2008 Subaru Outback Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Line Pressure Test: Measurement

NOTE: If the clutch or brake shows a signs of slipping or shift feel is not correct, check the line pressure.
  • Excessive shock during up-shift or if shifting takes place at a higher point than for normal conditions, this may be due to the line pressure being too high.
  • Slippage or inability to operate the vehicle may, in most cases, be due to insufficient oil pressure for the operation of clutch, brake or control valve.
  1. Line pressure measurement (under no load):
    1. Before measuring line pressure, jack-up all the wheels.
    2. Maintain the ATF temperature at approx. 70 - 80°C (158 - 176°F) during measurement. (ATF will reach the temperature above after idling the engine for approx. 30 minutes with the select lever in "N" or "P".)
  2. Line pressure measurement (under heavy load)
    1. Before measuring line pressure, apply both the foot and parking brakes with all wheels chocked (Same as for "stall" test conditions).
    2. Measure the line pressure when the select lever is in "R" or 2nd of manual mode with engine under stall conditions.
    3. Measure the line pressure within 5 seconds after shifting the select lever to each position. (If the line pressure needs to be measured again, allow the engine to idle and cool it down for more than 1 minute.)
    4. Maintain the ATF temperature at approx. 70 - 80°C (158 - 176°F) during measurement. (ATF will reach the above temperature after idling the engine for approx. 30 minutes with the select lever in "N" or "P".)
  3. Remove the test plug and attach the ST instead.

    ST 498897200 OIL PRESSURE GAUGE ADAPTER

    Fig 1: Identifying Test Plug
    G05668246Courtesy of SUBARU OF AMERICA, INC.
  4. Connect the ST1 with ST2.

    ST1 498897200 OIL PRESSURE GAUGE ADAPTER

    ST2 498575400 OIL PRESSURE GAUGE ASSY

  5. Check for duty ratio changes by adjusting the acceleration pedal position using the Subaru Select Monitor.
    STANDARD LINE PRESSURE CHART

    Standard line pressure
    Range position Line pressure duty ratio (%) Throttle valve angle Line pressure kPa (kg/cm2 , psi)
    Manual mode (2nd) 25 - 35 Full open 1,000 - 1,300 (10.2 - 13.3, 145 - 189)
    R 15 - 25 Full open 1,500 - 1,850 (15.3 - 18.9, 217 - 268)
    D 35 - 43 Full closed 500 - 800 (5.1 - 8.2, 73 - 116)
  6. Remove the ST and install the test plug.

    Tightening torque: 

    13 N.m (1.3 kgf-m, 9.6 ft-lb) 

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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