Safe to driveDrivable, but watch it yourself
SPN 520721 is a manufacturer number outside the standard J1939 table: different makes can put different things under it. Below — how it is worded by International, and what the second half of the code (FMI) means.
| FMI 5 | Snow Plow Light Right Forward Lighting Relay Command — Right Plow Light Relay Under Current Or Open Circuit |
| FMI 6 | Snow Plow Light Right Forward Lighting Relay Command — Right Plow Light Relay Circuit Short To Ground |
| SPN 520721 FMI 5520721/5 · 520721.5 | current below normal or open circuit |
| SPN 520721 FMI 6520721/6 · 520721.6 | current above normal or grounded circuit |
Safe to drive. Below — how much time you have and what happens if you keep going.
This is an electrical fault: an open, a short or a bad contact in the sensor circuit. The value it measures is most likely fine.
You can drive. But until the circuit is repaired this system runs blind and cannot warn you about a real failure.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.