I have a 1997 Audi a8 Quattro that is slipping up a hill downshifting under 2k RPM. It does not slip above 2k RPM. It also hunts sometimes. There are no codes for the TCM. The dealer recommends a fluid and filter change and see if that improves the problems.
Therein lies the rub. Some of these auto trans hold vast amounts of fluids and the fluid is expensive. I suspect that a good chunk of the cost quoted by the dealer is made up by OE ATF. There's no getting around that issue unless you don't do a complete change (common) or you use the wrong fluid
It has 135,000 miles. The fluid was changed recently from the previous owner but the filter was not changed.
Changing fluid (and only a fraction of it probably) was a complete waste of time and $$, without changing the filter...infinitely more important than the fluid. When new fluid is introduced, it will only further clog an old filter when new detergents break loose even more debris. Plus, if filter wasn't changed, then the pan was not dropped and sludge removed...refilling could have also broken loose settled sludge, further clogging a filter that should have been changed.