Hi I thought I posted this the other day but its not appearing.We had a 2004 206 with the same fault you describe no comms to ecu.What we found was a broken wire fro the bsi unit in the engine bay.From memory there are 2 looms nearest to the headlight the left hand one goes down through the inner wing.We disconnected it and pulled it down for better access and when we pulled on the individual wires one came apart.New piece of wire amd hey presto comms restored and engine started.