Vehicle diagnostic protocol for monitoring the emission-related systems of a motor vehicle. Also called OBD-II. EOBD is the European counterpart to OBD-2 (OBD-II). Of particular importance here are exhaust gas recirculation (EGR), catalytic cleaning (catalytic converter) with the aid of the lambda probe and installed particulate filters (e.g. DPF).

OBD-2 uses a 16-pin connector to connect a diagnostic system to the vehicle. Although the presence of this connector is mandatory for OBD-2 compatibility, it is not possible to infer an implemented OBD-2 protocol from the connector.

All passenger cars from 2008 onwards and all motorbikes from 2017 onwards (exhaust emission standard EU4, EU5 and newer) use can with ISO15765 protocol for OBD-2 diagnosis. Earlier vehicles mostly use K-Line , more rarely VPW or PWM.

Many manufacturers use the obd-2-plug in the vehicle (also) for the manufacturer's own OBD. OBD-2 protocol and manufacturer's own diagnostics do not necessarily have to use the same physical connection. A 2006 VW Golf, for example, uses CAN Bus for the manufacturer's own diagnostics but K-Line for OBD-2.

It is important to know that the OBD-2 diagnostic protocol does not offer the diagnostic depth of the manufacturer's own diagnostics. If possible, diagnostic software that supports the diagnostic protocols of the respective vehicle manufacturer should be used.

Diagnostic software and diagnostic hardware (complete kit) using OBD-2: OBD2 Diagnostic kit

FAQ regarding OBD and OBD2: OBD FAQ

Info about OBD-2 as protocol: California Air Resources Board (CARB)