Safe to driveTo the nearest safe stop
J1939 code SPN 3383. Below — how the fault is worded at the factory by DAF, and what the second half of the code (FMI) means in the standard.
| FMI 3 | AdBlue tank heater short to power supply/open circuit at ECU pin A21/A11 |
| FMI 4 | AdBlue tank heater short to ground at ECU pin A21 (extended period) |
| FMI 16 | AdBlue tank heater signal voltage too high at ECU pin A21 |
| FMI 18 | AdBlue tank heater signal voltage too low at ECU pin A21 (extended period) |
Safe to drive. Below — how much time you have and what happens if you keep going.
The electrical system is not holding voltage. While the engine runs the alternator carries it; shut it off and you may not restart.
Next the lights go, then modules start dropping out and false codes appear all over the truck. Get to somewhere with help without shutting the engine down.
Check the battery terminals and earth strap — corrosion and loose clamps throw false codes all over the truck. Running voltage should be 27–29 V.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.