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Home >> Buick >> 1996 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - 2.2L >> Diagnostic Trouble Codes >> DTC P0441 - EVAP System Incorrect Purge Flow >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command EVAP canister purge solenoid on. If solenoid is on (click will be heard or felt), go to next step. If solenoid is off, go to step 4).
  3. Disconnect throttle body-to-EVAP canister purge solenoid vacuum hose at solenoid. Install a vacuum gauge to disconnected hose. Start engine. Increase engine speed to 2500 RPM. While observing vacuum gauge, momentarily snap throttle open. If vacuum is greater than 10 in. Hg, go to step 5). If vacuum is 10 in. Hg or less, see DIAGNOSTIC AIDS.
  4. Disconnect purge solenoid connector. With test light connected to ground, probe EVAP ignition feed circuit terminal at purge solenoid harness connector. If test light is on, go to step 6). If test light is off, go to step 7).
  5. Turn ignition on, with engine off. Disconnect EVAP canister purge vacuum switch connector. Using scan tool, view ENGINE 1 screens. If EVAP VACUUM SWITCH indicates ON, go to step 8). If EVAP VACUUM SWITCH does not indicate ON, go to step 9).
  6. With a test light connected to positive battery terminal, probe EVAP driver circuit terminal at purge solenoid harness connector. Using scan tool, command EVAP canister purge solenoid on. If test light flashes on when purge solenoid is commanded on, go to step 12). If test light does not flash on when purge solenoid is commanded on, go to step 13).
  7. Repair open in ignition feed circuit. After repair is completed, go to step 14).
  8. Inspect vacuum switch vacuum hoses for being pinched, blocked or kinked. Replace hoses as necessary. After repair is completed, go to step 14). If vacuum hoses are okay, go to step 10).
  9. Check for short to voltage in EVAP vacuum switch signal circuit. Repair as necessary. After repair is completed, go to step 14). If circuit is okay, go to step 11).
  10. Replace defective EVAP vacuum switch. After repair is completed, go to step 14).
  11. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 14).
  12. Replace EVAP canister purge solenoid. After repair is completed, go to step 14).
  13. Check for open, short to voltage or short to ground inn EVAP driver circuit. Repair as necessary. After repair is completed, go to next step. If circuit is okay, go to step 11).
  14. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0441. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
  15. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.
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