What are OBD-II Trouble Codes? OBD-II (On-Board Diagnostics) trouble codes are alphanumeric codes generated by a vehicle’s onboard computer system. These codes provide valuable information about the vehicle’s performance and help technicians diagnose and fix issues. Introduction to Subaru OBD-II Trouble Codes Subaru vehicles, like many other modern cars, use the OBD-II system to monitor…