Tranny works properly at startup but once the tranny warms up it takes on a mind of it's own. The shift points change. I now have to take the RPMs over 4000 to get it to shift into a higher gear and if RPMs fall below 2300 then it shifts into a lower gear. Basically in-town driving is done at 3700 RPMs which can't be good on the engine.

On the highway (cold) all of the shift points are working and it will shift into 5th gear with no problem. Once it warms up it will drop from 5th into 4th at 65 mph+. I've tried to use the manual (steptronic) and it won't shift into a higher gear. It will show it going into higher on the display but once I release the lever, the display will show the current gear. I can still downshift with steptronic but not upshift.

This problem came on over the weekend. I took it into dealership and they found one code in the tranny which showed 'high temp reading' basically. They tested the tranny temp and it tested around 90 but the sensor was saying 140 - both in celcius I believe.

It happens 100% of the time once the tranny warms up. It is not intermittent.

I've read through a few other tranny threads and I'm thinking that it's the wiring harness with temp sensor that needs to be replaced but wanted to see if there were other parts that need to be replaced while I'm in there. Pulse Generators? Servos? Etc. Vehicle has 91k miles and has never had tranny fluid or any other service performed on the tranny.

Thanks