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Home >> Subaru >> 2003 >> Outback Base, 4D Wagon, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.5L >> Diagnostic Tests >> DTC P0068: Intake Manifold/Barometric Pressure Sensor Circuit, Range Performance Problem >> Diagnostic Procedure
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Diagnostic Procedure

  1. Perform basic diagnostic procedure. See BASIC DIAGNOSTIC PROCEDURE . If DTC P0068 is only DTC set, go to next step. If any other DTCs exist, diagnose and repair those DTCs. Do not diagnose DTC P0068.
  2. Inspect air intake system hoses for holes, cracks or loose bolts and connections. If any problems are found with air intake system, repair as necessary. If no problems are found with air intake system, go to next step.
  3. Start engine and bring to operating temperature. Turn ignition off. Turn ignition on. Ensure A/C and all accessories are turned off. Using scan tool, monitor intake manifold pressure sensor signal. Reading should be 21.65-31.50 in. HG. Start engine and let idle. Using scan tool, monitor intake manifold pressure sensor signal. Reading should be 5.91-13.78 in. HG. If readings are as specified, go to next step. If readings are not as specified, replace intake manifold pressure sensor.
  4. Turn ignition off. Turn ignition on. Using scan tool, monitor the throttle position (TP) sensor while throttle is fully closed. If reading is less than 5 percent, go to next step. If reading is greater than 5 percent, adjust TP sensor. See ON-VEHICLE ADJUSTMENTS .
  5. Using scan tool, monitor the TP sensor reading while throttle is fully open. If reading is greater than 85 percent, replace then intake manifold pressure sensor. If reading is less than 85 percent, replace the TP sensor.
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