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Home >> Infiniti >> 2003 >> G35 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0451: EVAP Control System Pressure Sensor Performance >> Diagnostic Procedure

Diagnostic Procedure

CAUTION: DO NOT use ECM ground terminals when measuring voltage. Damage to ECM transistor may result. Use engine ground.

For component location, see COMPONENT LOCATIONS  . For connector terminal identification, see CONNECTOR IDENTIFICATION  .

  1. Disconnect EVAP control system pressure sensor harness connector B202. Check sensor harness connector for water. Water should not exist. If water does not exist, go to next step. If water exists, repair or replace harness connector.
    2. CAUTION: Always calibrate the vacuum pump prior to using it. DO NOT apply less than -27.56 in. Hg (-93.3 kPa) or more than 29.91 in. Hg (101.3 kPa) of vacuum to EVAP control system pressure sensor.
  2. Remove EVAP control system pressure sensor with harness connector connected. Remove hose from EVAP control system pressure sensor. Install a vacuum pump to EVAP control system pressure sensor. Turn ignition on. Use pump to apply vacuum and pressure to EVAP control system pressure sensor. Measure voltage between engine ground and ECM terminal No. 60 by backprobing. Voltage should be 1.8-4.8 volts with no vacuum applied. Using a hand vacuum pump, apply -7.87 in. Hg (-26.65 kPa) of vacuum to pressure sensor. Voltage should be 2.1-2.5 volts less than voltage measured with no vacuum applied. Voltage should decrease as vacuum is applied. If voltage is as specified, go to next step. If voltage is not as specified, replace EVAP control system pressure sensor.
  3. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
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