Transmission issue 8HP70X
 

2011 X5 50i (150k)
8HP70X

DTC
4EC8 - Position sensor
4EC9 - Parking lock
4E98 - Transmission ratio monitoring, clutches A, B and D

Here are the exact symptoms:
When cold throws 4EC8 (position sensor) car drives forward and backwards and possible engage Park

After couple minutes D and R not engaging shifts in N (N is flashing) unable to shift in to P

Checked tranny fluid and is full but the fluid is really really dark and the filling plug was almost impossible to loose so clearly fluid never changed.

First thing what I'm about to try is to change the fluid and filter but I'm not expecting that it will solve the problem.

Seems like pressure issue. once the fluid warms a little won't shift.

Does anyone know if it's worth to do valvebody rebuild and solenoids?
Really don't want to spend money on rebuilt and solenoid kit just to find out that the internals of the tranny are shot. I rather skip that part and get another trans.

First, I'd check to see if the mechatronic sleeve has been leaking internally or if there is water intrusion in the plug for the EGS. That will cause all kinds of electrical errors to be reported. Leaking could also cause the tranny to be slightly low on fluid...

Then, I'd do a trans service including the tube/bridge seals, fluid, and mechatronic sleeve.

If that didn't work... then I'd proceed to the more expensive stuff if you want to keep the X5. IE: rebuild the valve body. And then lastly replace the trans. I went through all of this with our 6hp26x in our X5.

Thank you for your reply. But what you're referring to are common 6hp issues. Bridge and seals not sealing properly causing pressure loss are very common on 6hp transmissions I was inside few of them but 8HP doesn't have these seals.
My question is if it's even worth the shot to try rebuild valvebody + solenoids as the cost would be nearly same as used transmission. But if I could avoid to pull this big boy out I would definitely prefer that.

Forgive me. Wasn't aware the 8HP had changed design that much. The 8HP in our F15 X5 did not get its valve body dropped so am not as familiar with that as the 6HP, of which I have many (6HP28x, 6HP19, 6HP26x, and 6HP26z). :D

After looking at the parts diagrams, in your case, I'd check the mech sleeve for trans fluid or water intrusion as a starting point.