Trans experts opinions needed- kind of a long story.. sorry in advance

[mike_dmt]

So, I have an 01 X, with the 4.4. 140,000 miles. Overall, this thing is in excellent shape, but the tranny is driving me nuts.

It's been acting up for quite a while. I had the stealership do a software update a while back, but it was still a bit wonky.

I did a fluid and filter change about 5k ago, and it didn't really change much.

What its doing is this: Hot or cold, I can be driving along at 30-35 mph, and it will just downshift into second and stay there,. It wont shift up, even if I try and shift it with the tiptronic.

So, back to the stealership today. They said it was a quart low of fluid, which I kind of doubt, since I checked it 1000 miles ago, and it was full. But OK.

Then they tell me, "t shows gear monitoring faults, indicating slippage, and a fault code for the trans oil temp sensor" (the internal one). Can the two be related?

I've heard of similar symptoms with trannies downshifting trying to get cooler fluid into the trans, but mine will do it cold, or hot, doesn't matter.


My question is, Should I bother doing the internal temp sensor and harness and new fluid? Or with the "slippage" is the trans done?