I've had the "AdBlue fault: no restart in X miles" warning come up recently on my SQ7.
My local VAG independent garage (who I trust) found a faulty NOx sensor (replaced) and a faulty AdBlue injector (replaced), but the problem still occurs.
Plugging in to the OBD-II port reveals error 09953 Reductant Quality Performance". I bought this batch of AdBlue from the dealer, it was well within its expiry date, and the garage has confirmed that the Urea levels are in spec.
We think there is a possibility of out of date firmware on the NOx sensor, which may also recalibration and is giving erroneous NOx readings.
Problem is that needs a specific VAG tool (Flash box VAS 601 011) which no-one except the main dealers seem to have - I've called 3 other independents so far with no luck. And none of the local dealers can fit me in for several weeks (when they actually answer the phone... I've tried 4).
Any ideas on where I might get this done? It's a 1 hour process. Or other ideas to check?
My best alternative right now is that I resort to using Vag-Com/VCDS to reset the AdBlue system whenever the error pops up, and hopefully buy myself sufficient miles to make it through to a dealer appointment.