Code Definition

U0071 — Vehicle communication bus E negative Circuit High

System: Network Communication  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About U0071

U0071 is a generic (obd-ii standard) network communication diagnostic trouble code. It belongs to the U-prefix family of codes, which covers inter-module network communication (CAN, LIN, FlexRay, or similar) faults.

When U0071 is stored, the module has detected a signal or supply voltage higher than the expected operating range.

Scanning & clearing: Network (U) codes report communication faults between modules. When diagnosing U-codes, checking the vehicle's CAN bus integrity, supply/ground at each module, and reading all modules for related faults is usually the first step.

Because U0071 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

DTC U0071 is a network communication code set when a control module detects that the voltage on the Bus E negative circuit, the low side of communication bus E, is higher than the specified range. Bus E is typically a secondary CAN or LIN network linking a subset of modules, and the negative line normally rests at a defined bias voltage and swings only within a narrow band during messaging. A persistently high voltage on this line suggests a short to a higher voltage source, an open or high resistance that disturbs the bias, or a module driver holding the line up. When this code is active the ...

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