SloopJohnB@mac.com

Looks more and more like a TCU issue. Ctrl/Alt/Delete works for you!
It could also be a connector issue at the TCU/harness connection. Try unplugging and reconnecting.

spoon2000

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Thank you. I will try unplugging and replugging. Or would leaving the battery disconnected for a couple hours accomplish the same thing?

On a side note, the airbag control module in the car will throw a code and cause the airbag warning light to illuminate when the temperatures get down into the 30s or 20s in the winter but I can go for months in the summer without ever having the warning come on (I have an airbag tool that will reset the module and turn out the warning light, and I've had the car long enough to know that it's definitely a temperature-related phenomenon) .

I'm not suggesting that the transmission and airbag module problems are related, but it does reinforce to me that odd things can happen to electronics when temperatures start to swing.

As the service writer I used to deal with at my local Ford dealership said one time when I had a power window switch that would sometimes cause the car's horn to honk briefly, "The automobile is the devil's own invention."

SloopJohnB@mac.com

plugging/unplugging can improve a bad connection....disc the battery is irrelevant and will just make you reset your radio code, LOL!

Airbag module not relevant to TCS/ABS AFAIK...the temp issue may well be with the coil connector behind the steering wheel but if it only does it in the summer, your choice to fix or not. Arguably, when the airbag light comes on the airbag won't inflate (reliably?) so your safety is your own concern. Don't go crying to Audi if you get in an accident and the airbag doesn't inflate.

spoon2000

Update... The car will now not move forward at all (only reverse). Boo. I unplugged the TCU and attempted to drive the car, but there was no change. I plugged the TCU back in and attempted to drive the car again, but still no forward gears. VCDS now displays code P0730 (without the word intermittent, as was the case when it showed P0733 originally).

I'm planning to have the car towed to the repair shop later today.

Any further advice?

SloopJohnB@mac.com

Sounds like you're doing the right thing getting it to the shop.

http://engine-codes.com/p0733_audi.html

provides a pretty good summary of things-that-go-wrong but it also doesn't cover the throttle position sensor (TPS) that can cause problems.

Time to let the shop sort it out. Hope you don't need a new transmission but that isn't out of the realm of possibility either. Your symptoms sound like what happened to our 2K4.2 at about 32K miles in 2002....the car eventually got a new transmission under warranty from Audi.

spoon2000

Heard back from the mechanic. Apparently all signs point toward the car needing a new transmission. TCU seems OK, fluid level is apparently fine, nothing is leaking. He mentioned that the cause could be the forward clutch drum or torque converter.

My mechanic says the only source they have for rebuilt transmissions is Audi, and he said sometimes parts and labor if they swap out the transmission for a rebuilt unit can run to near $10,000 (that seems absurdly high, and I suspect they just don't want to do the work). So he recommended that I look around for a dedicated transmission shop.

Any suggestions of places to go in the DC metro area?

And what SHOULD the job really cost between parts and labor?

Thanks.