ISO 27145-3:2012

Overview - ISO 27145-3:2012 (WWH-OBD Common Message Dictionary)

ISO 27145-3:2012 defines a standardized common message dictionary for World‑Wide Harmonized On‑Board Diagnostics (WWH‑OBD) by specifying the implementation of a subset of Unified Diagnostic Services (UDS) from ISO 14229‑1. The standard describes how diagnostic services exchange the diagnostic data defined in ISO 27145‑2 between vehicle Electronic Control Units (ECUs) and external generic test equipment. The message set is independent of transport, network, data link and physical layers, and is intended to be used with ISO 27145‑4 (connection and protocol initialization), supporting both DoCAN and DoIP data links.

Key technical topics and requirements

• Subset of UDS services: Implements selected UDS service IDs (examples in the text include ReadDataByIdentifier (0x22), ReadDTCInformation (0x19), ClearDiagnosticInformation (0x14), RoutineControl (0x31)) tailored to WWH‑OBD regulatory needs.
• Protocol and application requirements: Defines application‑layer behaviour, addressing and timing requirements, message byte order, and handling of ECU response lengths.
• Independence from physical layers: Message semantics are transport‑agnostic; ISO 27145‑4 maps these services to DoCAN (ISO 15765 family) or DoIP (ISO 13400).
• Compatibility and data support: Includes provisions to support SAE digital annex data sets (SAE J1979‑DA, SAE J2012‑DA) and aligns with ISO 14229‑1 UDS semantics.
• Regulatory scope: Includes capabilities designed to satisfy OBD regulations across multiple regions, vehicle and engine types - but it does not interpret regional regulations or mandate applicability per vehicle/model year.

Practical applications

• Enables consistent communication between vehicle ECUs and external diagnostic/test equipment for emissions‑related OBD data.
• Supports development of generic off‑board diagnostic tools, vehicle test rigs, and validation suites that must interoperate across markets.
• Facilitates regulatory compliance testing infrastructure by standardizing message semantics used in WWH‑OBD GTR contexts.
• Useful for OEM software teams, diagnostic tool vendors, Tier‑1 suppliers, test laboratories and regulatory authorities who require a harmonized message dictionary.

Who should use ISO 27145-3

• Automotive OEMs and calibration teams implementing WWH‑OBD diagnostic interfaces.
• Diagnostic tool and scan‑tool manufacturers needing consistent UDS implementations.
• Certification and emissions test laboratories validating OBD behaviour across regions.
• Suppliers of ECU firmware and vehicle network integration specialists.

Related standards

• ISO 14229‑1 / ISO 14229‑2 (UDS specification and session layer)
• ISO 27145‑1, ISO 27145‑2 (general info and common data dictionary)
• ISO 27145‑4 (connection between vehicle and test equipment - DoCAN/DoIP)
• ISO 15765‑1/2/4 (DoCAN), ISO 13400 (DoIP)
• SAE J1979‑DA, SAE J2012‑DA, SAE J1930‑DA, SAE J1939 family

By standardizing UDS message semantics and mapping to SAE data sets, ISO 27145‑3 helps ensure interoperable, region‑agnostic diagnostic communication for modern vehicle OBD systems.