Safe to driveEnough to reach the yard
J1939 code SPN 81. Below — how the fault is worded at the factory by Ford Trucks, Renault Trucks, SITRAK and ZF AS-Tronic, and what the second half of the code (FMI) means in the standard.
Ford TrucksRenault TrucksSITRAKZF AS-Tronic
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 | Fuel Pump Control Unit Electrical – Intermittent Connection. FODP code (scan tool): P0001-1F. |
| FMI 1 | Fuel Pump Control Unit Electrical – Open Circuit. FODP code (scan tool): P0001-00. |
| FMI 2 | Fuel Pump Control Unit Electrical – Internal High Temperature. FODP code (scan tool): P0002-00. |
| FMI 3 | Fuel Pump Control Unit Electrical – Short to Power. FODP code (scan tool): P0004-01. |
| FMI 4 | Fuel Pump Control Unit Electrical – Ground Short. FODP code (scan tool): P0003-01. |
| FMI 5 | Fuel Pump Control Unit Electrical – Short to Power. FODP code (scan tool): P0004-00. |
| FMI 6 | Fuel Pump Control Unit Electrical – Ground Short. FODP code (scan tool): P0003-00. |
| FMI 7 | Error Writing Injector-1 Code. FODP code (scan tool): P268C-00. |
| FMI 8 | Error Writing Injector-5 Code. FODP code (scan tool): P268D-00. |
| FMI 9 | Injector-3 Code Writing Error. FODP code (scan tool): P268E-00. |
| FMI 6 | Short to battery positive. Repair: Switch the ignition off, switch it on again and repeat the test. If the fault persists, replace the control unit. |
| FMI 0 | Particulate oxidation catalyst (POC) blocked. Scan tool code: P0000. Effect: Torque may be limited. |
| FMI 1 | Particulate oxidation catalyst (POC) removed. Scan tool code: P0000. Effect: Torque may be limited. |
| FMI 2 | Implausible POC differential pressure sensor signal. Scan tool code: P0000. Effect: Torque may be limited. |
| FMI 3 | POC differential pressure sensor voltage above the upper limit. Scan tool code: P0000. Effect: Torque may be limited. |
| FMI 4 | POC differential pressure sensor voltage below the lower limit. Scan tool code: P0000. Effect: Torque may be limited. |
| FMI 15 | POC differential pressure above the upper limit. Scan tool code: P0000. Effect: Torque may be limited. |
| FMI 17 | POC differential pressure below the lower limit. Scan tool code: P0000. Effect: Torque may be limited. |
| FMI 19 | POC differential pressure sensor signal error on the CAN bus. Scan tool code: P0000. Effect: Loss of communication with the modules, some functions are disabled. |
ZF AS-Tronic uses its own fault numbering: the number in the table below is an internal ZF code, not a J1939 SPN. It matches the title of this page by digit only and means something different.
| FMI 6 | Short circuit to positive supply on transmission brake valve Y1 output. |
Safe to drive. Below — how much time you have and what happens if you keep going.
Urea dosing is interrupted and the ECU is counting. First the lamp, then a torque cut, then a forced crawl speed — the stages come in by engine hours, not all at once.
The truck will not die mid-highway, but the window shrinks with every running hour. Plan the repair now, not when the power is gone: an emulator or "deleting AdBlue" does not remove the problem, the codes keep stacking.
That said, the manufacturer flags this code as critical — if in doubt, it is safer to stop and check on the spot.
Fill the AdBlue tank. If it’s already full, the problem is dosing or reductant quality — you need a scanner.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.