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Mike V.
Mike V., Subaru Technician
Category: Subaru
Satisfied Customers: 25201
Experience:  Certified Subaru Technician, factory trained by Subaru.
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AT Oil temp light flashes 16 times after start up, what does this

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AT Oil temp light flashes 16 times after start up, what does this indicate and where do I find the problem?
HI there! The number of flashes doesn't really indicate the code. What it does indicate is an electrical problem with the transmission. You need to have the transmission control module scanned for codes to see what the failure is. This could be a problem with any of the solinoids inside the transmission, one of the speed sensors or possibly even the trans temp sensor. There just is not way to tell without the code. Best bet is to have the TCM checked for codes, then determine if the repair is something you can do yourself to save some money. Hope this helps!
Customer: replied 7 years ago.
hey Carguy1,
First, is the transmission control module part of, or separate from, the OBD II ? Found two trouble codes(OBD II) for the transmission range sensor and fluid temp. sensor or circuit malfunction in Haynes manual. Will a standard code reader suffice to read the trans module?
Could a loose connection cause the fault and if the trans module is different from the OBD II, where is it and trans temp sensor located?
What's up w/ the dipstick being so hard to read...fluid seems to be collecting on the stick during withdrawal which makes it hard to determine the correct level and would low fluid levels cause the light flashes? Light stops after initial start up.
Really appreciate you taking the time for all these questions
OK, are you getting codes for the range sensor and the temp sensor with the code reader?
Customer: replied 7 years ago.
NO, have yet to read codes. Thought it would help to know where they were located to check connections.
Well, you actually access the trans module through the same connector as the OBDII, but I don't think you will be able to access the trans module with just a code reader.
It is possible this could be a bad connection. If you look at the back of the engine you can see two swuare black plugs, might not hurt to unplug and replug them in. Bad connections can cause problems always. Also check the ground wire back there. It runs from the firewall, down to the trans mount bracket.
As for the dipstick, yes, they are a pain in the you know what. Check it without the car running and make sure there is fluid on it. If it is low cold, ass a quart.
Let me know if you need more! I will see what I can do!
Customer: replied 7 years ago.
"ass a quart" was appropriate..rechecked fluid and it appears it may be overfilled (the best I can tell on the stick as fluid is past the hot full mark but majority under the lo cold mark??? Will be starting over by draining some of the fluid and add it back slowly to make sure. Wires and ground appear tight so what will a diagnostic cost?
oooppss! Wrong keys!!
didn't mean ass:)
anyway, probably one hour diag time at the dealer. This is what most charge to put it on the scanner and read the codes, plus a little diag time.
Since it doesn't seem to be affecting the transmission right now I suspect the atf temp sensor might be the problem.
Customer: replied 7 years ago.
Indications point to your diagnosis so on to the next.....where do I locate this sensor and can it be tested w/ohm meter?
It is inside the transmission, it can be tested with an ohm meter, let me see if I can come up with the procedure for you
OK, here we go. On one of the square connectors at the back of the engine, you should find a white wire and an orange wiire. You need to back probe these wires with the ohm meter, then start the car and watch to make sure there is change in resistance.
It will be the square connector with the harness going down the driver side of the car into the transmission. Doesn't say what the resistance will be, just that there has to be change as the transmission gets hot
Customer: replied 7 years ago.
Rats....was hoping it was easy to access...waiting for ohm procedure....if not replaced, will it affect driveabilty ?
Did you recieve my last post? it has the procedure on it

Customer: replied 7 years ago. procedure and again, will not replacing sensor affect driveablity and/ or cause future problems?
If that is the problem, it can affect the drivability down the road. The car needs to know wht the temp is to run properly. To be honest however, I can't be 100% positive what the effects will be.
Customer: replied 7 years ago.
Can one get to the sensor by removing the pan?
Yes, you can drop the pan and it will be located there. You don't even have to remove the filter.
Customer: replied 7 years ago.
OK will proceed w/tests. I assume the sensor would be available through a Subaru Dealer, do you happen to know anywhere else I could get the sensor?
If I need further assistance w/this problem, will my payment cover it?
Thank you for your patience.
I don't know of anyplace other then the dealer to get this part, because it is so specific. If you have more questions about this issue it should be covered.
Mike V. and 4 other Subaru Specialists are ready to help you
Customer: replied 7 years ago.
Carguy1, accessed the OBDII with "Snap-On" code reader, no codes displayed, changed trans fluid (took 4 3/4 qts.), light still flashes. Oil temp sensor seems to be part of sensor assembly and would rather not replace anything but temp sensor ($200+ for sensor assembly)...can I replace just the oil temp sensor without replacing all and , if so, any idea on part number? Is there another test port for the TCM or is there a setting on code reader to access the TCM through the OBDII? Suggestions? Thanks
Let me ask you this, are the flashes of different lenghts? Long and short to come up with the 16 flashes?
Customer: replied 7 years ago.
Light flashes once on start-up, then 16 flashes seems to be of same length, short
OK, I would like to take a step back here. Pull fuse #14 from inside the car for 30 seconds. Then put it back in and see if the light stops flashing. Then if it does, start flashing let me know. It should be spitting out a code,there just is no 16. We are actually looking for a 27 for the temp sensor. 2 long and 7 short flashes.
Also, for the scanner. I am not 100% sure,but you should be able to go into the menu on the scanner and toggle it to tcm, then read the tcm codes
Customer: replied 7 years ago.
Ignition on or off?
You pull the fuse and leave the key off. After the fuse is out for 30 seconds or more, reinstall it then turn the key on and se if there is any change in the light.
If you mean with the scanner, should be with the key on.
Customer: replied 7 years ago.
fuse procedure worked! Light goes off after start-up with no following flashes. What exactly does that do (removing/replacing fuse). Would be nice to have explanation for others if problem is encountered elsewhere....THANKS
That erases old stored codes. It is the backup power line for the transmission control module. Now, I am not saying this is the majic fix, however I will be interested in knowing if the light starts to flash again. I also belive it should flash the code, but the 16 is nowhere in the service manual. This may only be a temp fix. But I wanted to go back to step one.
Customer: replied 7 years ago.
Thanks again...will be sure and contact you if problem recurs.
You are very welcome! Have a great holiday!
Customer: replied 7 years ago.
Best wishes to you and yours for the holidays and the new year.....Do I owe you some more?
not required! It is totally up to you.