SAE J1939-71-2025 PDF

Full title and description

St SAE J1939-71-2025 — Vehicle Application Layer. This SAE J1939 technical standard (J1939/71_202502) specifies the application-layer parameter (SP) and message (PG) definitions, data encoding (SLOT) conventions, text-data conventions, and PG transmission-rate conventions used for J1939 vehicle networks; it serves as the reference for SPNs and PGNs used by ECUs on heavy-, medium- and light-duty vehicle networks.

Abstract

SAE J1939-71 (revised February 25, 2025) defines the Vehicle Application Layer for the SAE J1939 family: formal SPN (Suspect Parameter Number) and PGN (Parameter Group Number) definitions, parameter placement and scaling, standard transmission rates, and conventions for text and multi-byte encodings. Many of the application-layer data elements that were historically included in this document are also published in the J1939 Digital Annex (J1939DA) for searchable/digital access.

General information

• Status: Revised (current revision published February 25, 2025).
• Publication date: February 25, 2025.
• Publisher: SAE International.
• ICS / categories: Road vehicles — Electrical and electronic equipment (ICS 43.040.10); vehicle communication protocols and diagnostics.
• Edition / version: J1939/71_202502 (revised edition, February 2025).
• Number of pages: 40.

(Core bibliographic and revision details per SAE mobilus catalog.)

Scope

Defines the SAE J1939 application-layer reference for use across on- and off-highway light-, medium- and heavy-duty vehicles and appropriate stationary applications using vehicle-derived components. The document standardizes SP/PG definitions, data encoding and placement in PG payloads, transmission-rate conventions, and text-parameter conventions to enable interoperable ECU communications on J1939 CAN-based networks. It is one part of the broader J1939 family; industry- and diagnostic-specific messages may be documented in other J1939-7X documents.

Key topics and requirements

• Canonical listing and formal definitions of SPNs and PGNs (parameter and message identifiers) used on J1939 networks.
• Standard data encoding and SLOT definitions: byte positions, lengths, scaling and offsets for parameters within PG payloads.
• Transmission-rate conventions and default priorities for PGs (broadcast vs destination-specific behavior).
• Conventions for text/string parameters and multi-byte parameter encodings.
• Guidance on coexistence with other J1939 documents (digital annex, diagnostics, network management) and migration of data into the J1939DA digital annex for searchable access.

Typical use and users

Used by vehicle OEMs, ECU/module suppliers, telematics and diagnostic-tool vendors, integrators and system architects to implement and interpret J1939 application-layer messaging. Also used by firmware engineers, test and validation teams, service/maintenance organisations, and third-party tool vendors who decode PGNs/SPNs, implement message transmit/receive behavior, or map vehicle parameters for displays, logging or telematics.

Related standards

Part of the SAE J1939 family and commonly used with the following documents and reference standards: J1939/21 (Data Link Layer), J1939/11 and J1939/15 (physical layers), J1939/81 (Network Management), J1939/73 (Diagnostics), the J1939 Digital Annex (J1939DA — digital SP/PG listings), and underlying CAN specifications such as ISO 11898-1 (29-bit extended frame format). These adjacent documents define the lower-layer framing, physical interfaces and network-management/diagnostic behaviors that J1939-71 assumes.

Keywords

SAE J1939, J1939-71, Vehicle Application Layer, PGN, SPN, Parameter Group Number, Suspect Parameter Number, CAN, ISO 11898-1, Vehicle networking, ECU, diagnostics, J1939DA.

FAQ

Q: What is this standard?

A: SAE J1939-71 (Vehicle Application Layer) is the J1939-family technical standard that lists and defines application-layer message structures (PGNs) and parameters (SPNs), how parameters are encoded in PG payloads, and conventions for transmission rates and text/data encodings on J1939 vehicle networks.

Q: What does it cover?

A: It covers formal SPN/PGN definitions, byte/bit placement and SLOT encodings, scaling and offsets for parameters, default transmission rates and priorities, and conventions for text parameters — enabling consistent interpretation and generation of application-layer messages across J1939 implementations.

Q: Who typically uses it?

A: Vehicle OEM engineers, ECU suppliers, telematics and diagnostic-tool vendors, firmware developers, integrators and service/maintenance organizations who need an authoritative reference for PGN/SPN definitions and application-layer behavior on J1939 CAN networks.

Q: Is it current or superseded?

A: The edition referenced here is the revised SAE J1939/71_202502 published February 25, 2025 (status: Revised). Users should confirm the revision date for their use-case and check for any later errata or subsequent revisions published by SAE International.

Q: Is it part of a series?

A: Yes — it is one document in the SAE J1939 family of recommended practices and technical standards (J1939/11, /12, /15, /16, /21, /31, /71, /73, /81, etc.). Many implementations rely on multiple J1939 documents together.

Q: What are the key keywords?

A: PGN, SPN, parameter group number, suspect parameter number, application layer, J1939, CAN, ISO 11898-1, vehicle network, ECU, diagnostics, J1939DA.