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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Martin Hand

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.


  • 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 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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