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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 >> P0102: Mass Air Flow Circuit. Low Input. >> Fault Isolation Procedure
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Fault Isolation Procedure

  1. Checking air leakage: Check that there are no major leaks between the mass air flow sensor and the throttle. If the system is airtight, go to next step, otherwise go to step  9.
    NOTE: The air leak must correspond to a 20 mm hole for a DTC to be generated.
  2. Checking the sensor's power supply:
    • Turn the ignition switch to the ON position.
    • Unplug the connector: Mass Air Flow Sensor (205).
    • Connect Test Lamp (86 1 857) to pin 3 of the female connector and a good grounding point.
    • 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 test lamp illuminates, go to step  4, otherwise continue with next step.
  3. Rectifying the lead: The lead from crimp connection J24 to pin 3 of the female connector is faulty. Rectify and go to step  9.
  4. Checking the sensor's grounding:
    • Connect Test Lamp (86 1 857) to pins 3 and 2 of the female connector.
    • 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 test lamp illuminates, go to step  6, otherwise continue with next step.
  5. Rectifying the lead: The lead from crimp connection J15 to pin 2 of the female connector is faulty. Rectify and go to step  9.
  6. Checking the control module's sensor input:
    • Take a voltage reading: (1,2) Mass air flow sensor (205:1 & 205:2).
    • 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 reading shows 4.9-5.1 volts, go to step  8, otherwise go to next step.
  7. Rectifying the lead: The lead from pin 1 of the female connector to pin 65 of the control module is faulty. Rectify and go to step  9.
  8. Changing components: Change the mass air flow sensor. When finished, go to next step.
  9. Checking mass air flow when under partial load:
    • Turn the ignition switch to the ON position.
    • Contact ECM.
    • Read value: Airmass Deviation from Calculated (ECM).
    • Drive the car with a steady high engine load. Driving uphill is recommended.
    • Observe the diagnostic tool.
    If the tool shows -15% to 15%, the steps taken to rectify the fault were correct. Clear DTCs from all systems. If the reading is incorrect, the air mass variation indicates that there is still a leak. Refit the old mass air flow sensor if it has been changed and continue to look for an air leak between the mass air flow sensor and the throttle body.
Fig 1: Mass Air Flow Circuit
G00207341Courtesy of SAAB-SCANIA OF AMERICA, INC.
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