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Home >> Mitsubishi >> 2002 >> Diamante LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0455: EVAP Control 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 all tests. An improperly tightened fuel cap can cause this DTC to set. Check for properly installed fuel cap and a good seal between the fuel cap and fuel filler neck.
NOTE: When fuel nozzle is inserted into filler neck and flapper door is opened, fuel overflow limiter valve plunger moves toward top of neck and closes fuel overflow limiter valve. When fuel cap is installed, cap pushes fuel overflow limiter valve plunger back in, which opens fuel overflow limiter valve. If flapper door or fuel overflow limiter valve plunger do not operate properly, vapor passage will be blocked and DTC may set.
  1. 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 completely, replace fuel filler neck. After repairs, go to step  24. If fuel overflow limiter valve plunger is okay, reinstall fuel cap and go to next step.
  2. Disconnect hose "A" from intake manifold. Connect a hand-held vacuum pump to hose "A". See Fig 1. Apply 12 in. Hg (40 kPa) or less of vacuum. If vacuum holds, go to step  5. If vacuum does not hold, go to next step.
  3. Using vacuum pump, check hose "A" for leaks. Replace hose as necessary. After repairs, go to step  22. If problem does not exist, go to next step.
  4. Connect MUT-II scan tool to OBD-II Data Link Connector (OBD-II DLC). Turn ignition on. Disconnect hose "B" from purge solenoid. Connect hand-held vacuum pump to purge solenoid port. See Figure. Apply vacuum. Vacuum should hold. Using scan tool, select actuator test No. 8 (purge solenoid). Vacuum should leak and atmospheric pressure returned to when purge solenoid is actuated. If purge solenoid performs as specified, go to step  22. If vacuum does not leak when purge solenoid actuates, replace purge solenoid. After replacing solenoid, go to step  22. If purge solenoid does not actuate, check purge solenoid circuit. See DTC P0443: EVAP EMISSION CONTROL SYSTEM PURGE CONTROL VALVE CIRCUIT MALFUNCTION .
  5. Connect MUT-II scan tool to OBD-II Data Link Connector (OBD-II DLC). Using scan tool, select actuator test No. 8 (purge solenoid). If vacuum leaks when purge solenoid is actuated, go to step  7. If vacuum does not leak when purge solenoid is actuated, go to next step.
  6. Using hand-held vacuum pump, check for clogging in hoses "A" and "B" and line between hoses "A" and "B". If problem does not exist, go to step  4. If problem exists, repair as necessary. After repairs, perform purge flow check. See PURGE CONTROL SYSTEM CHECK (PURGE FLOW CHECK) under FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article.
  7. Lower EVAP canister assembly, located at left rear of vehicle. Disconnect hose "G" from ventilation solenoid. Connect vacuum pump to ventilation solenoid. See Figure. Apply vacuum. Vacuum should leak. Using scan tool, select actuator test item No. 29 (ventilation solenoid). Apply vacuum. Vacuum should hold. If ventilation solenoid performs as specified, to next step. If ventilation solenoid operates, but vacuum leaks when ventilation solenoid is actuated, replace ventilation solenoid. After replacing solenoid, go to step  22. If ventilation solenoid does not operate, check ventilation solenoid circuit. See DTC P0446: EVAP EMISSION CONTROL SYSTEM VENTILATION SOLENOID CONTROL CIRCUIT .
    8. NOTE: Before pressure testing, confirm Miller EVAP System Pressure Pump (6872A) is operating properly. Perform self-test procedures described in manufacturer's instructions.
  8. Using locking pliers, pinch hose "G" between EVAP canister and ventilation solenoid. See 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 indicated, go to next step. If no leak is indicated, go to step  16.
  9. Disconnect hose "I" from liquid separator assembly and plug liquid separator assembly port. See Figure. Repeat pressure test. If leak is indicated, go to step  12. If no leak is indicated, go to next step.
  10. Using vacuum pump, check for leaks in hoses "C" through "G". See Figure and Figure . Replace hose(s) that leak. After repairs, go to step  22. If problem does not exist, go to next step.
  11. Connect vacuum pump to EVAP canister port from which hose "G" was disconnected. Plug other 2 EVAP canister ports. Apply vacuum. If vacuum holds, go to step  22. If vacuum does not hold, replace EVAP canister. After replacing EVAP canister, go to step  22.
  12. Using vacuum pump, check hoses "H" through "K" for leaks. Replace hose(s) as necessary. After repairs, go to step  22. If problem does not exist, go to next step.
  13. Remove fuel tank. Using vacuum pump, check hoses "L" through "N" for leaks. See Figure and Figure . Replace hose(s) as necessary. Install fuel tank. After repairs, go to step  22. If problem does not exist, go to next step.
  14. Visually check for cracks and leaks in fuel tank. Connect EVAP system pressure tester to return pipe port. See Figure. Securely plug all fuel tank openings. Using EVAP system pressure tester, apply pressure. Using soapy water, check each section of fuel tank for leaks. Repair as necessary. After repairs, go to step  22. If no leaks are found, go to next step.
  15. Visually check for cracks in fuel filler neck. Replace fuel filler neck as necessary. Reinstall fuel tank. After repairs, go to step  22. If problem does not exist, reinstall fuel tank. After repairs, go to step  22.
  16. Lower EVAP canister assembly, located at left rear of vehicle. Disconnect hose "G" from ventilation solenoid. See Figure. On EVAP system pressure pump, set pressure/hold valve to OPEN and set vent valve to CLOSED. Turn pump timer on. Air should pass through hose "G". If air passes through hose "G", go to step  19. If air does not pass through hose "G", go to next step.
  17. Using vacuum pump, check hose "I" for clogging. See Figure. Replace hose as necessary. After repairs, go to step  24. If problem does not exist, go to next step.
  18. Remove fuel tank. Using vacuum pump, check hoses "L" through "N" for clogging. See Figure. Replace hose(s) as necessary. Reinstall fuel tank. After repairs, go to step  24. If problem does not exist, reinstall fuel tank. After repairs, go to step  20.
  19. Lower EVAP canister assembly located at left rear of vehicle. Disconnect hose "F" from EVAP canister. Connect vacuum pump to hose "F". Apply 12 in. Hg (40 kPa) or less vacuum. Using scan tool, select actuator test No. 8 (purge solenoid). Vacuum should leak when purge solenoid is actuated. If vacuum does not hold, go to step  24. If vacuum holds, go to next step.
  20. Using vacuum pump, check hoses "C" through "G" for clogging. Replace hose(s) as necessary. After repairs, go to step  24. If problem does not exist, go to next step.
  21. Remove hoses from EVAP canister. Connect vacuum pump to EVAP canister port from which hose "G" was disconnected. Plug other 2 EVAP canister ports. Apply vacuum. Then unplug each port in turn. Each port should leak vacuum. If vacuum holds, replace EVAP canister. After replacing EVAP canister, go to step  24. If vacuum does not hold, go to next step.
  22. Ensure fuel cap is tightened 3 clicks. Turn ignition on. Using scan tool, clear DTCs. Start engine. Start EVAP system leak monitor test. Using MUT-II scan tool, select SYSTEM TEST and press YES key. Select EVAP LEAK MON and press YES key. During monitor, keep accelerator pedal in idling position. Item IN PROGRESS is displayed during monitor. IN PROGRESS will change from NO to YES by keeping engine speed and load within defined range. Go to next step.
    NOTE: If engine speed does not reach 2000 RPM during monitor, adjustment of fixed Speed Adjusting Screw (SAS) may be needed. See FIXED SPEED ADJUSTING SCREW under IDLE SPEED & MIXTURE in ON-VEHICLE ADJUSTMENTS article.
  23. If EVAP LEAK MON. COMPLETED. TEST PASSED is then displayed, EVAP system currently is working properly. DTC was probably set by an improperly installed fuel cap. If EVAP LEAK MON. COMPLETED. TEST FAILED & DTCS SET is displayed, go to step  2. If EVAP LEAK MON. DISCONTINUED. RETEST AGAIN FROM THE FIRST is displayed, turn off ignition, and repeat monitor. Go to step  22.
  24. Using scan tool, clear DTCs. Test drive vehicle following EVAP system leak monitor drive cycle pattern. See OBD-II DRIVE CYCLES under VERIFYING REPAIRS . Check for DTCs. Confirm DTC does not reset. See VERIFYING REPAIRS .
Fig 1: Locating Hose "A"
G99F54184Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
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