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Home › Infiniti › 2003 › QX4 4WD › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0442: EVAP Control System - Small Leak Detected › Diagnostic Procedure

Diagnostic Procedure

  1. Ensure fuel cap is original equipment. Check for genuine NISSAN fuel cap design. If fuel cap is genuine, go to next step. If fuel cap is not genuine, replace with appropriate replacement part. After repair, repeat appropriate DTC confirmation procedure.
  2. Verify that fuel cap is tightened properly. Attempt to turn fuel cap clockwise. If fuel cap was tightened properly, go to next step. If fuel cap was not tightened properly, clean fuel cap and filler neck with compressed air. Reinstall cap and retest system. After repair, repeat appropriate DTC confirmation procedure.
  3. While removing fuel cap, listen for air escaping from fuel tank. If air escaped from fuel tank, go to step  5. If air did not escape from fuel tank, go to next step.
  4. Using a suitable hand vacuum/pressure pump with Fuel Filler Cap Adapter (MLR-8382), apply pressure and vacuum to fuel cap. Fuel cap vacuum relief valve should open when pressure reaches 2.22-2.90 psi (15.3-20.0 kPa) and when vacuum reaches .98-1.78 in. Hg (3.3-6.0 kPa). If operation is as specified, go to next step. If operation is not as specified, replace fuel cap. After repair, repeat appropriate DTC confirmation procedure.
  5. Connect EVAP Service Port Adapter (J41413-OBD) to EVAP service port. See Figure. Connect a suitable pressure pump to adapter. DO NOT use compressed air. If using CONSULT-II, go to next step. If using generic scan tool, go to step  7.
  6. Turn ignition on. Select EVAP SYSTEM CLOSE of WORK SUPPORT mode with CONSULT-II. Press START. Observe pressure indicator on CONSULT-II. Apply pressure to EVAP system until pressure indicator reaches middle of bar graph. DO NOT exceed .6 psi (4.12 kPa) of pressure. Using Leak Detector (J41416), locate EVAP leak. See VACUUM DIAGRAMS article. If a leak is found, repair as necessary. After repair, repeat appropriate DTC confirmation procedure. If no leak is found, go to step  8.
  7. Turn ignition off. Disconnect EVAP Canister Vent Control Valve (EVAP-CVCV) and EVAP vacuum cut valve by-pass valve 2-pin harness connectors. Using jumper wires, apply battery voltage and ground to EVAP-CVCV and vacuum cut valve by-pass valve terminals (component side). See Fig 1. Apply .2-.4 psi (1.38-2.76 kPa) of pressure to EVAP service port. DO NOT exceed .6 psi (4.12 kPa) of pressure. Remove pressure pump from EVAP service port. Using Leak Detector (J41416), locate EVAP system leak. See VACUUM DIAGRAMS article. If no leak is found, go to next step. If a leak is found, repair as necessary. After repair, repeat appropriate DTC confirmation procedure.
    8. CAUTION: DO NOT disassemble water separator.
  8. Remove water separator and inspect for cracks or blockage. With water separator port "A" plugged, blow air into port "B". See Fig 2. Air should flow out of port "C". With port "C" plugged, blow air into port "B". Air should flow out of port "A". If operation is as specified, go to next step. If operation is not as specified, replace water separator. After repair, repeat appropriate DTC confirmation procedure.
  9. Check EVAP-CVCV, "O" ring and circuit. Perform DTC CONFIRMATION TEST  under DTC P1446: EVAP CANISTER VENT CONTROL VALVE. If 1st trip DTC is not detected, go to next step. If 1st trip DTC is detected, repair as necessary. After repair, repeat appropriate DTC confirmation procedure.
  10. Remove EVAP canister with EVAP-CVCV attached. Attempt to drain water from EVAP canister. If water drains from EVAP canister, go to next step. If water does not drain from EVAP canister and CONSULT-II is available, go to step  13. If water does not drain from EVAP canister, and CONSULT-II is not available, go to step  14.
  11. Weigh EVAP canister with EVAP-CVCV attached. If weight is more than 4.0 lbs. (1.8 kg), go to next step. If weight is less than 4.0 lbs. (1.8 kg) and CONSULT-II is available, go to step  13. If weight is less than 4.0 lbs. (1.8 kg) and CONSULT-II is not available, go to step  14.
  12. Inspect EVAP canister for damage. Also, check hose between water separator and EVAP canister for blockage or poor connection. Repair as necessary. After repair, repeat appropriate DTC confirmation procedure.
  13. Disconnect EVAP-CPVCSV hose at EVAP service port. Start engine. Perform PURG VOL CONT/V in ACTIVE TEST mode with CONSULT-II. Press Qu on CONSULT-II screen to increase PURG VOL CONT/V opening to 100 percent. Check for vacuum at disconnected hose while increasing engine speed to 2000 RPM. If vacuum exists, go to step  16. If vacuum does not exist, go to step  15.
  14. Start engine and warm to normal operating temperature. Turn ignition off. Disconnect EVAP-CPVCSV hose at EVAP service port. Start engine and let it idle for at least 80 seconds. While quickly increasing engine speed to 2000 RPM, check for vacuum at EVAP-CPVCSV hose. If vacuum does not exist, go to next step. If vacuum exists, go to step  17.
  15. Check EVAP system vacuum hoses for blockages or leaks. See VACUUM DIAGRAMS article. If no problem is found and CONSULT-II is available, go to next step. If no problem is found and CONSULT-II is not available, go to step  17. If problem is found, repair as necessary. After repair, repeat appropriate DTC confirmation procedure.
  16. Start engine. Perform PURG VOL CONT/V in ACTIVE TEST mode with CONSULT-II. Engine speed should vary according to valve opening. If operation is as specified, go to step  18. If operation is not as specified, go to next step.
  17. Turn ignition off. Remove vacuum hoses from EVAP-CPVCSV. Perform PURG VOL CONT/V in ACTIVE TEST mode with CONSULT-II. With PURG VOL CONT/V at 100 percent, air should flow between ports "A" and "B". With PURG VOL CONT/V at zero percent, air should not flow between ports "A" and "B". Using generic scan tool, perform following. Disconnect EVAP-CPVCSV 2-pin harness connector. Using jumper wires, apply battery voltage and ground to EVAP-CPVCSV terminals. Air should flow between ports "A" and "B". See Figure. Remove jumper wires. Air should not flow. If operation is as specified, go to next step. If operation is not as specified, replace EVAP-CPVCSV. After repair, repeat appropriate DTC confirmation procedure.
  18. Remove fuel level sensor/fuel pump assembly. Access cover is located under rear seat. See FUEL LEVEL SENSOR under FUEL SYSTEMS in REMOVAL & INSTALLATION article. Separate Fuel Tank Temperature (FTT) sensor from assembly. Measure resistance between FTT pigtail connector terminals No. 1 and 2, with FTT sensor submerged in heated water. See Figure. Resistance should be within acceptable range shown. See Figure. If resistance is as specified, go to next step. If resistance is not as specified, replace FTT sensor. After repair, repeat appropriate DTC confirmation procedure.
    19. CAUTION: DO NOT apply more than 5.91 in. Hg (20 kPa) of vacuum or more then 2.9 psi (20 kPa) of pressure to EVAP-CSPS. Replace EVAP-CSPS if it has been dropped from a height of more than 20" (.5 m) onto a hard surface such as concrete.
    CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  19. Remove EVAP Control System Pressure Sensor (EVAP-CSPS) with its harness connector connected. See Figure. Turn ignition on. Using a hand vacuum pump, apply 2.76 in. Hg (9.3 kPa) of vacuum to EVAP-CSPS. Backprobbing at ECM, measure voltage between ground and ECM terminal No. 84 (Blue/Green wire). See Figure and Figure . With 2.76 in. Hg (9.3 kPa) of vacuum applied to EVAP-CSPS, voltage should be .4-.6 volt. When vacuum is removed, voltage should be 3.0-3.6 volts. If voltage is as specified, go to next step. If voltage is not as specified, replace EVAP-CSPS. After repair, repeat appropriate DTC confirmation procedure.
  20. Check EVAP purge line at fuel tank and EVAP canister for leaks or improper connection. See VACUUM DIAGRAMS article. If a problem is found, repair as necessary. After repair, repeat appropriate DTC confirmation procedure. If purge line is okay, clean with compressed air, then go to next step.
  21. Check refueling EVAP vapor line between EVAP canister and fuel tank for clogging, kink, looseness or improper connection. See VACUUM DIAGRAMS article. If no problem is found, go to next step. If problem is found, repair or replace hoses or tubes as necessary. After repair, repeat appropriate DTC confirmation procedure.
  22. Check signal line and recirculation line between filler neck and fuel tank for clogging, kink, cracks, looseness and improper connection. If no problem is found, go to next step. If problem is found, repair or replace hoses, tubes or filler neck as necessary. After repair, repeat appropriate DTC confirmation procedure.
  23. Check refueling control valve. For testing procedure, see FUEL EVAPORATIVE SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. If refueling control valve is okay, go to next step. If refueling control valve is not okay, replace fuel tank. After repair, repeat appropriate DTC confirmation procedure.
  24. Check fuel level sensor/pump. For testing procedure, see FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If no problem is found, go to next step. If problem is found, replace fuel level sensor. After repair, repeat appropriate DTC confirmation procedure.
  25. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Checking EVAP System For Leak
G00103809Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Testing Water Separator
G99H54806Courtesy of NISSAN MOTOR CO., U.S.A.
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