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Home >> Mitsubishi >> 2002 >> Montero XLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0455: EVAP Emission Control System Large Leak Detected >> Test Procedure
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Test 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. Ensure transaxle is in Park and fuel cap is securely tightened (3 clicks). 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. 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 next step. If EVAP LEAK MON. DISCONTINUED is displayed, turn ignition off and start monitor over.
    NOTE: Monitor test will automatically increase engine speed. If engine speed does not reach 1600 RPM or more 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.
  2. Disconnect hoses "A" and "B" at purge solenoid side. See Figure, Figure and Figure . Connect hand pressure/vacuum pump to purge solenoid port from which hose "B" was disconnected. Turn ignition on. Using scan tool, select actuator test item No. 8 (purge solenoid). When purge solenoid is actuated, using hand pressure/vacuum pump, apply pressure. Verify pressure blows through the other port. If pressure blows through, go to next step. If pressure does not blow through, replace purge solenoid valve. Then go to step  20.
  3. Thoroughly check hoses "A", "B" & "C" for damage, clogging or leaks. If the hoses are OK, go to next step. If hoses are damaged, replace as necessary. Go to step  20
  4. Disconnect hose "T" at ventilation solenoid side. See Figure and Figure . Connect hand pressure/vacuum pump to ventilation solenoid port from which hose "T" was disconnected. Turn ignition on. Using scan tool, select actuator test item No. 29 (ventilation solenoid). When ventilation solenoid is actuated, using hand pressure/vacuum pump, apply pressure. Verify pressure is held. If pressure is held, go to next step. If pressure is not held, replace ventilation solenoid valve. Then go to step  20.
  5. Thoroughly check hose "T" for damage, clogging or leaks. If the hose is OK, go to next step. If hose is damaged, replace as necessary. Go to step  20.
  6. Thoroughly check hose "F" for damage, clogging or leaks. See Figure and Figure . If the hose is OK, go to next step. If hose is damaged, replace as necessary. Go to step  20.
  7. Confirm Miller EVAP System Pressure Pump (6872A) is operating properly. Perform self-test as described by manufacturer. Pressure test for leaks in the EVAP system between hose "G" to hose "S". Remove fuel cap. Disconnect hose "G" from EVAP canister side and plug. 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, connect hose "G" to EVAP canister and go to next step. If leak is not indicated, go to step  15.
  8. Remove the fuel tank filler neck protector. Disconnect hose "H" from EVAP canister side and connect a hand pressure/vacuum pump. See Figure and Figure . Pressurize hose "G" and verify pressure is maintained. If leak is not indicated, go to next step. If leak is indicated, replace defective hose, reinstall filler neck protector and go to step  20.
  9. Thoroughly check hoses "H", "I", "J", "K", "L" M", "N" and "O" for damage clogging or leaks. If the hoses are not damaged or clogged, go to next step. If hoses are damaged so clogged, replace as necessary. Go to step  20.
  10. Inspect check valve "A". See Figure,Figure and Figure . Only when air is blown through the valve in the direction shown in the figure, should it pass air. If the valve is good, go to next step. If the valve is bad, replace valve, reinstall filler neck protector and go to step  20.
  11. Inspect check valve "B". See Figure, Figure and Figure . When air is blown through the valve in the direction shown in the top of figure, should it pass more air as compared to when air blown through valve in the direction shown in the bottom of figure. If the valve is good, go to next step. If the valve is bad, replace valve, reinstall filler neck protector and go to step  20.
  12. Remove fuel tank. Using hand vacuum pump, check hoses "P" and "S" for leaks. See Figure and Figure . If leak is indicated, replace appropriate hose, install fuel tank. Go to step  20. If leak does not exist, go to next step.
  13. Visually check fuel tank for cracks and leaks. Connect EVAP system pressure pump to fuel return hose. See . 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. If leak exists, repair leak, install fuel tank and fuel filler neck protector. Go to step  20. If leak does not exist, install fuel tank and fuel filler neck protector. Go to next step.
  14. Ensure transaxle is in Park and fuel cap is securely tightened (3 clicks). Start engine and let idle. 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. 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. Go to step  20. If EVAP LEAK MON. COMPLETED. TEST FAILED & DTCS SET is displayed, replace PCM and go to step  20. If EVAP LEAK MON. DISCONTINUED is displayed, turn ignition off and start monitor over.
  15. Confirm Miller EVAP System Pressure Pump (6872A) is operating properly. Perform self-test as described by manufacturer. Pressure test and check for clogging in the EVAP system between hose "G" to hose "S". Remove fuel cap. Disconnect hose "G" from EVAP canister and plug. 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. After verifying pressure is maintained, unplug hose "G" and verify air is blown from hose. If clogging is indicated, go to next step. If leak is not indicated, go to step  20.
  16. Remove the fuel tank filler neck protector. Disconnect hose "H" from EVAP canister side and connect a hand pressure/vacuum pump. Pressurize hose "G" and verify pressure is maintained. If leak is not indicated, go to next step. If leak is indicated, replace defective hose, reinstall hose "H", filler neck protector and go to step  20.
  17. Thoroughly check hoses "H", "I", "J", "K", "L" M", "N" and "O" for damage clogging or leaks. If the hoses are not damaged or clogged, go to next step. If hoses are damaged so clogged, replace as necessary. Go to step  20.
  18. Remove fuel tank assembly. Using hand vacuum pump, check hoses "D" to "E" for leaks or clogging. If leaks or clogging is indicated, replace appropriate hose, install fuel tank assembly. Go to step  20. If leak is not indicated, go to next step.
  19. Remove EVAP canister. Connect hand vacuum pump to canister directly. Plug the other 2 nipples. Apply pressure on the hand pressure/vacuum pump, and confirm the pressure is held. If the pressure is held, go to step  14. If pressure is not held, replace EVAP canister and go to next step.
  20. 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, go to step  1 and retry diagnostic procedure. If DTC P0455 is not output, inspection is complete.
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