Hello All,
I have a 2009 BMW 550i which its automatic transmission is faulty and would want to replace it but having a challenge of having the right transmission model. The original Transmission model for the car is ZF 6HP28 automatic transmission, couldn't get it so I mounted ZF 6HP26 automatic transmission but car would start, sometimes shift to neutral on its own but wont drive. My E60 550i is V8 and uses N62 engine while the 6HP26 automatic transmission was pulled out from same year 7series E65 V8 using same N62 engine( both engines looks exactly alike in their exteriors). I would want to ask if EGS ISN edit or reflash/coding can adapt the 6HP26 to my car and make it work properly? I already know its a function AUTOHEX II can do but just want to be sure it will work in this my case. I appreciate any advice or suggestions that would be helpful in getting my car back on the road, thanks to you all
Best Regards,

For 2009 E60 doesn't have EWS security on transmission,so if used unit compatible with car just connect and code is enough.In your case go to indiv programming and check the status for EGS,if not compatible you can try to flash in expert mode.Also check with wiring if shifts to neutral by its own.

The problem is that because the transmission comes from a 7 series, the EWS security has been activated already. The EGS EWS has to be activated in CAS and the transmission synced.

Try flashing with expert mode. The shifter is integrated in szl in e65 so most likely thats why you cannot shift.

Actually, there appears to be some slight physical differences in the internals of the two gearboxes; 6HP28 mechatronic has 9 solenoid valves of which none is black while the 6HP26 has 9 solenoid valves also of which one is black. When I swap in my original 6HP28 mechatronic into the 6HP26 transmission, the car would start and drive but would still fail on TRANSMISSION MALFUNCTION FAULT( I observed this failure to be clearly because the mechatronic of 6HP28 oil groove/ flow path is not inline properly with that of 6HP26 turbine, that is flow patterns are different so one won't match the other). The 6HP26 gearbox has same mounting as the 6HP28 and is seating well on the car. Though I observed BMW uses the 6HP28 gearbox only on 550i and 6series while V8 7series and X5( all naturally aspirated) uses the 6HP26 gearbox though they all share same N62 engine. My question is has anybody succeeded in adapting(by coding/programming) a different transmission model( like 6HP26 for 6HP28) on any BMW? Just asking as I have already returned the 6HP26 gearbox to the seller and requesting it again means outright purchase if it works or not. Anyway, I am ready to give a shot at it in case anyone has tried it and succeeded.