Safe to driveTo the nearest safe stop
J1939 code SPN 3509. Below — how the fault is worded at the factory by Dongfeng, MAZ, Meritor (ex-WABCO), SITRAK and YaMZ, and what the second half of the code (FMI) means in the standard.
DongfengMAZMeritor (ex-WABCO)SITRAKYaMZ
| FMI 3 | Sensor No. 1 supply voltage too high. Effect: ECAS air suspension functions may be limited. |
| FMI 4 | Sensor No. 1 supply voltage too low. Effect: ECAS air suspension functions may be limited. |
| FMI 3 | Sensor supply 1 fault - Sensor supply voltage high. Blink code: 1-3-1. Power will be reduced. Repair: Check the harnesses and the sensors connected to the engine ECU. |
| FMI 4 | Sensor supply 1 fault - Sensor supply voltage low. Blink code: 1-3-1. Power will be reduced. Repair: Check the harnesses and the sensors connected to the engine ECU. |
| FMI 3 | Failure detection 'ShortUb' at SensorSupply |
| FMI 4 | Failure detection 'ShortGnd' at SensorSupply |
| FMI 2 | Sensor supply module 1 faulty. Scan tool code: P0643. Effect: Accelerator failure: engine speed limited to 1000–1500 rpm, torque to 1500 Nm. |
| FMI 5 | Undervoltage at sensor supply 1. Scan tool code: P0641. Effect: Torque may be limited. |
| FMI 6 | Overvoltage at sensor supply 1. Scan tool code: P0641. Effect: Torque may be limited. |
| FMI 13 | Over-temperature at sensor supply 1. Scan tool code: P0641. Effect: Torque may be limited. |
| FMI 3 | Sensor supply 1 fault (Sensor supply voltage high). Blink code: 1-3-1. Power will be reduced. Repair: Check the harnesses and the sensors connected to the engine ECU. |
| FMI 4 | Sensor supply 1 fault (Sensor supply voltage low). Blink code: 1-3-1. Power will be reduced. Repair: Check the harnesses and the sensors connected to the engine ECU. |
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.