Code Definition

U0420 — Invalid Data Received From Power Steering Control Module

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

About U0420

U0420 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 U0420 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

Control modules on the high speed CAN bus continuously exchange data with the power steering control module to coordinate steering assist and stability functions. DTC U0420 is set when a receiving module determines that the messages from the power steering control module are present but contain invalid, implausible, or out of range values that do not match expected parameters. Unlike a lost communication code, the module is still transmitting, so the fault usually points to the power steering module operating incorrectly, corrupted internal or calibration data, an unstable power supply, or CAN...

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