Hi, I have a problem with my auto box on my 2008 x3, when driving, not necessarily fast or hard, as it changes from 5th to 6th gear it just looses all power and drops into neutral?

I then have to stop the car, turn off the engine, restart and all seems to be OK again until the next time (maybe minutes or days ) If I run the car in 'manual' and keep it in 5th it seems better.

I have changed the oil in the transmission, I am leaning towards solenoid problems, unfortunatly my gearbox is a ZF6HP 21X, and everything seems to be dearer for this gearbox.

Is there any way to tell which solenoid may be the problem as the fault only seems to be one gear? all the other gears work fine and there is no problems in first / reverse as other forums mention.

Has anyone else had this problem, any ideas would be well received.

Morning John

When I brought my first X5 it suffered from the dreaded lurch (a hard change into 1st when slowing or stopping) the BMW dealer (and I have discovered from other forums they are not alone) at that time was saying "new Gearbox" as they can't be serviced they are sealed for life!!

I contacted ZF UK in Crick who first asked what mileage and recommended a service and software update, they gave me the name of a ZF agent near Dorking not far from me who carried out the work. The Agent told me the box should be serviced every 60 to 80000 kilometers, seems "sealed for life for BMW means the end of the Warranty. It rang faultlessly afterwards, current X5 had it's first ZF service at 75k and is now booked in for it's second service 146k  I know I could get it done cheaper or even do it myself but I guess I am paying for peace of mind.

My advice would be Google ZF services UK and find your closest centre they will have all the right kit to plug in and test all components in the box, cycle all the solenoids in the motronic unit  and give a comprehensive analysis plus update all the software.

Fingers crossed it is a simple fix and not wallet busting 

Dave