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Home >> Mitsubishi >> 2001 >> Montero XLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0455: EVAP System Large Leak Detected >> Diagnostic Procedure
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Diagnostic Procedure

NOTE: The following test procedure requires functions available on manufacturer's MUT-II scan tool. Generic scan tools may not have the capability to carry out test.
NOTE: An improperly tightened fuel cap can cause this code to set. Check for properly installed fuel cap and a good seal between the fuel cap and fuel filler neck.
  1. Turn ignition off. Remove fuel cap. Push in flapper door to operate fuel overflow limiter valve. Fuel overflow limiter valve plunger should move toward top. Reinstall and tighten fuel cap 3 clicks. Remove fuel cap and check if fuel overflow limiter valve plunger was pushed back. Distance between tip of fuel overflow limiter valve plunger and top of fuel filler neck should be 1.1" (28 mm) or more. If fuel overflow limiter valve plunger does not return, replace fuel filler neck, install fuel cap and go to step  28. If fuel overflow limiter valve plunger is okay, install fuel cap and go to next step.
  2. Disconnect hose "A" at intake manifold side and connect hand vacuum pump to hose "A". Apply 5.8 psi (40 kPa) or less of vacuum. Vacuum should hold. If vacuum holds, go to step  4. If vacuum does not hold, go to next step.
  3. Using hand vacuum pump, check hose "A" for leaks. If leak is indicated, replace hose "A", then go to step  26. If leak is not indicated, replace purge solenoid, then go to step  26.
  4. Turn ignition on. Using scan tool, select actuator test item No. 8 (purge solenoid) and turn on (open) purge solenoid. Vacuum should leak. If vacuum leaks, go to step  11. If vacuum does not leak, go to next step.
  5. Using hand vacuum pump, check for clogging in hose "A". If clogging exists, replace hose "A", then perform purge flow check. See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. If clogging does not exist, go to next step.
  6. Disconnect hoses "A" and "B" from purge solenoid. See Figure and Figure . Connect hand vacuum pump to purge solenoid port from which hose "A" was disconnected. Using hand vacuum pump, apply vacuum. Vacuum should hold. Using scan tool, select actuator test item No. 8 (purge solenoid) and turn on (open) purge solenoid. Vacuum should leak. If purge solenoid does not operate, diagnose purge solenoid circuit problem. See DTC P0443: EVAPORATIVE EMISSION (EVAP) SYSTEM PURGE CONTROL MALFUNCTION . If purge solenoid operates and vacuum leaks as specified, go to next step. If purge solenoid operates and vacuum does not leak as specified, replace purge solenoid, then go to step  26.
  7. Turn ignition off. Using hand vacuum pump, check hoses "B" through "D" for clogging. See Figure and Figure . If clogging exists, replace appropriate hose, then go to step  26. If clogging does not exist, go to next step.
  8. Disconnect hoses "E", "D", and "U" at EVAP canister end. Connect hand vacuum pump to EVAP canister port from which hose "E" was disconnected. See Figure. Plug other 2 EVAP canister ports. Using hand vacuum pump, apply vacuum. Unplug each port in turn. Vacuum should leak as each port is unplugged. If vacuum leaks as specified, go to next step. If vacuum does not leak as specified, replace EVAP canister, then go to step  26.
  9. Using hand vacuum pump, check hoses "U" through "W" and air filter for clogging. If clogging exists, replace appropriate hose or air filter, then go to step  26. If clogging does not exist, go to next step.
  10. Disconnect hoses from ventilation solenoid. See Figure. Connect hand vacuum pump to ventilation solenoid port from which hose "U" was disconnected. Using hand vacuum pump, apply vacuum. Vacuum should leak. If vacuum leaks, go to step  26. If vacuum does not leak, replace ventilation solenoid, then go to step  26.
  11. Disconnect hose "U" at ventilation solenoid side. See Figure. Connect hand vacuum pump to ventilation solenoid port from which hose "U" was disconnected. Using hand vacuum pump, apply vacuum. Vacuum should leak. Turn ignition on. Using scan tool, select actuator test item No. 29 (ventilation solenoid) and turn ventilation solenoid on (closed). Using hand vacuum pump, apply vacuum. Vacuum should hold. If ventilation solenoid operates and holds vacuum as specified, go to next step. If ventilation solenoid operates but does not hold vacuum as specified, replace ventilation solenoid, then go to step  26. If ventilation solenoid does not operate properly, check ventilation solenoid circuit. See DTC P0446: EVAPORATIVE EMISSION (EVAP) SYSTEM VENT CONTROL MALFUNCTION .
  12. Confirm Miller EVAP System Pressure Pump (6872A) is operating properly. Perform self-test as described by manufacturer. Turn ignition off. Remove fuel cap. Remove fuel filler neck protector. Disconnect hose "I" from pipe between hoses "I" and "H". Plug end of hose "I". See Figure and Figure . Connect EVAP system pressure pump to fuel filler neck. Perform pressure test (I/M240 simulation test) described in EVAP system pressure pump manufacturer's instructions located in lid of pump box. If leak is not indicated, go to next step. If leak is indicated, go to step  17.
  13. Reconnect hose "I" to pipe between hoses "I" and "H". Disconnect hose "E" at EVAP canister end and plug hose end. See Figure. Repeat pressure test. If leak is indicated, go to step  20. If leak is not indicated, go to next step.
  14. Remove plug from hose "E". If air bleeds from hose "E" and pressure in fuel tank decreases, go to next step. If air does not bleed from hose "E" and pressure in fuel tank does not decrease, go to step  23.
  15. Using hand vacuum pump, check hoses "B" through "D" and "U" for leaks. See Figure, Figure, and Figure . If leak is indicated, replace appropriate hose, then go to step  26. If leak is not indicated, go to next step.
  16. Disconnect hoses "E", "D", and "U" at EVAP canister end. Connect hand vacuum pump to EVAP canister port from which hose "E" was disconnected. See Figure. Plug other 2 EVAP canister ports. Using hand vacuum pump, apply vacuum. Vacuum should hold. If vacuum leaks, replace EVAP canister, then go to step  26. If vacuum does not leak, go to step  26.
  17. Remove fuel filler neck assembly. Using hand vacuum pump, check hoses "I", "K", "L", "M", "O", "P", "R", and "S" for leaks. See Figure. If leak is indicated, replace appropriate hose, install fuel filler neck assembly, then go to step  26. If leak is not indicated, go to next step.
  18. Remove fuel tank. Using hand vacuum pump, check for leaks in hoses "J", "Q", "N", and "T". See Figure and Figure . If leak is indicated, replace appropriate hose, install fuel tank, then go to step  26. If leak is not indicated, go to next step.
  19. Visually check fuel tank for cracks and leaks. Connect EVAP system pressure pump to fuel return hose. See Figure. Plug all openings on fuel tank. Using EVAP system pressure pump, pressurize fuel tank. Check for leaks by applying soap to each section of fuel tank. Repair leak or replace fuel tank as necessary, install fuel tank, then go to step  26.
  20. Using hand vacuum pump, check hose "E" for leaks. If leak is indicated, replace hose, then go to step  26. If leak is not indicated, go to next step.
  21. Remove filler neck assembly. Using hand vacuum pump, check hose "H" for leaks. See Figure. If leak is indicated, replace hose, install fuel filler neck assembly, then go to step  26. If leak is not indicated, go to next step.
  22. Remove fuel tank. Using hand vacuum pump, check hoses "F" and "G" for leaks. See Figure and Figure . If leak is indicated, replace appropriate hose, install fuel tank and fuel filler neck assembly, then go to step  26. If leak does not exist, install fuel tank and fuel filler neck assembly, then go to step  26.
  23. Using hand vacuum pump, check hose "E" for clogging. If clogging exists, replace hose, then go to step  28. If clogging does not exist, go to next step.
  24. Remove fuel filler neck assembly. Using hand vacuum pump, check hoses "H" and "I" for clogging. See Figure and Figure . If clogging exists, replace appropriate hose and install fuel filler neck assembly, then go to step  28. If clogging does not exist, go to next step.
  25. Remove fuel tank. Using hand vacuum pump, check hoses "F" and "G" for clogging. See Figure and Figure . If clogging exists, replace appropriate hose, install fuel tank and fuel filler neck assembly, then go to step  28. If clogging does not exist, install fuel tank and fuel filler neck assembly, then go to next step.
  26. Ensure transaxle is in Park and fuel cap is securely tightened. Start engine and let idle. Clear DTCs. Using MUT-II scan tool, start EVAP system leak monitor test. Select SYSTEM TEST and press YES key. Select EVAP LEAK MON and press YES key. During monitor, keep accelerator pedal in idling position. Go to next step.
    NOTE: Monitor test will automatically increase engine speed. If engine speed does not reach 2000 RPM during monitor test, adjustment of fixed Speed Adjusting Screw (SAS) may be needed. See FIXED SPEED ADJUSTING SCREW under IDLE SPEED & MIXTURE in ON-VEHICLE ADJUSTMENTS article.
  27. When monitor starts, IN PROGRESS item on scan tool will change from NO to YES. If EVAP LEAK MON. COMPLETED. TEST PASSED is displayed, EVAP system currently is working properly. Code was probably set by improperly installed fuel cap. If EVAP LEAK MON. COMPLETED. TEST FAILED & DTCS SET is displayed, go to step  2. If EVAP LEAK MON. DISCONTINUED is displayed, turn ignition off and start monitor over. Go to step  26.
  28. Test drive vehicle following OBD-II drive cycle EVAP system leak monitor pattern. See EVAP SYSTEM LEAK MONITOR under OBD-II DRIVE CYCLES under VERIFYING REPAIRS. Check for DTCs. If DTC P0455 is output, retry diagnostic procedure. If DTC P0455 is not output, inspection is complete.
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