The millimeter wave radar has failed. While using adaptive cruise control the vehicle set off many alarms without prior warning. The vehicle suddenly showed that adaptive cruise control, lane keeping, road departure mitigation, frontal collision, low speed parking were no longer functioning and to see a dealer. I was not using frontal collision no road departure mitigation as these features had twice before unexpectedly applied heavy breaking without warning with no obstructions near vehicle. Fortunately no accident occurred but very unnerving to say the least. The dealer has confirmed that the millimeter wave radar has failed and will need replaced. Honda sensing is not very reliable and should be used with caution if used at all