i just bought an A6 2.5tdi with the CVT gearbox on test drive it appeared fine however driving it all weekend it seems to have a slight judder when changing gears especially when driving gently - when in tiptronic this problem is not apparent - when driven hard in auto the judder is worse almost like a misfire, i have read various horror storied on forums and do not wish to waste money at audi - how can i improve/fix/diagnose this problem and prevent any damage to car? will changing gearbox oil improve or worsen condition? please anybody reply with advice i am skint and not mechanical at all ;( thank you people - tip: DSG box much smoother

 

The CVT transmission is very unreliable. It usually breaks down and needs replacement around 100k.

1st thing is scan the transmission for codes.

2nd give the TCM a reset by disconnecting the battery for a couple of hours.

3rd change the transmission fluid and hope it helps.

When your gear selector is all highlighted, the PRNDS or PRND432 means its time for a rebuild or replacement.

 

ok sorry to be simple ...there are no warning lights yet - by codes do i need to plug into a diagnostic? 2. what is a TCM? many thanks

 

Yes a diagnostic. But a regular tool will not be able to communicate with the TCM (tranny control module). You will need a vag-com to scan the TCM for codes.

 

ok i did the diagnostic their were 3 faults found
18149 clutch pressure adaptation - limit reached - intermittent
18161 tiptronic switch (f189) implausable signal - intermittent
18226 - pressure control value 2 (n216) electrical malfunction - intermittent

they cleared codes test drove and then changed oil in gearbox - i drove car home and is now worse than before

 

Clear the codes and see which back. I think the TCU might need to be replaced. And correct me if im wrong, but i belive the TCU in the CVT is located inside the tranny. atleast, it is on the CVT a4.