13 Universal 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.
Find a Universal code by searching below, or browse the table. Codes on file by system:
| Code | System | Symptom | Full fix |
|---|---|---|---|
| P0420 | Emissions | Check Engine / High Fuel Use. | View fix |
| P0A0F | Hybrid / EV | No Start. The vehicle powers on but the engine/motor fails to engage. | View fix |
| SPN 110 FMI 15 | Cooling | Fan Running 100% / Warning. | View fix |
| SPN 1569 FMI 31 | Engine | Low Power / Derate. | View fix |
| SPN 168 FMI 4 | Electrical | Ghost Faults / No Starts. | View fix |
| SPN 3031 (FMI 3) | Exhaust (SCR) | MIL Lamp / Derate Imminent. | View fix |
| SPN 3031 (FMI 4) | Exhaust (SCR) | MIL Lamp / Cold Start Issues. | View fix |
| SPN 3241 / 4360 FMI 16 | Exhaust | Regen Required / High Heat. | View fix |
| SPN 3360 FMI 10 | Exhaust | DEF Pump Failure. | View fix |
| SPN 3364 (FMI 2/17) | Exhaust (SCR) | MIL Lamp / 5-MPH Derate. | View fix |
| SPN 3607 FMI 2 | Engine Control | Engine Won't Stop / Erratic Idle. | View fix |
| SPN 639 FMI 9 | Network | Dashboard "Blackout" | View fix |
| SPN 639 FMI 9/14 | Network | Dash is a "Christmas Tree." | View fix |
Same codes keep coming back?
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