SPN 625 FMI 9 — J1939 proprietary datalink lost
What it means: J1939 proprietary datalink lost.
How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.
Check first: Check terminations
Don't risk it — look up listed providers near you and give them this SPN/FMI when you call.
Listed providers nearest Indianapolis, IN
Closest first. Tell them SPN 625 FMI 9 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Indianapolis, IN · (317) 789-5002
- 0.0 mi away — based in Indianapolis, IN · (317) 300-7000
- 0.0 mi away — based in Indianapolis, IN · (317) 646-8208
Applies to: Navistar · Paccar · Volvo
What SPN 625 FMI 9 means
J1939 proprietary datalink lost.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Bus issue
- ECU offline
- CAN bus issue
- Another ECU offline
- Datalink issue
First moves (roadside)
- Check terminations
- Ping ECUs
- Ping all ECUs
- Scan all ECUs for presence
FAQ
J1939 proprietary datalink lost.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Bus issue. Other possibilities include ECU offline; CAN bus issue; Another ECU offline; Datalink issue.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside SPN 625 FMI 9, or share the same subsystem.
- ECU Power Supply — Intermittent / Erratic (SPN 627 FMI 2)
- Battery / Charging Voltage — Low (SPN 168 FMI 18)
- Engine Controller (ECM) — Internal Fault (SPN 629 FMI 12)
- Battery voltage low during crank (SPN 168 FMI 17)
- J1939 Data Link — Communication Error (SPN 639 FMI 2)
- High Speed CAN Bus Fault (U0001)
- Lost Communication with ECM/PCM (U0100)
- Lost Communication with Fuel Injector Control Module (U0105)
Same symptom: Lost communication
Other datalink faults. A U-code is a network problem and is diagnosed at the datalink, not at the module that went quiet.
- Lost Communication with TCM (U0101) · Electrical, Charging & Network
- Lost Communication with Gear Shift Module (U0103) · Electrical, Charging & Network
- Lost comms with ABS (U0121) · Electrical, Charging & Network
- Lost Communication with Body Control Module (U0140) · Electrical, Charging & Network
- Invalid Data from ECM (U0401) · Electrical, Charging & Network
- Invalid Data from TCM (U0402) · Electrical, Charging & Network
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.