Have you ever worked on a car? OBD standards literally only require emissions controls to be openly diagnosed. The rest of the CEL codes can 100% be vendor spe

Have you ever worked on a car? OBD standards literally only require emissions controls to be openly diagnosed. The rest of the CEL codes can 100% be vendor specific. So when your body control module shits out, and you can't lock and unlock your doors anymore, you're fucked. When your ABS light comes on, and all you need to do is replace a $10 wheel speed sensor, you still need an expensive proprietary code reader to read the codes. "OBD II is an acronym for On-Board Diagnostic II, the second generation of on-board self-diagnostic equipment requirements for light- and medium-duty California vehicles. On-board diagnostic capabilities are incorporated into the hardware and software of a vehicle's on-board computer to monitor virtually every component that can affect emission performance. " Yes a lot of the primary engine functions affect emissions, but the majority of diagnostic codes on modern cars are not available to standard OBDII readers. Once you get outside of the engine, forget it. Every module in modern cars now is VIN-locked and can only be swapped in by a dealer, or some kind of cracked 3rd party software if you're lucky.