U122D00: Ethernet databus branch 2 no communication
Diagnostic trouble code U122D00 — what it means, the common
causes, and how to confirm the real fault before replacing parts.
What does U122D00 mean?
U122D00 indicates: Ethernet databus branch 2 no communication.
This relates to the Network / communication system.
Common causes of U122D00
Communication partner (control module on Ethernet data bus branch 2) is not responding
Faulty voltage supply to the communication partner
Faulty or damaged Ethernet cable on the affected branch
What to check (live data)
Voltage supply to the communication partner on Ethernet data bus branch 2
Parts often involved in U122D00
Ethernet cable (shielded or unshielded, 0.13 mm2 copper-magnesium alloy strands, white and green insulation)
Connector housings and contacts for Ethernet cables
Don't replace parts until the root cause is confirmed — many of these codes are caused by wiring, a connector or an upstream fault, not the part itself.
Get the confirmed root cause for U122D00 — on YOUR vehicle
A code is a symptom, not a diagnosis. AutoDX Pro cross-checks several
independent assessments, pinpoints the actual root cause, gives you the
exact tests to confirm it, and shows the parts — only after the cause is
confirmed. Reads your scan-tool photo and decodes your VIN with open
recalls.
U122D00 is a diagnostic trouble code: Ethernet databus branch 2 no communication.
What are the common causes of U122D00?
Common causes include: Communication partner (control module on Ethernet data bus branch 2) is not responding, Faulty voltage supply to the communication partner, Faulty or damaged Ethernet cable on the affected branch. The exact cause depends on the vehicle — confirm it before replacing parts.
Can I keep driving with U122D00?
It depends on the fault and your symptoms. Some causes are minor, others can damage components or affect safety. Get the root cause confirmed before deciding.
How do I fix U122D00?
Confirm the actual root cause with targeted tests first, then replace only the part that's at fault. AutoDX Pro gives you the root cause, the exact tests, and the parts for U122D00 on your specific vehicle.