I've had my RS6 for some 3 years. Put up 20,000 km in mainly lond distance driving in that time despite pandemic travel restrictions. Totally trouble free with two exceptions. In Nov 2020 I overtook a multi trailer truck and pulled back in and re-engaged cruise. EPC and ABS light came on, engine lost all power and went into limp mode. On coming to a stop, the engine was ideling at above 1000 RPM and seemed quite noisy but not mechanical noise. Re-started engine and all warning lights were out and car was totally normal in sound and performance. I did not however use cruise again that day. Checked faults at first stop and none registered. The car then performed totally normally with a lot of brisk accelleration activity in exactly the same scenerio for 15 months and 14,000 Km.

Earlier this week in exactly the same situation immediately after overtaking a multi trailer truck, the ESP light came on and the engine went into limp mode. As I was at speed and the truck was close I managed to pull over before killing the engine, I only saw the ESP light but others may have come on. The first time I ideled for some time trying to assess the problem, this time it was an immediate shut down as I was aware that it worked on the previous occasion. Same outcome, re-start and it ran perfectly. Completed the days journey without cruise, maybe another 400 Km. Again no fault codes.

I have read up on many posts about this general sort of problem but none seem to have not had a fault code or a frequent re-occurance of the problem. The actual symptoms were identical in overtaking at speed, re-engage cruise, engine immediately goes into limp mode with no power. The differences were EPC and ABS lights first time and possibly only ESP light second time. Currently the car is running like a train, you wouldn't know that some fault is lurking ready to pop out at some time in the future.

With very little to go on and no codes, has anyone heard of similar? My RS4 gets equal treatment and has never thrown a light in nearly 9 years.