U0122 — Lost Communication with Vehicle Dynamics Control Module
What it means: Lost Communication with Vehicle Dynamics Control Module.
How serious / can you keep driving: Caution. Limp to the next safe stop.
Check first: Check VDC module power and CAN connections
Don't risk it — look up listed providers near you and give them this code when you call.
Listed providers nearest Sparks, NV
Closest first. Tell them U0122 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 Sparks, NV · (775) 355-6884
- 0.0 mi away — based in Sparks, NV · (775) 356-7200
- 0.0 mi away — based in Sparks, NV · (775) 359-0550
Seen on: Heavy Truck
What U0122 means
Lost Communication with Vehicle Dynamics Control Module. Common causes: VDC/stability module offline.
How serious is it?
Caution. Limp to the next safe stop.
Most likely causes
- VDC/stability module offline
- Module power fault
- CAN wiring
First moves (roadside)
- Check VDC module power and CAN connections
FAQ
Lost Communication with Vehicle Dynamics Control Module. Common causes: VDC/stability module offline.
Caution — Limp to the next safe stop.
The most common cause is: VDC/stability module offline. Other possibilities include Module power fault; CAN wiring.
Limp to the next safe stop. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside U0122, 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 proprietary datalink lost (SPN 625 FMI 9)
- J1939 Data Link — Communication Error (SPN 639 FMI 2)
- High Speed CAN Bus Fault (U0001)
- Lost Communication with ECM/PCM (U0100)
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 Fuel Injector Control Module (U0105) · Electrical, Charging & Network
- 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
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.