How Onboard Diagnostics (OBD) Work The Technology That Keeps Trucks Smart, Safe, and Efficient In the age of digital trucks, understanding Onboard Diagnostics (OBD) is no longer just for technicians—it's essential knowledge for fleet managers, exporters, and buyers of used Japanese commercial vehicles. OBD systems allow vehicles to self-monitor and report faults, helping prevent breakdowns, improve fuel efficiency, and simplify maintenance.