O

OBD-II (On-Board Diagnostics II)
Standardized vehicle diagnostic port. 16-pin connector under dash. Provides access to: diagnostic codes, sensor data, CAN bus. Used for: vehicle data display on head unit, integration modules. → See also: CAN Bus
Chapter 5.5

OEM (Original Equipment Manufacturer)
Factory-installed equipment. OEM integration: preserving factory functions (steering wheel controls, backup camera) when adding aftermarket equipment. → See also: Integration
Chapter 5

Ohm's Law
Fundamental electrical relationship: V = I × R (voltage = current × resistance). Power: P = V × I = I² × R = V² / R. Foundation of all electrical calculations. → See also: Impedance, Power
Chapter 6.1