4 Universal HD diagnostic codes on file — with the full diagnosis, repair steps, and field insights open to read free, no signup required.
Disclaimer: General reference information for trained, qualified technicians only. Codes and procedures vary by model, serial number and software version. Always follow the manufacturer's service manual and your site's safety procedures. Use at your own risk. Not affiliated with or endorsed by any manufacturer.
| Code | System | Symptom | Full fix |
|---|---|---|---|
| SPN 1761 FMI 01 | Aftertreatment / SCR | Flashing DEF Lamp / Impending Speed Derate | View fix |
| SPN 3031 FMI 04 | Aftertreatment / SCR | DEF Warning Light / SCR Limp Mode | View fix |
| SPN 4364 FMI 18 | Aftertreatment / SCR | DEF Lamp Solid / 25% Engine Torque Derate | View fix |
| SPN 5246 FMI 00 | Aftertreatment / SCR | Speed Capped at 5 MPH (20 km/h) / Severe Derate | View fix |
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