Gearbox failsafe mode when cold

[alastair4151]

On my C5 RS6 the gearbox often goes into failsafe mode when the car is cold and been sitting unused for a few days.At the moment temperatures are hovering around the freezing mark.When you turn the car off again and restart it it is fine.The initial "clunk" which you often get in auto cars when gearboxes are cold seems to set it off to go into failsafe.Is this normal,and should you let the car warm up for a few minutes when driving off,and shifting into gear? Also I was going to get the oil changed in the gearbox,but my local Audi dealer says the gearbox on these cars are sealed and not serviceable.This made me think if this is true as my 1998 S8 which I think has an identical gearbox had its fluid changed 5000 miles ago.

[lswing]

It's "easy" to replace the filter and fluid, here is the manual in link below, take it to your dealer. Personally I would find a different shop since they gave you a line of BS.

http://audirssix.com/index.php/extras

Could be fluid is thick since cold, along with old filter not flowing well, causing the clunking. Valve body could just be sticky from old/cold fluid too.

Sometimes when new fluid is put into an old trans, that's never been changed, you will get the dreaded clutch slip as it seems the new fluid doesn't have all the particles and gunk to help keep the clutches together...although most of it is just original wear showing and it was going to fail anyhow.

Be careful, the trans can be anywhere from $4-8k parts/labor if it fails.

Edit; the trans is listed as "lifetime fluid", so that could be where the dealer gets non-serviceable. But they should know better, and this is one of the simplest procedures to be done. Try and find a mechanic who has worked on an RS6.

[Aronis]

I have had my transmission serviced three times.
68,000 miles 2008, new seal since it was leaking, thus new fluid
102,000 miles 2010, new torque converter, new fluid
140,000 miles 2016, new input and output seal, with pan seal, and new fluid

So I think if you got 100,000 with the original fluid than the 'old fluid viscosity with junk in it' theory makes perfect sense. But if it gets routine fluid changes over the life of the transmission, no harm will be done. To me it makes more sense to spend the money on routine transmission service so at least 1. the fluid is LOOKED at periodically, 2. the screen is looked at for worn part pieces, 3. new Seal is nice to hopefully avoid unplanned leak. 4. be certain levels are correct. I am not sure the logic behind "don't ever open that box, UNLESS it fails." Sounds more like creating a hazard for the second owner of the car????

Mike

Just jinxed my transmission didn't I?

[lswing]

I fully agree with Mike's statements regarding the fluid changes, good points. I've just heard of more than a few transmissions that have never been serviced, get serviced, then fail; but they were probably getting serviced because they were about to fail, sort of like what may be going on here...that's not convoluted is it?

Good luck! Oh yes, service should be around $400 parts/labor with fluid, filter, and time. Make sure they follow the correct fill process, and then check levels a week later!

[Bigglezworth]

On my C5 RS6 the gearbox often goes into failsafe mode when the car is cold and been sitting unused for a few days.At the moment temperatures are hovering around the freezing mark.When you turn the car off again and restart it it is fine.The initial "clunk" which you often get in auto cars when gearboxes are cold seems to set it off to go into failsafe.Is this normal,and should you let the car warm up for a few minutes when driving off,and shifting into gear? Also I was going to get the oil changed in the gearbox,but my local Audi dealer says the gearbox on these cars are sealed and not serviceable.This made me think if this is true as my 1998 S8 which I think has an identical gearbox had its fluid changed 5000 miles ago.

What do you mean by "failsafe"? Do you mean the multitronic dash indicator lights up solid? Have you scanned for any trouble codes?