Good ay everyone. I have been troubleshooting my parking assist after installing a new infotainment system in my 2017 R. I solved the issue i was having with the system coming on line before the head unit is ready. This gave a parking assist not available warning on every start up. My parking assist front sensor like most here do not come on automatically and the manual function button has never activated them. I have discovered, at least on my car, if I bump the car into neutral while on under the parking sensor cutoff speed they activate and work as they are expected too. I have been doing this foe a week or so in different situations and they have worked every time. As always with our cars your mileage may vary but this may work for others out there.