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TuningBot DTC Database · v4.37.15

U0004 Controller area network (CAN) data bus: high speed bus(+) - voltage low

Generic (OBD-II) interpretation in the TuningBot DTC database.

U · NetworkNetworkOBD2

What U0004 means

U0004
Controller area network (CAN) data bus: high speed bus(+) - voltage low Generic · network Data confidence 65%

The control module detected that the Controller area network (CAN) data bus: high speed bus(+) voltage stayed below the expected range.

Symptoms

  • Multiple systems may log communication codes
  • Possible loss of gauge or system functions

Possible causes

  • Bus wiring open or short circuit
  • Terminating resistor fault
  • A faulty node disturbing the bus
  • Connector corrosion

Recommended checks

  • Measure CAN-H/CAN-L voltages and bus resistance
  • Map communicating vs silent modules with a full scan
  • Inspect harness sections prone to chafing
  • Check for water ingress at connectors

Related and nearby codes

U00 range
U0001U0002U0003U0005U0006U0007U0008U0009U0010U0011U0012U0013U0014U0015U0016U0017U0018U0019

How to read U0004

U

Network: communication between control units.

0

Generic SAE-standard code: same meaning on every make.

004

Specific fault index within the subsystem.

Frequently asked questions about U0004

What does U0004 mean?

Controller area network (CAN) data bus: high speed bus(+) - voltage low. The control module detected that the Controller area network (CAN) data bus: high speed bus(+) voltage stayed below the expected range.

Is U0004 generic or manufacturer-specific?

U0004 is a generic OBD-II code: it has the same meaning on every make and model that follows the SAE standard.

Can TuningBot remove U0004 at file level?

Not guaranteed. Powertrain (P) codes can be reliably disabled in the ECU calibration, but body, chassis and network codes depend on the specific control unit and how the fault is implemented - some can be handled, some cannot. Ask for a quote and our engineers will check your file and tell you, free of charge, whether U0004 is removable in your case.

Other file services

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