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Home >> Nissan-Datsun >> 1998 >> 240SX Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Testing - 2.4 >> Diagnostic Tests >> DTC P0450: EVAP Control System Pressure Sensor >> Procedure
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DTC P0450: EVAP Control System Pressure Sensor: Procedure

  1. Check rubber hose to EVAP control system pressure sensor for damage or clogging. See Figure. Repair as necessary. Loosen and retighten 2 ground wires located on intake manifold near fuel injectors. See Figure. Disconnect EVAP control system pressure sensor harness connector. Turn ignition on. Using DVOM, measure voltage between EVAP control system pressure sensor harness connector terminal No. 3 (Light Green/Red wire) and ground. If voltage is approximately 5 volts, go to next step. If voltage is not approximately 5 volts, check and repair for open or short in Light Green/Red wire between PCM and EVAP control system pressure sensor harness connectors.
  2. Turn ignition off. Using DVOM, measure continuity between EVAP control system pressure sensor harness connector terminal No. 1 (Black wire) and ground. If continuity exists, go to next step. If continuity does not exist, repair open in Black wire between PCM and EVAP control system pressure sensor harness connectors.
  3. Leave ignition off. Disconnect PCM harness connector. See Figure. Using DVOM, measure continuity between EVAP control system pressure sensor harness connector terminal No. 2 (Green wire) and PCM connector terminal No. 67. See Figure. If continuity exists, go to next step. If no continuity exists, repair open or short in Green wire between PCM and EVAP control system pressure sensor harness connectors.
  4. Check EVAP canister purge volume control valve and EVAP canister vent control valve. See DTC P0443 OR P1444:  EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE and DTC P0446, P1446 OR P1448:  EVAP CANISTER VENT CONTROL VALVE. Repair or replace as necessary. If components are okay, go to next step.
  5. Disconnect EVAP control system pressure sensor connector. Reconnect harness connectors. Connect vacuum pump to vacuum port. Turn ignition on. Measure voltage between ground and PCM harness connector terminal No. 2 (Green wire) by backprobing connector. Without vacuum applied, voltage should be 3.0-3.6 volts. Apply 2.8 in. Hg (70 mm Hg) to sensor. With vacuum applied, voltage should be about 0.4-0.6 volt. If voltage is not as specified, replace EVAP control system pressure sensor. If voltage is as specified, go to next step.
  6. Check EVAP purge line for cracks. Inspect EVAP system components for damage or poor connections. Remove EVAP canister with EVAP canister vent control valve attached. See Figure. Turn EVAP canister over and check for water leaking from EVAP canister vent control valve. If water is not leaking from valve, go to next step. If water is leaking from valve, weigh EVAP canister with valve attached. If canister is less than 4.0 lbs. (1.8 kg), go to next step. If canister is equal to or more than 4.0 lbs. (1.8 kg), replace EVAP canister and retest system.
  7. Disconnect and reconnect harness connectors in circuit. Check PCM connector for damage or corrosion. Repair as necessary.
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