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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 68 (Engine Controls Self-Diagnostics - Pathfinder & QX4) >> Diagnostic Tests >> DTC P1448: EVAP Canister Vent Control Valve - Stuck Open >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Pathfinder and 2002 Infiniti QX4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off. Disconnect hose from EVAP-CVCV. See Figure . Check hose for blockage. If blockage exists, clean hose with compressed air. If blockage does not exist, go to next step.
  2. Remove EVAP-CVCV. Check for rust in port "B". See Figure . If rust does not exist, go to next step. If rust exists, replace EVAP-CVCV. After repair, repeat appropriate DTC confirmation test.
  3. If using CONSULT-II, go to next step. If using generic scan tool, go to step  5 .
  4. Reconnect all harness connectors. Turn ignition on. Perform VENT CONTROL/V in ACTIVE TEST mode with CONSULT-II. When VENT CONTROL/V is ON, air should not flow between ports "A" and "B". When VENT CONTROL/V is OFF, air should flow between ports "A" and "B". It should take less than one second for valve to open or close. If operation is as specified, go to step  6 . If operation is not as specified, clean EVAP-CVCV with compressed air, and retest. If operation is still not as specified, replace EVAP-CVCV. After repair, repeat appropriate DTC confirmation test.
  5. Using jumper wires, apply battery voltage to EVAP-CVCV terminals. See Figure . With voltage applied, air should not flow between ports "A" and "B". Remove jumper wires. Air should flow. EVAP-CVCV should switch in less than one second. If operation is as specified, go to next step. If operation is not as specified, clean EVAP-CVCV with compressed air, and retest. If operation is still not as specified, replace EVAP-CVCV. After repair, repeat appropriate DTC confirmation test.
  6. Turn ignition off. Remove vacuum cut valve. See Figure . Plug ports "C" and "D". See Fig 1 . Using a hand vacuum pump, apply vacuum to port "A". Vacuum should not exist at port "B". Apply vacuum to port "B". Vacuum should exist at port "A". Blow air into port "B". Air should flow out of port "A" with some resistance. Unplug ports "C" and "D". Blow air into port "A". Air should flow freely out of port "C". Blow air into port "B". Air should flow freely out of port "D". If operation is as specified, go to next step. If operation is not as specified, replace vacuum cut valve. After repair, repeat appropriate DTC confirmation test.
  7. Remove EVAP canister with EVAP-CVCV attached. Invert EVAP canister and 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, go to step  9 .
  8. Weigh EVAP canister with EVAP-CVCV attached. If EVAP canister weighs less than 4.0 lbs. (1.8 kg), go to next step. If EVAP canister weighs 4.0 lbs. (1.8 kg) or more, inspect EVAP canister for damage and hoses to water separator for poor connections or blockage. If problem is found, repair or replace as necessary. After repair, repeat appropriate DTC confirmation test.
  9. Check for disconnection or improper connection of hose connected to EVAP-CSPS. If a problem is found, repair as necessary. If no problem is found, disconnect EVAP-CSPS 2-pin harness connector. Check for water damage to connector and terminals. If water damage does not exist in connector, go to next step. If water damage exists in connector, replace EVAP-CSPS. After repair, repeat appropriate DTC confirmation test.
    10. CAUTION: DO NOT apply more than 5.91 in. Hg (20 kPa) of vacuum 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.
  10. 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 test.
  11. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Identifying Vacuum Cut Valve Ports
G99B54834Courtesy of NISSAN MOTOR CO., U.S.A.
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