Code Definition

U0070 — Vehicle communication bus E negative Circuit low

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

About U0070

U0070 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 U0070 is stored, the module has detected a signal or supply voltage lower 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 U0070 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

This DTC is set when a control module detects that the voltage on the low side or negative circuit of the Bus E communication network is below the expected threshold. Bus E typically refers to a specific LIN or secondary CAN network depending on the vehicle architecture. A circuit low condition usually indicates a short to ground, excessive resistance, or a bus driver failure within a module. When this code is set the modules and devices on Bus E may lose communication, setting related U codes, illuminating warning lights, and leaving some features inoperative.

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