ISO 14230-4 (KWP2000): A Guide to the OBD-II Communication Protocol

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ISO 14230-4, also known as KWP2000 (Keyword Protocol 2000), is an OBD-II communication standard developed for vehicle diagnostics. KWP2000 enables reliable data exchange between electronic control units (ECUs) and diagnostic tools, using serial communication and “keywords” to initiate data transfer.

How Does ISO 14230-4 (KWP2000) Work?

KWP2000 uses serial communication over the K-line, with FastInit and SlowInit methods available to establish a connection between the ECU and the diagnostic tool. The transmission speed can reach 10.4 kb/s, allowing reading and clearing of DTC codes, access to live data, and control of individual vehicle modules.

Launch OBD-II adapters that support the protocol:

DBScar I, DBScar II, DBScar III, DBScar IV, DBScar V, DBScar VII

ThinkDiag devices that support the protocol:

ThinkDiag, ThinkDiag 2

Ediag devices that support the protocol:

Ediag YA-101, Ediag YA-201, Ediag Plus, Ediag Elite

Vehicle types and brands supported by the protocol:

Passenger vehicles from European and Asian manufacturers, primarily Volkswagen, BMW, Mercedes-Benz, Audi, Honda, Toyota, Nissan, Mazda; models from 1996–2007.

Advantages of ISO 14230-4 (KWP2000)

  • Reliable and standardized communication for OBD-II diagnostics
  • Supports advanced diagnostic functions, including real-time sensor readings
  • Flexible for different types of vehicles and electronic modules
  • Compatible with various serial diagnostic tools

Disadvantages and Limitations

  • Lower transmission speed compared to modern CAN protocols
  • Requires additional configuration for FastInit and SlowInit initialization
  • Gradually becoming obsolete as newer vehicles transition to CAN and UDS standards
  • Compatibility may be limited with very new vehicle models

Applications of ISO 14230-4 (KWP2000)

KWP2000 is used for reading and clearing DTC codes, reviewing sensor data, module testing, and system resets. This protocol is particularly relevant for older and mid-aged vehicles that still use serial OBD-II communication.

Conclusion

ISO 14230-4 (KWP2000) is a key standard for understanding serial OBD-II diagnostics. While modern protocols gradually replace it, knowledge of KWP2000 remains essential for diagnosticians and technicians working with a full range of vehicles, especially older and mid-age models.