cchan

Weird, no issues here in my 9914S.
Does it make a difference if the car is off except for accessories, powered on but engine off, or engine running?
Could you perhaps power the V1 off another car or a wall source, then start up the 991 next to it and see if that causes X band to come on? Separate the cause from power source vs. something being emitted from the car.

WCE

When I used my V1 in my wife's Audi with their blindspot warning system it received a nearly constant low level rear K-band alert. (Audi's seem to be notorious for their narrow angle K-band emitters in the rear bumper resulting in sudden and constant high level K-band alerts just when you're overtaking...)
Anyway, went into the V1's programming mode and disabled rear K-band detection which cleared the issue!