Safe to driveEnough to reach the yard
J1939 code SPN 4340. Below — how the fault is worded at the factory by Dongfeng and SITRAK, and what the second half of the code (FMI) means in the standard.
| FMI 3 | Short circuit to power or open circuit of urea heater 1. Scan tool code: P3032. Effect: In cold weather the SCR system cannot thaw. |
| FMI 4 | Short circuit to ground of urea heater 1. Scan tool code: P3031. Effect: In cold weather the SCR system cannot thaw. |
| FMI 2 | Over-temperature of the DEF line heater powerstage. Scan tool code: P20C1. Effect: Torque limited, the engine may shut down. |
| FMI 3 | Low-side short to battery on the DEF suction line heater. Scan tool code: P3032. Effect: In cold weather the SCR system cannot thaw. |
| FMI 4 | Low-side short to ground on the DEF suction line heater. Scan tool code: P3031. Effect: In cold weather the SCR system cannot thaw. |
| FMI 5 | Open circuit on the high side of the DEF suction line heater. Scan tool code: P3028. Effect: In cold weather the SCR system cannot thaw. |
| FMI 6 | Over-temperature on the low side of the DEF suction line heater. Scan tool code: P3081. Effect: In cold weather the SCR system cannot thaw. |
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.
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.