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Home >> Saab >> 2001 >> 9-5 Base, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Fault Code Diagnosis >> P1451: EVAP Tank Pressure Sensor - Performance Problem >> Fault Isolation Procedure

Fault Isolation Procedure

  1. Checking the sensor's power supply:
    • Turn the ignition switch to the ON position.
    • Unplug the connector: Pressure sensor, EVAP (585).
    • Take a voltage reading: 585:1 and B-.
    If the diagnostic tool shows 4.9-5.1 volts, go to step  3, otherwise go to next step.
  2. Rectifying the lead: The lead from crimped connection J21 to pin 1 of the female connector is faulty. Rectify the fault and go to step  9.
  3. Checking the sensor's grounding:
    • Take a voltage reading: 585:1 and 585:2.
    • Jiggle the leads and in-line connectors at several places and in different directions to reveal intermittent breaks and short circuits in the wiring harness. Observe the multimeter, test lamp or diagnostic tool while doing this.
    If the diagnostic tool shows 4.9-5.1 volts, go to step  5, otherwise go to next step.
  4. Rectifying the lead: The lead from crimped connection J22 to pin 2 of the female connector is faulty. Rectify the fault and go to step  9.
  5. Checking the control module's sensor input:
    • Contact ECM.
    • Read value: Fuel Tank Pressure.
    If the diagnostic tool shows 2.5 kPa, go to next step, otherwise go to step  7.
  6. Checking the control module's sensor input (continued):
    • Connect a jumper lead between pins 2 and 3 of the female connector.
    • Read value: Fuel Tank Pressure.
    If the diagnostic tool shows -2.5 kPa, go to step  8, otherwise go to next step.
  7. Rectifying the lead: The lead from pin 3 of the female connector to pin 59 of the control module is faulty. Rectify the fault and go to step  9.
  8. Changing components: Change Pressure sensor, EVAP. When finished, go to step  9.
  9. Initiating diagnostics:
    • Check the diagnostic status of the trouble code with the diagnostic tool.
      NOTE: Do not touch the brake pedal.
    • Start the engine and run it at idling speed.
    • Let the engine run at idling speed until the coolant temperature exceeds 60°C and for at least 4 minutes.
    • State what the diagnostic tool shows:
      • OK - The steps taken to rectify the fault were correct. Clear the DTCs in all systems.
      • NOT READY - The diagnosis has not yet been performed or has been cancelled. If the diagnosis has been cancelled, it can be restarted if the car is rolled a few meters and then stopped with the handbrake.
      • DTC - Diagnosis indicates that the fault is still present.
Fig 1: EVAP Tank Pressure Sensor Circuit (4-Cyl)
G00207363Courtesy of SAAB-SCANIA OF AMERICA, INC.
Fig 2: EVAP Tank Pressure Sensor Circuit (V6)
G00207419Courtesy of SAAB-SCANIA OF AMERICA, INC.
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