Diagnostic trouble code U005600 — what it means, the common
causes, and how to confirm the real fault before replacing parts.
What does U005600 mean?
U005600 indicates: Vehicle Communication Bus D Performance.
This relates to the Network / communication system.
Common causes of U005600
Short circuit between CAN-high and CAN-low
Short circuit between CAN-high and positive voltage
Short circuit between CAN-high and Ground
Short circuit between CAN-low and Ground
Short circuit between CAN-low and positive voltage
Open circuit in CAN-high data path
Open circuit in CAN-low data path
Malfunctioning control module causing data bus fault symptoms
Fatal errors detected in affected control module causing it to disconnect from bus (bus OFF) at least twice
Message timeout triggered when at least 10 consecutive messages are not received
What to check (live data)
Gateway measuring value blocks (via VAS scan tool, Address Word 19 on later Audi models, Address Word 17 on earlier models)
CAN-bus continuity check using ohmmeter (Drivetrain CAN)
DSO voltage on CAN-high wire (Channel A)
DSO voltage on CAN-low wire (Channel B)
Parts often involved in U005600
CAN-high wiring
CAN-low wiring
Control modules connected to the data bus
Gateway control module
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 U005600 — 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.
U005600 is a diagnostic trouble code: Vehicle Communication Bus D Performance.
What are the common causes of U005600?
Common causes include: Short circuit between CAN-high and CAN-low, Short circuit between CAN-high and positive voltage, Short circuit between CAN-high and Ground, Short circuit between CAN-low and Ground. The exact cause depends on the vehicle — confirm it before replacing parts.
Can I keep driving with U005600?
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 U005600?
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 U005600 on your specific vehicle.