Component/System involved: Advanced Driver Assistance Systems â FSD (Supervised)/Autosteer (Lane Keeping Assistance) and Adaptive Cruise Control. Possible failure to warn/stop (FCW/AEB). Vehicle and data are available for inspection upon request. I preserved dashcam files and requested Tesla to preserve engineering logs and EDR. What happened & safety risk: On [XXX] at ~[XXX] PDT on [XXX] near East Palo Alto, CA, with FSD (Supervised) engaged, the system appeared to misinterpret an exit ramp/gore area as a continuing lane at a highway fork and maintained ~60 mph (posted ~70). As soon as I saw the trajectory was unsafe, I braked and began manual steering takeover, but the vehicle contacted a roadside sign near the gore/shoulder before I could complete the maneuver. I then stopped safely. No other vehicles were struck. Airbags did not deploy. This posed a serious collision risk to me, my passenger, and nearby traffic. Reproduction/confirmation: NOT REPRODUCED. I have not attempted to reproduce the event. UNKNOWN whether the issue has been reproduced by Tesla or a service center yet. Inspection to date: Police responded (report pending). My insurer has opened a claim. I opened a Tesla Service request asking to PRESERVE Autopilot/FSD engineering logs for the incident window and to coordinate EDR extraction; engineering review pending. Vehicle remains drivable. Warnings or symptoms before failure: No audible/visual forward-collision warning was perceived by me and I did not