Safe to driveTo the nearest safe stop
J1939 code SPN 667. Below — how the fault is worded at the factory by Ford Trucks and Mercedes-Benz, 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 0 | FAN Speed Sensor Electrical – Open / Short to Power. FODP code (scan tool): P0526-17. |
| FMI 1 | FAN Speed Sensor Electrical – Chassis Short Circuit. FODP code (scan tool): P0526-16. |
| FMI 3 | Starter Circuit (KL50) shorted to Ubat |
Safe to drive. Below — how much time you have and what happens if you keep going.
Fuel is not arriving in the right amount or at the right pressure. It shows up first on climbs and under load.
You will most likely stall out on the road, and may not restart on the shoulder. A clogged filter or water in the tank you can nurse to a shop; a failing injection pump you cannot.
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.
That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.
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.