Safe to driveDrivable, but watch it yourself
J1939 code SPN 626. Below — how the fault is worded at the factory by International, and what the second half of the code (FMI) means in the standard.
| FMI 5 | Engine Start Enable Device 1 — Fuel Heater Relay Under Current Or Open Circuit |
| FMI 6 | Engine Start Enable Device 1 — Fuel Heater Relay Over Current |
| SPN 626 FMI 5626/5 · 626.5 | current below normal or open circuit |
| SPN 626 FMI 6626/6 · 626.6 | 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.