Subaru AT Oil Temp Lite Diagnostic Procedure

Early model Subaru Automatic transmission diagnostic code retrieval procedure. This procedure is specifically for 98 Subaru OB but stays the same for all similar models. I do not believe this will work for the 2.5 SOHC Subaru Outbacks. Locate the diagnostic connector under the dash then follow the procedure. TCM will flash codes through the “AT Oil Temp” lite. Please post any questions to comments below, thank you.



This post was written by: Martin Hand


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About Martin Hand

ASE Certified L1 Advanced Mastertech. Martin Hand has over 15 years experience in Asian and European Import Auto Repair. Specializing in electrical diagnosis, engine performance, AT/MT transmission repair/rebuild. Martin is also pursuing a degree in Computers Science & Information Systems starting at Portland Community College while he plans to transfer to OIT. Certified in Java application level programming, experienced with other languages such as PHP, Ruby, JavaScript and Swift. Martin has future plans of automotive diagnostic software development.


  • Chad Thomas Engebretson says:

    Help!!! Had a severed wire in trans when pan pulled. Blue wire going solenoid in bottom when pan was pulled. Reconnected the wire connector broke but have rechecked since and is fine, was reading the torque convertor solenoid voltage code, went away when vehicle started. Have EGR code now but trans only drives in 1st and 2nd gear. If it shifts to 3rd which is rare, slips all the way. When lifting car letting it engage 1st or second gear when hitting brakes (all new hardware) torque convertor. Sounds like a bunch of bolts rattling around or a heat shield loose type of sound. Where do I start? Pulling trans now, but need fixed now and have very little money. 96 outback 2.5 4eat. Also gear shifter does not line up with gear selected. Reverse is N, drive is 3 no real click between 1 and 2 on shift lever.

    • Martin Hand says:

      Sounds like more than one problem. First off make sure there is not a blown fuse from the wires in the pan. Also consider there is EGR failure and transmission failure at the same time. The shift indicator is adjustable it’s either out of adjustment at the shift console or the sensor on the transmission is also adjustable.

  • Ady says:

    Hi, i have subaru impreza sti 2.5 2010.

    i have an issue where this AT temps flash out with ABS and traction. Recently i have replace the AT fluid and when they diagnosis nothing error shows up..after 3 days,this things happen again.. do you have any idea what cause the problem?

  • tosh says:


    I have a 2010 Legacy GT
    this morning the AT OIL temp start blinking again.
    last week when it blink Subaru dealer told me to replace the ATF oil, so i did.
    when i drove it this morning high temp started to blink again.
    what should i do is this a sensor related or computer related issue.

    • Martin Hand says:

      Changing the transmission oil will not fix your AT Oil Temp lite. The lite comes on when there are diagnostic trouble codes set. Need to read the codes and start your diagnosis from there.

      • tosh says:

        thank you for quick reply.
        i will bring it to the dealer.
        i notice that when i install the LED break light problem started.
        so yesterday i replace it to the normal bulb.
        as of today drove it for more that 60km AT oil temp and other ABS and traction control error is gone.
        does it have to do anything with the LED bulb?

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