVAP purge to obtain -10 in. H2O. While monitoring EVAP fuel tank pressure sensor display, command EVAP vent valve open (pressing EXIT). If EVAP fuel tank pressure sensor quickly drops to near zero in. H2O when zero percent EVAP purge is commanded and vent valve is opened, see DIAGNOSTIC AIDS . If reading is not as specified, go to next step.
  6. Monitor fuel tank pressure display on scan tool while disconnecting EVAP vent line from EVAP canister. If fuel tank pressure is zero in. H2O, go to next step. If fuel tank pressure is not zero in. H2O, go to step  9.
  7. Disconnect EVAP vent line from vent valve. Connect a hand-held vacuum pump to EVAP vent valve. Using scan tool, command EVAP vent valve on (closed). Using vacuum pump, apply 5 in. Hg, then command vent valve off (open). If vacuum drops to zero, go to step  10. If vacuum does not drop to zero, go to step  11.
  8. Check for open fuel tank pressure sensor ground circuit. Repair as necessary. After repairs, go to step  13. If circuit is okay, go to step  12.
  9. Replace EVAP canister. After replacing canister, go to step  13.
  10. Replace EVAP vent line. After replacing vent line, go to step  13.
  11. Replace EVAP vent valve. After replacing vent valve, go to step  13.
  12. Replace EVAP fuel tank pressure sensor.
  13. Using scan tool, review and record FREEZE FRAME and FAIL RECORDS data. Clear DTCs. Operate vehicle within parameter for setting this DTC. Using scan tool, monitor SPECIFIC DTC INFO for this DTC until test runs. If scan tool indicate that this DTC failed this ignition, go to step  3. If scan tool does not indicate that this DTC failed this ignition, system is okay.
About FixVault