satsingh2015

HI
Hoping someone can advise with this query. I have a 2005 Audi A8 3.0tdi quattro and the management light came on while driving it. As I was stuck in traffic I noticed the car was letting out a lot of white smoke from the exhausts and after getting it checked the mechanic confirmed it has a EGR problem.
I have now replaced the EGR with a new genuine EGR valve and the smoking seemed to have stopped until I took it on the motorway and noticed it was still smoking. Got it checked again and computer shows EGR flow error again.
Mechanic checked the inlet manifold and confirmed they are both badly clogged up with carbon. Could this be causing the smoking issue? I can either get the manifold cleaned by hand or someone has told me about TerraDiesel. Can someone please advise if TerraDiesel could clear out the carbon and solve the smoking issue?
Thanks