I may have been obtuse. The "no DTC" just referred to no fault codes registered at that time. I have had the usual minor component issues come up in my ownership and at the time they registeded a fault, which was then fixed. Happy to look further into the torque monitoring thresholds and that could tie in with the ESP light. Clearly, a new tune from scratch is one approach that would clarify some issues. I would have started that process if I wanted any more power but I'm happy with the standard power level and can fall back on the manual RS4 if I want more power.