How to check if an A8 has servotronic, plus, where is the relay?

[MikkiJayne]

The valve on the D3 is still just a solenoid with no active trickery. The chip and circuitry in the D2 module is trivial to replicate in a body control module with a microcontroller though.

I don't think you'll find it as a discreet module in VCDS. It'll just be a sub-function of the body control module, and likely not even have anything to code or fiddle with, although it may throw a code if the solenoid is open circuit. The reduction in assistance will have been a software revision.

[Julian Thompson]

Agreed and thanks. So to summarise - d2 had the relay containing some processing. D3 did the processing in module J520 instead which connects directly to the valve on the rack.