PRNDS flashing, doesn't switch gears

[delusional_A7_fan]

Hey,

I have Audi A6 C5 2.5TDI Quattro with automatic gearbox to begin with. I faced with some sort of transmission failure. All PRNDS is flashing, doesn't switch gears, always going on 1st gear, no matter how much I press the throttle it reaches 2.8k RPM and doesnt go more, poor acceleration. ( WHILE IN DRIVE, WHEN IN REVERSE OR NEUTRAL IT REACHES REDLINE). When I switch it to manual, the PRNDS light doesnt go away and isnt changing to 54321.

P.s sorry for probably many grammar mistakes, not a native speaker 😄

Any ideas what could it be ?

Chris.

Edited March 12, 2023 by delusional_A7_fan

[Steve Q]

I'd recommend a diagnostic check to see if any fault codes flag up. Could be an issue with the selector or module