Hi everyone!

I’m currently replacing my automatic transmission in my Audi A4 1998 2.8q and I have some issues. I got a great deal on an S4 transmission that had low mileage at low cost. Now that I have busted my budget just to install it. My mechanic told me that the transmission was the same but the electronic wasn’t. The car seems to work but after 100m the car fall in LIMP MODE and is stuck in second gear.
This is the only code that I am getting:
- 6182 Trans Input Speed Sensor (iss)

So my mechanic told me that the cables from my module do not communicate with the same parts in the transmission and that is my problem.
My question is, do I need to get a Trans Control Module from an S4 and all the wire and everything will work properly? Do I have anything else to think about? And does my Engine ECU will recognise my TCM if I change it for an S4 TCM?

Thanks for your help!