04DTS here with 38k. Never abused. Get in it the other day, and its shifting like it has a B&M shift kit in it! All four gears were slamming in, even when slowly accellerating. I turned around, went home, shut it off. started back up, checked trans fluid=running in park=normal. Took it back out, and back to normal[sm=wtf.gif] I dont get it?
No Check Engine
Checked history codes and found: P0731 and B0429
Anyone else seen this? Am I in for a unpleasant surprise?

 

I had this happen to me but my problem was extremely low transmission fluid. I added some and it shifted like new.

 

B0429 - Temperature Control #3 Rear Circuit Range/Performance, rear air mix door is not exactly at the point that it is commanded; probably not transmission related.

P0731 = First gear incorrect ratio, sensor may be failing
Diagnostic Aids for P0731
Inquire about overloading the vehicle, exceeding the trailer-towing limit, or towing in Overdrive.
Inspect for intermittent automatic transmission input (shaft) speed sensor circuit conditions.
Inspect for intermittent vehicle speed sensor circuit conditions.
Inspect for an incorrect calibration.





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Well after my other reply i discovered my 04 DTS has a transmission leak. So we are in the same boat.

How much is it to get repaired if its a seal? If I need a new one? Do I have to go to a dealer?

 

How many miles on car and did you buy it new? Transmission repairs can be expensive no matter where you take it.

 

There are only 72k miles on the car. I bought it used this past June. Looks like the leak is in the back side of the motor from looking at the drip.

 

when you transmission has a failure in a sensor, the transmission goes into default mode which increases tranny fluid pressure. This is why your feeling the harsh shifts.