U0001Network
CAN network · SAE
High-Speed CAN Communication Bus — Fault
Meaning
The control module that set this code is unable to communicate on the high-speed CAN bus (HS-CAN). The bus may be interrupted, short-circuited, or subject to electrical noise severe enough to prevent data exchange between modules.
Common causes
- Short circuit between CAN-H and CAN-L, or to ground/supply voltage
- Open circuit on one or both CAN-H/CAN-L wires
- Missing or open CAN termination resistor (120 Ω)
- Damaged bus wiring or connectors (corrosion, crushing, rodent damage)
- ECU/TCM/BCM with faulty CAN transceiver disturbing the bus
- External electromagnetic interference degrading the differential signal
Symptoms
- Multiple warning lights on simultaneously (ABS, SRS, engine, transmission, etc.)
- Control functions inactive or partially impaired
- Instrument cluster showing missing or frozen data
- Diagnostic scanner unable to communicate with one or more modules
- Possible vehicle immobilization in the event of total bus failure
Severity
Very high: loss of the main CAN bus can disable active safety systems (ABS, ESC, airbag); the vehicle must not be driven until the fault is resolved.
What to do
- Connect a diagnostic scanner and identify which modules are not communicating on the HS-CAN bus
- Measure the CAN bus termination resistance between CAN-H and CAN-L (expected approx. 60 Ω with both terminators in parallel)
- Inspect CAN bus wiring for short circuits, open circuits, and damaged or corroded connectors
- Use an oscilloscope to verify the CAN-H/CAN-L differential waveform for distortion or absent signal levels
- Identify and isolate any modules introducing bus disturbances; replace the faulty module or wiring segment