http://www.honestjohn.co.uk/forum/post/?t=66972 (try posting your question there as well)
from this site: http://www.topix.com/forum/autos/audi-a4/T9OUGDEHOVVF0G9B3
The following:
"EPC (Electronic Power Control) is your throttle valve, and your ESP (Electronic Stability Program) would come on because anytime you lose traction your ecm cuts back power by limiting your throttle by closing your throttle valve. You need to go to a certified dealer so that they can check the wiring between your throttle valve and the ECM. A garage cant do this because they don't know what wires are power and what are signal. If all wires and signals check out, you need a new throttle valve. If the wires don't check out, they need to find out if the wires are shorted or is the ECM giving incorrect information."
And some useful looking stuff to bookmark from here:
http://uk-mkivs.net/topic/4562-mk4-faqs-common-faults-please-contribute/
Walter, February 2015
