I'm having a similar issue. Totally at random, the call simply wont start, it just turns over and over. Seems to be getting worse. 5-10 tries still no luck after 30 mins. Was at the point of phoning the AA and it started perfectly.
I was lucky enough to have
VCDS on my laptop in the car, plugged it in whilst tearing my hair out and caught this:
2 Faults Found:
17966 - Throttle Actuator (G186)
P1558 - 35-10 - Electrical Malfunction - Intermittent
16706 - Engine Speed Sensor (G28)
P0322 - 35-00 - No Signal
Readiness: 0000 0000
It looks like the Engine Speed Sensor has a problem - the result after I arrived home was:
2 Faults Found:
17966 - Throttle Actuator (G186)
P1558 - 35-10 - Electrical Malfunction - Intermittent
16706 - Engine Speed Sensor (G28)
P0322 - 35-10 - No Signal - Intermittent
Readiness: 0000 0000
I've garaged the car as I don't want to get stranded with an intermittent failure to start - is there something I can easily check, cable/connector wise? It feels like a dodgy connection but looking down at that packed engine bay I don't know where to look.
Any pointers appreciated.