LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mitsubishi >> 2003 >> Eclipse RS, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.4L >> Diagnostic Tests >> DTC P0455: EVAP System Large Leak Detected >> Diagnostic Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedure

CAUTION: To prevent damage to scan tool (MB991502), always turn the ignition off before connecting or disconnecting it.
CAUTION: With this monitor, the ECM (M/T) or PCM (A/T) automatically increases the engine speed to 1,600 RPM or more. Check that the transaxle is set to "neutral" (M/T) or "P" (A/T) position.
  1. Connect scan tool (MB991502) to the data link connector. Turn the ignition on. Erase the DTCs using the scan tool. Check that the fuel cap is securely closed (tighten until three clicks are heard). Start the engine. Select "System Test" and press the "YES" key. Select "Evap Leak Mon" and press the "YES" key. During the monitor, keep the accelerator pedal at the idling position. If the engine speed odes not reach 2000 RPM during the monitor test, adjustment of the Speed Adjusting Screw may be needed. Keep the engine speed and engine load within the specified range. When the monitor test starts, the "In Progress" item on scan tool (MB991502) will change from "NO" to "YES". If the scan tool shows: "Evap Leak Mon. Completed. Test Passed", the evaporative emission system is working properly at this time. Explain to the customer that improperly tightened fuel cap can cause MIL to turn on, and return the vehicle. If the scan tool shows: "Evap Leak Mon. Completed. Test Failed and DTCs Set", a malfunction has been detected during the monitor test, go to the next step. If the scan tool shows: "Evap Leak Mon. Discontinued. Retest again from the first", the monitor was discontinued for some reason (vehicle speed input from computer, engine speed and engine load deviating from specified range). Turn the ignition off once and repeat the monitoring starting with step  1 .
  2. Disconnect hoses "A" and "B" from the evaporative emission purge solenoid side, and connect the hand vacuum pump to the evaporative emission purge solenoid instead of hose "B". Turn the ignition on. Set scan tool (MB991502) to actuator test mode for item 08, Evaporative Emission Purge Solenoid. When the evaporative emission purge solenoid is operated, apply a pressure on the hand vacuum pump and confirm that air is blown from the other side nipple. Turn the ignition off and disconnect the scan tool. Disconnect the hand vacuum pump, and connect hoses "A" and "B" to the evaporative emission purge solenoid. If the solenoid is in good condition, go to the next step. If the solenoid is damaged, replace the evaporative emission purge solenoid and proceed to step  27 .
  3. Check for leaks and clogging in the evaporator line hose "A" to hose "C". If the hoses are in good condition, go to the next step. If the hoses are damaged, replace the inferior hose(s) and proceed to step  27 .
  4. Check for leaks and clogging in the chamber. The chamber should naturally restrict air flow, air leakage from the chamber body is normal. If the chamber is in good condition, go to the next step. If the chamber is damaged, replace it and proceed to step  27 .
  5. Connect scan tool (MB991502) to the data link connector. Disconnect hose "E" from the evaporative emission ventilation solenoid side, and connect a hand vacuum pump. Turn the ignition on. Set the scan tool to actuator test mode for item 29, Evaporative Emission Ventilation Solenoid. When the evaporative emission ventilation solenoid is operated, apply a pressure on the hand vacuum pump and confirm that air is maintained. Turn the ignition off and disconnect the scan tool. Disconnect the hand vacuum pump, and connect hose "E" to the evaporative emission canister. If the solenoid valve is in good condition, go to the next step. If the solenoid valve is damaged, replace the evaporative emission ventilation solenoid and proceed to step  27 .
  6. Pressure test for leaks in the evaporator line from hose "D" to hose "N". Disconnect hose "E" from the evaporative emission ventilation solenoid side, and plug the hoses. Remove the fuel cap. Connect the evaporative emission system pressure pump to the fuel filler neck. Apply a pressure on the evaporative emission system pressure pump, and confirm that air is maintained. Note that "Pressure test" in this procedure refers to the I/M240 Simulation Test (8 simple steps) described in the evaporative emission system pressure pump (Miller number 6872A) manufacturer's instructions located in the lid of the pump box. Disconnect the evaporative emission system pressure pump, and reinstall the fuel cap. Connect hose "E" to the evaporator line. If air is maintained, proceed to step  17 , otherwise, go to the next step.
  7. Pressure test for leaks in the evaporator line from hose "G" to hose "N". Disconnect hose "G" from the evaporative emission canister side, and plug the hose. Perform the pressure test again. If air is maintained, proceed to step  10 , otherwise, go to the next step.
  8. Check for leaks in the evaporator line from hose "D" to hose "F". Remove the fuel tank. The leakage test with a hand vacuum pump on each hose from hose "D" to hose "F". If the hoses are in good condition, go to the next step. If the hoses are damaged, replace the inferior hose, reinstall the fuel tank and proceed to step  27 .
  9. Check for leaks in the evaporative emission canister. Connect a hand vacuum pump to the vent nipple of the evaporative emission canister. Plug the other two nipples or loop a hose between the other nipples. Apply a vacuum with the hand vacuum pump, and confirm that air is maintained. If the evaporative emission canister is damaged, replace it and reinstall the fuel tank. Proceed to step  27 .
  10. Check for leaks in the evaporator line from hose "H" to hose "I". Remove the fuel tank. Disconnect hose "H" at the liquid separator side, and then connect a hand vacuum pump to the hose. Plug hose "I" at the fuel tank side. Apply vacuum by using the hand vacuum pump, and confirm that the applied vacuum does not fluctuate. If air is maintained, go to the next step. If air leaks, replace the inferior hose, reinstall the fuel tank and proceed to step  27 .
  11. Check for leaks in the evaporator line hose "G", "J", "K", "L" and hose "M". Remove the filler neck assembly. The leakage test with a hand vacuum pump on each hose from hoses "G", "J", "K", "L" and "M". If the hoses are in good condition, go to the next step. If the hoses are damaged, replace the inferior hose, reinstall the filler neck assembly and proceed to step  27 .
  12. Check the check valve "A". The check valve should only allow air to pass in one direction. It is normal for air to leak from the check valve body as it passes air. If check valve "A" is in good condition, go to the next step. If the check valve is damaged, replace the check valve "A", reinstall the filler neck assembly and proceed to step  27 .
  13. Check the check valve "B". The check valve should allow more air to pass in one direction, than the other. Verify this. It is normal for air to leak from the check valve body as it passes air. If check valve "B" is in good condition, go to the next step. If the check valve is damaged, replace it, reinstall the filler neck assembly and proceed to step  27 .
  14. Check for leaks in the evaporator line from hose "N". The leakage test with a hand vacuum pump on the hose "N". If hose "N" is in good condition, go to the next step. If the hose is damaged, replace it, reinstall the fuel tank and proceed to step  27 .
  15. Check for leaks in the fuel tank. Carefully check the fuel pump assembly and the inner pressure sensor installation section in the fuel tank. Connect an evaporative emission system pressure pump to the leveling valve nipple. Plug the filler hose, feed pipe, return pipe and rollover valve nipple connected to the fuel tank. If these items are not securely plugged here, the fuel could leak in the next step. Apply pressure with the evaporative emission system pressure pump. In the pressurized state, check for the leak by applying soap water or the like to each section. If there are any leaks at the fuel pump module or the fuel tank differential pressure sensor section: Reassemble the leaking parts, check again for leaks, reinstall the fuel tank and proceed to step  27 . If there are any leaks at the fuel tank: Replace the fuel tank and reinstall it, then proceed to step  27 . If there are no leaks, go to the next step.
  16. Visually check for cracks in the fuel tank filler neck. If the fuel filler neck assembly is in good condition, reinstall the fuel tank and fuel filler neck assembly. If the fuel filler neck assembly is damaged, replace the fuel tank filler neck assembly and reinstall the fuel tank. Proceed to step  27 .
  17. Pressure test for clogging in the evaporator line from hose "G" to hose "N". Disconnect hose "G" from the evaporative emission canister side, and unplug hose "G". On the EVAP pressure pump, set the pressure/hold valve to OPEN, and set the vent valve to CLOSED. Turn the pump timer ON. You can reset the timer as required. (These settings are listed under "Leak Test" in the pump instructions.) Air should pass through hose "G". If air is blown from hose "G", connect the hose and go to the next step. If no air is blown, proceed to step  22 .
  18. Pressure test for clogging in the evaporator line from hose "D" to hose "F". Unplug hose "E". On the EVAP pressure pump, set the pressure/hold valve to OPEN, and set the vent valve to CLOSED. Turn the pump timer to ON. You can reset the timer as required. (These settings are listed under "Leak Test" in the pump instructions.) Air should pass through hose "E". If air is blown from hose "E", connect the hose and go to the next step. If air is not blown, proceed to step  20 .
    19. CAUTION: With this monitor, the ECM (M/T) or PCM (A/T) automatically increases the engine speed to 1,600 RPM or more. Check that the transaxle is set to "neutral" (M/T) or "P" (A/T) position.
  19. Connect scan tool (MB991502) to the data link connector. Turn the ignition on. Erase the DTCs with the scan tool. Check that the fuel cap is securely closed. (Tighten until three clicks are heard.) Start the engine. Select "System Test" and press the "YES" key. Select "Evap Leak Mon" and press the "YES" key. During the monitor, keep the accelerator pedal at the idling position. If the engine speed does not reach 2000 RPM during the monitor test, adjustment of the Speed Adjusting Screw may be needed. Keep the engine speed and engine load within the specified range. When the monitor test starts, the "In Progress" item on the scan tool will change from "NO" to "YES". Turn the ignition off and disconnect the scan tool. If the scan tool shows "Evap Leak Mon. Completed. Test Passed": The evaporative emission system is working properly at this time, proceed to step  27 . If the scan tool shows "Evap Leak Mon. Completed. Test Failed and DTCs Set": Replace the ECM (M/T) or PCM (A/T) and proceed to step  27 . If the scan tool shows "Evap Leak Mon. Discontinued. Retest again from the first": The monitor was discontinued for some reason (vehicle speed input from ECM (M/T) or PCM (A/T), engine speed and engine load deviating from specified range). Turn the ignition off once, and recheck the evaporative emission system monitor test.
  20. Check for clogging in the evaporator line hose "D" to hose "F". Remove the fuel tank. The clogging test with a hand vacuum pump on each hose from "D" to "F". If the hoses are in good condition, go to the next step. If the hoses are damaged, replace the inferior hose, reinstall the fuel tank and proceed to step  27 .
  21. Check for clogging in the evaporative emission canister. Connect a hand vacuum pump to the vent nipple of the evaporative emission canister. Plug the other two nipples or loop a hose between the other nipples. Apply a pressure on the vacuum pump. When each nipple is unplugged, air should pass through the unplugged nipple. If the evaporative emission canister is in good condition, reinstall the fuel tank. If the evaporative emission canister is damaged, replace it and reinstall the fuel tank. Proceed to step  27 .
  22. Check for clogging in the evaporator line from hose "H" to hose "I". Remove the fuel tank. Disconnect hose "H" at the liquid separator side, and then connect a hand vacuum pump to the hose. Unplug the hose "I" at the fuel tank side. Apply a pressure on the vacuum pump, air should pass through hose "I". If the hoses are in good condition, go to the next step. If the hoses are damaged, replace the inferior hose, reinstall the fuel tank and proceed to step  27 .
  23. Check for clogging in the evaporator line hose "G", "J", "K", "L" and hose "M". Remove the filler neck assembly. The clogging test with a hand vacuum pump on each hose from hoses "G", "J", "K", "L" and "M". If the hoses are in good condition, go to the next step. If the hoses are damaged, replace the inferior hose, reinstall the filler neck assembly and proceed to step  27 .
  24. Check the check valve "A". The valve should only allow air to pass in one direction. It is normal for air to leak from the check valve body. If check valve "A" is in good condition, go to the next step. If the check valve is damaged, replace it, reinstall the filler neck assembly and proceed to step  27 .
  25. Check the check valve "B". The valve should allow more air to pass in one direction than the other. Verify this. It is normal for air to leak from the check valve body. If check valve "B" is in good condition, go to the next step. If check valve B is damaged, replace it, reinstall the filler neck assembly and proceed to step  27 .
  26. Check for clogging in the evaporator line from hose "N". The clogging test with a hand vacuum pump on hose "N". If hose "N" is in good condition, go to the next step. If the hose is damaged, replace it, reinstall the fuel tank and go to the next step.
  27. Carry out a test drive with the drive cycle pattern, refer to EVAP SYSTEM LEAK MONITOR  . Read the diagnostic trouble codes. If DTC P0455 is set, retry the troubleshooting from step  1 . If the DTC is absent, the diagnosis is complete.
scientia non olet · About LEMON Manuals