Diesel SPN/FMI Guide with OEM Sources
What SPN and FMI mean
In J1939 diagnostics, the SPN identifies a parameter or function and the FMI describes its reported failure mode. Record the reporting controller too. The code helps select a diagnostic procedure; it does not establish the failed part without testing. SAE J1939-73 — Application Layer: Diagnostics
One important distinction: 3226 is outlet NOx, 3216 is inlet NOx, and 1761 is DEF level. OEM fault-code numbers are a separate numbering system. Cummins SPN/FMI cross-reference — Atlas Copco
What to record before diagnosis
- Engine manufacturer, model, serial number and emissions generation.
- Full SPN/FMI, reporting controller and any separate OEM fault code.
- Active/inactive status, occurrence count and available freeze-frame data.
- Displayed lamps, restrictions and the conditions when the problem appeared.
A high occurrence count shows recurrence; it does not by itself prove a wiring fault.
FMI reference and limits
Use the FMI reference for common meanings and revision limits. A generic FMI definition is not evidence that every engine reports that FMI with every SPN.
Choose a documented code guide
Each guide identifies the scope of its examples. These are selected cases from published OEM material, not exhaustive code lists for every model year.
Scroll horizontally to see the sources.
| SPN | Guide | Evidence / scope in linked guide |
|---|---|---|
| 3226 | Outlet NOx | Cummins SPN/FMI cross-reference — Atlas Copco |
| 3216 | Inlet NOx | Cummins SPN/FMI cross-reference — Atlas Copco |
| 1761 | DEF level | Blue Bird SU2103 / Shaw 0000297252, revision B (2021) |
| 4364 | SCR conversion | Detroit 01 13-16 (January 2016) |
| 3364 | DEF quality | Blue Bird SU2103 / Shaw 0000297252, revision B (2021) |
| 3251 | DPF pressure; OEM measurement differs | Detroit 4 08-14 (April 2014) |
| 4374 | DEF pump speed | Detroit 5 21-14 (May 2014) |
| 1569 | Torque derate | Blue Bird SU2103 / Shaw 0000297252, revision B (2021) |
| 5246 | SCR inducement severity | Navistar IK0700115, Figure 2 (2021) |
| 641 | Turbo actuator; verify installed design | Cummins SPN/FMI cross-reference — Atlas Copco |
Choose the procedure by application
- Match the engine and calibration to the source procedure.
- Read related faults and establish which measurements are reliable.
- Separate the reported failure mode from the suspected physical cause.
- Use the OEM test conditions and verify the repair with the specified routine.
For example, turbo hardware varies, and DPF pressure parameters differ by OEM. Do not transfer a repair sequence solely because the SPN matches.
Remote diagnostic sessions
A compatible adapter such as Nexiq USB-Link 3 and a diagnostic laptop must be connected at the vehicle. Contact Torque Edge with the engine details to confirm software and connection requirements. If equipment is missing, we can discuss the setup before scheduling.
Sources and applicability
Source check: September 12, 2026. These are documented examples. Confirm the engine serial number, software calibration and current OEM instructions before using a test or repair procedure.
- SAE J1939-73 — Application Layer: Diagnostics — Standards reference. The full current Appendix A is not reproduced or certified by this guide; use the edition required for the vehicle.
- Cummins SPN/FMI cross-reference — Atlas Copco — 2013 ISX15, ISX12, ISL9 and ISB6.7; use only the applications marked in the source table.
- Blue Bird SU2103 / Shaw 0000297252, revision B (2021) — Specified Blue Bird Vision, All American and TX4 Cummins applications built after January 18, 2016; confirm header generation and part number.
- Detroit 01 13-16 (January 2016) — GHG14/GHG17 DD platform: 4364/18 and 4374/0; DDC-SVC-MAN-0084 and 0191.
- Detroit 4 08-14 (April 2014) — EPA07, EPA10 and GHG14: 3251/0, /1 and /16. Identify the monitored pressure parameter in the relevant section.
- Detroit 5 21-14 (May 2014) — GHG14 DD: 4374/0, pump speed compared with DEF pressure.
- Navistar IK0700115, Figure 2 (2021) — Bulletin covers specified 2016-and-newer B6.7, X15, L9 and A26 applications. Figure 2 is a historical OEM example, not a universal or current calibration schedule.
Frequently Asked Questions
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Start a remote diagnostic session
For a remote session, a compatible adapter such as Nexiq USB-Link 3 and a diagnostic laptop must be connected at the vehicle. Contact Torque Edge to confirm equipment, software and availability for your engine.
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