Safe to driveDrivable, but watch it yourself
J1939 code SPN 1078. Below — how the fault is worded at the factory by Ford Trucks, and what the second half of the code (FMI) means in the standard.
Ford Trucks/Ecotorq writes fault numbers in its own format: the code in the table below is a Ford code (hexadecimal, zero-padded), not a J1939 SPN. It matches the standard only where the signal itself is standard, and usually matches the title of this page by digit alone.
| FMI 3 | Vehicle supply voltage too high |
| FMI 4 | Vehicle supply voltage too low, wiring defective |
| SPN 1078 FMI 31078/3 · 1078.3 | voltage above normal or shorted high |
| SPN 1078 FMI 41078/4 · 1078.4 | voltage below normal or shorted to ground |
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.
Check the fuel filter and water trap, drain the water. In cold weather, suspect fuel waxing.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.