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Discussion Starter #1
2010 Forester, NA with 4EAT. Drained and filled transmission. After two drive cycles, the CEL, AT temp, Cruise, and ABS lights started flashing. Several TCU codes were listed, including network failure.
Copied the codes, then erased them. Have completed five drive cycles with no new codes of any kind. Trans shifts and performs great.

Any ideas what caused this?
 

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2012 Forester X Auto
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1,379 Posts
@Schema46 -
The trans fill is unlikely to have caused anything, and it's more likely just a coincidence, especially since it is working fine now, and was after you replaced the fluid.
It sounds like the classic "glitch". A transient electrical issue (network failure) causing a host of errors...
How many times has your computer crashed for absolutely no reason and you can't replicate the problem...
Sound familiar?
It's the same thing.. Welcome to the dark side of computers making cars better.
 

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2010 Forester Premium X AT
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998 Posts
My guess is that a piece of crud got into one of the solenoids. Usually the first TCU fault will just throw a temporary code and put the AT into limp. When you restart, it takes it out of AT limp, but leaves the temp code... once the ECU gets the second fault from the TCU when a temp code is already present, it will light up the dash. Sounds like this is what happened to you.

You might want to hook up an OBD reader while you drive it around to see if you're getting any temp codes populating before the dash lights up. This really helps with troubleshooting. They have some pretty cheap bluetooth readers out there now that will just connect to your smartphone.
 

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Discussion Starter #4
Thanks. I have a Bluetooth Torque reader that is always connected. Monitor daily. So far no new codes. Historical codes gone and no pending codes.
 

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Discussion Starter #5
So it did it again, but this time I figured out why. Cheap elm mini OB2 Bluetooth monitor. If you do a trip with the elm on it will light up the dash like a Christmas tree. But there are no codes stored. Has anyone else had this happen with elm mini?
 

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2018 Forester
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113 Posts

I just purchased the Autel one and it shows allot, I want to monitor my CVT temp and this one has it all.
I don't leave it in all the time so I don't drain my battery but this is one if your looking for a good one.
 
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