Always a first time, had the transmission warning light come on and car went into limp home mode, luckily I was nearby. Any thoughts on this. Auto trans Fluid changed at 64K miles now done 90K so not thinking it is the fluid.

Hopefully some insights would be great. Just about to put OBD reader on also.  

Morning Paul

Check the level is correct and try a tube of Dr Tranny I had a similar issue with my E53 4.6is Diagnostic on mine first said Turbine (Torque converter) then valve body I changed the fluid and added Dr Tranny no re-occurrence since. Issue started at 110k (Fluid change had been done at 84k) now on 164k much cheaper than the alternative. 

Your problem could be a tiny bit of debris in the valve body or just something sticking. I flushed mine by disconnecting the trans hose at the transmission cooler on the Rad attach a piece of clear hose and feed it into a marked clear container (I used an old Coke bottle marked at 1ltr points), then with the help of my son in the car start the engine until 3 ltrs are in the Coke bottle. Engine off refill the trans with 3 litres of new Fluid and repeat, I pushed 10ltrs through which ensured the torque converter was clean as well. A normal fluid change will leave the torque converter full of old fluid and whatever is floating in it. Run the engine until the trans is up to temperature check the levels and put in a tube of Dr Tranny job done. Just about to do my E70

Dave

Greydog, is there anything on BMWs you have'nt experienced. Really great advice on the flushing through and restock of trans fluid. Also the use of the additive Dr Tranny. Got good experience on use of additives as I used the liqui moly additive to help with the valve stem oil seal issue I had. Great success.

Will advise on what I find.

Paul  

Ha Ha, I dare say loads and loads of stuff that I have never seen or even heard of but as they say every day is a school day

Owned BMW's since 2004 plus there are 7 in the immediate family without their friends and being an inquisitive Engineer I just have to know "how and why" an ex-neighbour worked for BMW UK even he asked for help a couple of times 😅 Now with my E70 I am learning about BMW Diesel's a whole new world of opportunity and as my wife says it keeps me out of the pub

I have always been the same with any car I have owned and there have been a lot since the early 1960's

Good Luck with the scan and flush

Dave