04 Legacy with auto box problem, help needed please

Gears slip once warmed up and then loose all drive, stop for 10 mins and I get a bit of drive but just for 500 yards

i have changed box oil and filter and oil was black and had some fillings in it but still slipping and loosing drive! 

Is it a fix? Does anyone have a replacement box TV1B7MFAAB

thanks 

Wotcha and welcome - sorry to hear this - does sound like a rebuild / replace is necessary - how many miles on the clock + which transmission oil did you use?

90k on clock and used shell Spirax S4ATF HDX as per shell site 

you know anyone who would have a replacement box? Cheers

Did it do it before the fluid change?

To check the level of the fluid I think you have to do something like put the lever on all modes and check it with the lever in a certain position?

 

There is a diagnostic for the transmission, it works on my 2001 legacy.

Look up 'secret handshake', follow the steps then the transmission computer will flash the codes to you on the dash.

 

 

 

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It did it before the oil change and I checked levels following the Subaru way, fill it, move thru all gears, fill it again and check while engine is running 

where and what is the 'secret handshake' is that not what the masons do 😂