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AT OIL TEMP light on after trans swap

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Posted (edited)



I have a 2007 Legacy GT automatic with 254,000 miles on it. The engine has under 100k and it has a used transmission that was just rebuilt with about 120k on it.


The only issue with the car is that the AT OIL TEMP light comes on (flashing) and stays on until the car is restarted. It comes on religiously after about 15-30 seconds in any gear other than park or neutral. Pretty sure it’s a sensor issue. I haven’t successfully been able to read a temp from a scan tool yet to see what the sensor is reading, if anything. The transmission fluid is brand new, and the dipstick reads that it’s at the correct level. Nothing is leaking from the car. I verified that the transmission is circulating coolant, and the car’s coolant temperature never exceeded 195 on my drive.


I’ve read that there is a possibility that if the trans oil pan gets dented or warped at all, there is a good chance that sensor will break. I’m pretty sure the TCM is fine since this never happened last week with the old trans. I checked connections to the tcm and transmission and all seemed good. I’ll reconnect and clean them tonight and see if that makes a difference.


Thanks for any insight!

Edited by hpellerin
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I would try to send PM to member ClimberD, You can see his post about 5 post down from this one.


You may also want to put a post in the 4th Gen forum linking to this one.


The service manual may help you,



305,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.


Engine Build - Click Here

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Sounds like the replacement trans has a bad temp sensor in the valve body. I would start with replacing that sensor. If you have your old Trans you could start by taking the pan off of it and locating the sensor. Then swap it into the new/used trans in the car.
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