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Home >> Cadillac >> 1996 >> Seville SLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0441 - EVAP System No Flow During Purge >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Check if DTC P1645 is also present. If DTC P1645 is present, diagnose DTC first. If DTC P1645 is not present, go to next step.
  3. Start engine. Using scan tool, select EVAP VACUUM SW. Command EVAP solenoid on (100 percent). If scan tool reads PURGING, go to next step. If scan tool does not read PURGING, go to step 12).
  4. Disconnect EVAP vacuum switch connector. If scan tool reads PURGING, go to next step. If scan tool does not read PURGING, go to step 12).
  5. Reconnect EVAP switch connector. Disconnect EVAP vacuum switch vacuum hose (solenoid side) and install a "T" fitting between vacuum hose to solenoid. Connect a vacuum gauge to fitting. Start engine. Check vacuum with engine at idle and EVAP solenoid commanded on (100 percent). If vacuum reading is 4 in. Hg or greater, go to next step. If vacuum reading is less than 4 in. Hg, go to step 7).
  6. Replace EVAP vacuum switch.
  7. Disconnect EVAP control solenoid vacuum hose (intake manifold side). Connect vacuum gauge to hose and check vacuum with engine running. If vacuum reading is 4 in. Hg or greater, go to next step. If vacuum reading is less than 4 in. Hg, go to step 9).
  8. Reconnect vacuum hose to EVAP control solenoid. Disconnect vacuum hose on other side (switch side) of EVAP control solenoid. Connect vacuum gauge on solenoid port. Check vacuum reading with engine running and EVAP control solenoid commanded on (100 percent). If vacuum reading is 4 in. Hg or greater, go to step 11). If vacuum reading is less than 4 in. Hg, go to step 10).
  9. Repair blocked or leaking vacuum hose between intake manifold and EVAP control solenoid.
  10. Replace EVAP control solenoid.
  11. Check for vacuum leak in system between EVAP control solenoid and vapor canister, including switch. Repair as necessary. If vacuum leak is not present, go to step 13).
  12. Repair short to ground in EVAP vacuum switch input circuit.
  13. Replace vapor canister.
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