J1979-2_202604: E/E Diagnostic Test Modes: OBDonUDS

Features

Issuing Committee: Vehicle E E System Diagnostic Standards Committee

Scope

Content

SAE J1979-2 describes the communication between the vehicle’s OBD systems and test equipment required by OBD regulations. OBD regulations require passenger cars and light-, medium-, and heavy-duty trucks to support a minimum set of diagnostic information to external (off-board) “generic” test equipment.

To achieve this, SAE J1979-2 is based on the Open Systems Interconnection (OSI) Basic Reference Model in accordance with ISO/IEC 7498-1 and ISO/IEC 10731, which structures communication systems into seven layers. When mapped on this model, the services specified are broken into:

Diagnostic services (layer 7), specified in:
- ISO 14229-1
- SAE J1979-2 OBDonUDS
Presentation layer (layer 6), specified in:
- SAE J1930, SAE J1930DA
- SAE J1979DA
- SAE J2012, SAE J2012DA
- SAE J1939DA, SAE J1939-73
Session layer services (layer 5), specified in:
- ISO 14229-2
Transport layer services (layer 4), specified in:
- DoCAN: ISO 15765-2 Transport protocol and network layer services
- ISO 15765-4 Requirements for emissions related systems
- DoIP: ISO 13400-2 Road vehicles - Diagnostic communication over Internet Protocol (DoIP) - Part 2: Transport protocol and network layer services
Network layer services (layer 3), specified in:
- DoCAN: ISO 15765-2 Transport protocol and network layer services
- ISO 15765-4 Requirements for emissions related systems
- DoIP: ISO 13400-2 Road vehicles - Diagnostic communication over Internet Protocol (DoIP) - Part 2: Transport protocol and network layer services
Data link layer (layer 2), specified in:
- DoCAN: ISO 15765-4, ISO 11898-1, ISO 11898-2
- DoIP: ISO 13400-3 Road vehicles - Diagnostic communication over Internet Protocol (DoIP) - Part 3: Wired vehicle interface based on IEEE 802.3

Physical layer (layer 1), specified in:

DoCAN: ISO 15765-4, ISO 11898-1, ISO 11898-2, in accordance with Table 1

DoIP: ISO 13400-3 Road vehicles - Diagnostic communication over Internet Protocol (DoIP) - Part 3: Wired vehicle interface based on IEEE 802.3

NOTE:

SAE J1979-2 provides a STANDARD to satisfy known country-specific OBD regulations. SAE J1979-2 is not considered a final authority for interpretation of the OBD regulations, so users of this document should determine the applicability of capabilities defined in this document for their specific OBD regulatory requirements.

Details

Citation: SAE International Technical Standard, E/E Diagnostic Test Modes: OBDonUDS, SAE Standard J1979-2_202604, Revised April 2026, Issued April 2021, .

Additional Details