840Ci error code 39 - Servomotor choke valve

Hi
Long time reader 1st time poster.
I've just purchased a 840ci the traction control light is permanently on. I’ve had the car code read and is coming back as error code 39, servomotor, choke valve any way of testing this part or repairing it. I've taken the unit off it seems to be working fine has any one else had this problem or any one point me in the right direction.
Dave

Hi Dave,

My name is Cesar, I have a 96 740IL and I'm having the same problem with this car, code 39 with the traction control light on. Did you solved your problem already? Please advice
Thanks,

i have 528i with code 39 chock valve and asc light stays on? any help please