Code Definition

U0284 — Lost Communication With Active Grille Air Shutter Module A

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

About U0284

U0284 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.

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 U0284 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

The vehicle control modules communicate over the Controller Area Network (CAN) to exchange engine thermal management and aerodynamic control data. DTC U0284 sets when one or more modules do not receive the expected CAN messages from Active Grille Air Shutter Module A within a calibrated time period. This indicates the module is not communicating, typically due to loss of power or ground, a CAN circuit fault, or an internal module failure. The active grille air shutter module operates the moveable grille vanes that open and close to balance engine cooling against aerodynamic drag, so when it is...

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