2001 e46 325 transmission oil cooling hose break to limp mode

I need a little advise on this. I was on the highway and my car started smoking last week. once towed home I noticed the OIL COOLING PIPE INLET at the ribber end was split in half and the serpentine belt was shredded and wrapped around the fan bolt.

So i replaced the Oil cooling pipe and also bought a new filter and fluid and replaced the ATF fluid from under the car ZF tranny. after changing everything nothing changed the car is still in limp mode and stuck in one of the high gears and will not shift.

I took it to a local tranny guy who a friend takes his 318 to and he gave me these codes.
#143 tank leak detected (major leak)
#8 mass air sensor signal. " I believe this was my fault because after cleaning the
engine of all the fluid when changing the belt, I forgot to tighten the MAS."
#11 thermal oil level sensor.

I'm not quite sure how any of these would effect the transmission and why it will not come out limp mode, Also the mech said he could not figure out anything with the transmission until I get the other codes fixed. Any suggestions could help, thanks.

Safe mode/limp mode probably has nothing to do with your possible transmission fluid issue. Safe mode is usually an electrical issue!

Safe mode is initiated when the ECU is sent a signal that detects something unsafe. Like a stuck throttle plate or what it thinks is a stuck throttle due to a bad Mass Air Flow (MAF) or a wet MAF due to someone cleaning their engine and contaminating their MAF sensor. An overheated transmission sensor reading could do it too, and possibly a severly under serviced tranny/low on fluid, but you are associating one with the other for illogical reasons at this point.

1) Do you know how to service a BMW automatic transmission in order to get the correct amount of fluid back in it?

2) If so, you never mention anything else you did to resolve your original limp mode (clean and or tested MAF, cleaned throttle body and ICV / inspect electrical system of each)

3) Why did your serpentine belt frag in the first place? oil soaked from the leaky oil pipe? this is usually due to bad tensioner, water pump or other pulley

I did check a lot of DIY on how to replace the Transmission fluid and the filter, I believe I did it correct and asked a indy after taking it to them if the procedure I did was correct.

The car just hit 114,000 miles and I don't think the tranny was ever serviced because of the black fluid that was in it after dropping the pan.

The only things I did was clean the MAS with MAS cleaner and put it back in after it dried. I assumed it was in limp mode due to not having any fluid in it but that's why i'm here because I'm not sure what to do. I did not (cleaned throttle body and ICV / inspect electrical system of each) Also how would you inspect the electrical system of each?

I didn't see any leaks and normally would in my drive way and I tend to look for that from time to time so I'm not sure why the belt broke. I did have a water leak from the thermostat a while ago and replaced that but I don't know it that would cause the belt to break.

I took it to a indy and they told me that the TCM needs to be replaced but do not know why and are telling me that i have to purchase a new one and get it coded which is about $1200. Can you put a used one in with the same part # or are they correct in saying I have to get a new one and no used ones can be recoded? They also said they weren't sure if the would even fix the issue.

If you have any suggestions I would be more then happy to give them a try over paying $1200 for something that may or may not fix the issue.

Thanks again.

Update a used tcm can be used and reprogrammed. I had one and had it replaced and it took the car out of limp mode for a month or so. Then right back into limp mode but with different issues this time. So just to answer my original question yes you can reprogram and TCM from a different car and even rebuild the one you have. I had an indy do it. New issues will it slips 2-5 gear and after about little while of driving it goes into limp mode. If I turn the car on and off it takes it right out of limp mode then goes back in it after driving again. So not sure what I'm going to do this time but I think i'm about to give up. sounds like tranny replacement or get rid of her. boo