I have a 09 g8 gt I got the infamous contact dealer light also engine light car goes into limp mode I hooked my code reader up and got u0073,p2544,p0700,u0101,I got the u0073 3 times and p0700 twice. sometimes it wont start so I disconnect the battery wait 10 mins and it starts sometimes its completely stock .I've looked throughout the fourm and everyone that seems to find out the problem never responds help me help myself and the next person who's gonna deal with this on going issue
Looks like it could be a wiring issue... Seeing as how you're getting messages about the BUS not being able to communicate properly. IS there a harness related to all of those items? IT's highly unlikely all those parts would fail at once unless they're connected to some common element, possibly the ECM?
Thanks alot for your feed back when I wiggle the wire going into the fuse box it will start and sometimes they all go away but if I make a wide turn all hell breaks loose and ita back to limp mode. But I'll check out the tcm