Took the RS6 back down to Harding Performance on the 11th to have a look at the ECU/TCU communication issues.
Plugging their VCDS into the car revealed codes which it’s never had before –
01119 – Gear Recognition Signal
35-10 – Intermittent
01315 – Transmission Control Module
49-10 – No Communications – Intermittent
Report back from HP was that they “removed the trans ECU and inspected the loom and connector and all was fine. They also double checked the solder connections and there we no visible signs of a bridge or a dry joint. Ran over the connections again with the soldering iron and ensured they were all ok. Reinstalled into the car and test drove without any problems.”
It’s been back on the road for a week or so now and it has not kicked any of the fault codes. Here’s hoping that it’s fixed.