Understanding OBD-II Engine Control Systems: Standards and Principles
•
By The GlobalTuningShop Engineering Team
The OBD-II (On-Board Diagnostics) standard is an integrated monitoring system present in all modern vehicles. This course explores its architecture, communication protocols, and its role in performance analysis.
System Architecture
The system relies on a network of sensors connected to the Electronic Control Unit (ECU). These sensors continuously monitor parameters such as airflow, temperature, and pressure.
- ECU (Engine Control Unit): The brain of the system, processing sensor data.
- CAN Bus (Controller Area Network): The main communication bus between modules.
- DLC (Data Link Connector): Standardized access point for reading codes.
Standards and Protocols
Several communication protocols coexist under the OBD-II standard, depending on the manufacturer and region.
Key technical documentation:
The ISO 15031 standard defines the technical requirements and service modes (1 to 9) for communication between the diagnostic tool and the vehicle.