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Home >> Nissan-Datsun >> 2000 >> Altima GLE >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0450: EVAP Control System Pressure Sensor (EVAP-CSPS) >> Procedure
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DTC P0450: EVAP Control System Pressure Sensor (EVAP-CSPS): Procedure

  1. Check EVAP-CSPS hose for blockage or leak. See Figure. Repair as necessary and retest system. If hose is okay, loosen and retighten 2 engine ground bolts located on intake manifold, near fuel injectors. Disconnect EVAP-CSPS harness connector. If water exists in connector, repair or replace connector and retest system. If connector is okay, go to next step.
  2. Turn ignition on. Measure voltage between ground and EVAP-CSPS harness connector Red wire. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, repair open or short in Red wire and retest system. See WIRING DIAGRAMS article.
  3. Turn ignition off. Check continuity between ground and EVAP-CSPS harness connector Black wire. Also check circuit for short to voltage. Repair as necessary and retest system. If ground circuit is okay, go to next step.
  4. Disconnect ECM harness connector. See Figure. Check continuity of White wire between EVAP control system pressure sensor harness connector and ECM harness connector terminal No. 67. See Figure. Also check circuit for short to ground and short to voltage. Repair as necessary and retest system. If circuit is okay, go to next step.
  5. 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. EVAP-CPVCV should switch in one second or less. If operation is as specified, go to next step. If operation is not as specified, replace EVAP-CPVCV and retest system.
  6. Remove EVAP-CVCV. Using jumper wires, apply battery voltage and ground 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 one second or less and rust should not exist in port "B". If operation is as specified, go to next step. If operation is not as specified, replace EVAP-CVCV and retest system.
    7. CAUTION: DO NOT apply more than 5.91 in. Hg 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.
  7. Remove EVAP EVAP-CSPS with its harness connector connected. Turn ignition on. Using a suitable hand vacuum pump, apply 2.76 in. Hg of vacuum to EVAP-CSPS. Measure voltage between ground and ECM terminal No. 67 by backprobing. See 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 and retest system.
  8. Remove EVAP canister with EVAP-CVCV attached. See Figure. Attempt to drain water from EVAP canister. If water does not drain from EVAP canister, go to step  11. If water drains from EVAP canister, go to next step.
  9. Weigh EVAP canister with EVAP-CVCV attached. If weight is less than 4.0 lbs. (1.8 kg.), go to step  11. If weight is more than 4.0 lbs. (1.8 kg.), replace EVAP canister and check hose between water separator and EVAP canister for blockage or leak. Repair as necessary and retest system. If hose is okay, go to next step
    10. CAUTION: DO NOT disassemble water separator.
  10. Remove water separator and inspect for cracks or blockage. 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 and retest system.
  11. No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article.
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