transmission - a mind of its own!!

[hawkeye12345]

After reading this it may have saved me from shooting my X5. Here is my issue as best as I can describe it.

Driving down the Interstate today at 70 mph. The tranny just shifted into 4th for no reason. No accel or decel, just driving along. It wouldn't shift back into 5th. After exiting Interstate, it had hard shifts down to 3rd, 2nd and 1st. At accel from light, 1st to 2nd was fairly smooth but getting to 3rd took to over 4k RPM - same for 4th. I think normal shift point is around 2500.

Took it to indy shop where they found a code that showed tranny temp at 136 C but actual temp as tested was 89 C. They weren't sure what the issue was so I drove home. Same tranny issues as above on the drive home.

If I replace the tranny temp sensor, will this theoretically fix the problem? Have never had any trouble with the tranny prior and have no reason to believe it's going to go kablamo.