Help please. Our 2006 Sport will not shift above 3rd gear in automatic mode ( "D"), however I can put it in Sport, then put it back into Drive and it will shift to 4th, but stay now in 4th, and I can do it again and it will shift to 5th, and doing it again will let it go to 6th. I can also put it in Sport Mode then manual and shift up and down manually through all the gears, it just will not do it in D mode. Any thoughts?

Check tyre wear across the axles

Sometimes the different running circumference will stop the autobox shifting above 3rd.

Failing that you need a fluid change....

Failing that the box may be toast.. RRS gone
Audi SQ5...Gone Audi Q7 S-Line 240 3.0TDI Gone
Audi A6 Allroad Sport 270 3.0TDI