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Home >> Infiniti >> 2002 >> Q45 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - Q45 >> Diagnostic Tests >> DTC P0450: EVAP Control System Pressure Sensor >> Diagnostic Procedure

Diagnostic Procedure

  1. Check EVAP-CSPS hose for clogging, leak, kink, disconnection or improper connection. See Figure. If problem is found, repair as necessary. If problem is not found, loosen and retighten engine ground bolts. See Figure. Disconnect EVAP-CSPS harness connector. If water exists in connector, repair or replace connector. If water does not exist, go to next step.
  2. Turn ignition on. Measure voltage between ground and EVAP-CSPS harness connector terminal No. 1 (Blue wire). If voltage is about 5 volts, go to step  4. If voltage is not about 5 volts, go to next step.
  3. Check the following:
    • Check for poor connection at Light Blue, 8-pin in-line harness connector B401 terminal No. 8 (Blue wire). See Figure. Connector B401 is located under rear of vehicle, near EVAP-CVCV.
    • Check for poor connection at Super Multiple Junction harness connector M141 terminal 58V (Yellow wire). See Figure and Figure .
    • Check for poor connection at Super Multiple Junction harness connector F105 terminal 23T (Blue wire). See Figure and Figure .
    • Check for open or short between EVAP-CSPS and ECM.

    Repair as necessary.

  4. Turn ignition off. Check continuity between ground and EVAP-CSPS harness connector terminal No. 3 (Red wire). Continuity should exist. Also, check circuit for short to voltage. If a problem is found, go to next step. If circuit is okay, go to step  6.
  5. Check the following:
    • Check for poor connection at Light Blue, 8-pin in-line harness connector B401 terminal No. 7 (Red wire). See Figure. Connector B401 is located under rear of vehicle, near EVAP-CVCV.
    • Check for poor connection at Super Multiple Junction harness connector M141 terminal 56V (Red wire). See Figure and Figure .
    • Check for poor connection at Super Multiple Junction harness connector F105 terminal 10T (Red wire). See Figure and Figure .
    • Joint connector No. 30 (connector F108). See Figure and Figure .
    • Check for open or short between EVAP-CSPS and ECM.

    Repair as necessary.

  6. Disconnect ECM harness connector. See Figure. Check continuity of Green wire between EVAP-CSPS harness connector terminal No. 2 and ECM harness connector terminal No. 110. See Figure. Also, check circuit for short to ground and short to voltage. If problem is found, go to next step. If circuit is okay, go to step  8.
  7. Check the following:
    • Check for poor connection at Light Blue, 8-pin in-line harness connector B401 terminal No. 6 (Green wire). See Figure. Connector B401 is located under rear of vehicle, near EVAP-CVCV.
    • Check for poor connection at Super Multiple Junction harness connector M141 terminal 55V (Green wire). See Figure and Figure .
    • Check for poor connection at Super Multiple Junction harness connector F105 terminal 9T (Green wire). See Figure and Figure .
    • Check for open or short between EVAP-CSPS and ECM.

    Repair as necessary.

  8. If using CONSULT-II, go to next step. If using generic scan tool, go to step  11.
  9. 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  12. If operation is not as specified, go to next step.
  10. Disconnect hoses from EVAP-CPVCV. See Figure. Command PURG VOL CONT/V to 100 percent with CONSULT-II. Air should flow between EVAP-CPVCV ports "A" and "B". Command PURG VOL CONT/V to zero percent. Air should not flow between EVAP-CPVCV ports "A" and "B". If operation is as specified, go to step  12. If operation is not as specified, replace EVAP-CPVCV.
  11. Remove EVAP-CPVCV. See Figure. Using jumper wires, apply battery voltage to EVAP-CPVCV terminals. See Figure. Air should flow between ports "A" and "B". Remove jumper wires. Air should not flow. If operation is as specified, go to next step. If operation is not as specified, replace EVAP-CPVCV.
  12. Disconnect hose from EVAP-CVCV. See Figure. Check hose for clogging. If hose is okay, go to next step. If hose is not okay, clean with compressed air.
  13. Remove EVAP-CVCV. Check for rust in port "B". See Figure. If rust exists, replace EVAP-CVCV. If rust does not exist, go to next step.
  14. If using CONSULT-II, go to next step. If using generic scan tool, go to step  16.
  15. 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  17. If operation is not as specified, clean EVAP-CVCV with compressed air, and retest. If operation is still not as specified, replace EVAP-CVCV.
  16. Using jumper wires, apply battery voltage to EVAP-CVCV terminals. See Figure. 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.
    17. 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.
  17. Remove 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. Measure voltage between ground and ECM terminal No. 110 (Green wire) by backprobing. See Figure and Figure . Voltage should be .4-.6 volt. Disconnect vacuum pump. 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.
    18. CAUTION: DO NOT disassemble water separator.
  18. Remove water separator and inspect for cracks or blockage. See Figure. With water separator port "A" plugged, blow air into port "B". See Figure. 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.
  19. Remove EVAP canister with EVAP-CVCV attached. Attempt to drain water from EVAP canister. If water does not drain from EVAP canister, go to step  21. If water drains from EVAP canister, 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), go to step  21.
  20. Inspect EVAP canister for damage. Replace, if necessary. Also check hose between water separator and EVAP canister for blockage or leak. If problem is found, repair as necessary. If problem is not found, go to next step.
  21. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
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