2012 Versa 1.6 sedan 90,000 miles. Ran perfectly fine. One day it would not start. Cranks great but will not start. Absolutely no check engine lights or codes.  There is no spark but the coils are getting 12v.  My mechanic has confirmed fuel, fuel pressure, good compression, crank/cam signals.  He thinks it might be a bad ecu. Is there a way to confirm this? Any other thoughts?  Its been at the shop for 2 months now.  This is far above my level of knowledge and even has my trusted mechanic stumped.  It has never been in an accident, regular maintenence has always been performed, I purchased it brand new and it ran perfectly fine before this.  No signs whatsoever of running rough or other issues. Thanks!