need help with Transmission error 17125

[ChiTownAudi]

I need help with my 2001 A6 2.7T Quattro 150 K miles.

The problem is I get the 17125 code (see below) after about 20 miles with the car in the D position. The weird part is that if I select the 4 position the error does not return. The car runs fine and there are no strange noises

Took the car to the audi dealer and they could not isolate the source of the problem said maybe the torque converter, quoted me Mega $$ also stated the oil is lifetime and did not need replacement even at 150 K

However I had the oil and filter replaced by my local tansmission shop the oil looked pretty bad however there was no metal chips or the like present

The 00526 and 01435 only appeared once after a engine oil change I do not believe them to be related to the transmission problem however I list them just incase

Address 02 -------------------------------------------------------
Controller: 4B0 927 156 DJ
Component: AG5 01V 2.7l5VT USA 1617
Coding: 00002
Shop #: WSC 00000
1 Fault Found:
17125 - Torque Converter Clutch Circuit Performance or Stuck Off.
P0741 - 35-00 - -

Address 03 -------------------------------------------------------
Controller: 8D0 907 389 E
Component: ABS/ESP allrad D56
Coding: 06397
Shop #: WSC 02325
2 Faults Found:
00526 - Brake Light Switch-F
27-10 - Implausible Signal - Intermittent
01435 - Brake Pressure Sensor 1 (G201)
35-10 - - - Intermittent

Thanks in advance

[Skydive@AI]

There's a seal in the torque converter that goes bad, and causes the lockup clutch to fail. You won't notice much except at highway speeds, but your torque converter needs a rebuild. You'll want to contact IPT, 2Bennet, 3Zero3 Motorsport, or my definite preference, 517 Transmission. Avoid Level10 like the plague.

[ChiTownAudi]

Am I doing damage by driving without the torque converter lockup ??.
Any idea of the cost. Dealership was $3,000 approx. at 150K I conserened about whats next to Go. Anyone have recommendations for a good Audi transmission shop in the Chicago-Land area