Code Definition

U0421 — Invalid Data Received From Ride Level Control Module

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

About U0421

U0421 is a generic (obd-ii standard) network communication diagnostic trouble code recorded for Land Rover vehicles. 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 U0421 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 U0421 is set when a receiving control module determines that data received over the CAN network from the Ride Level Control Module is implausible, out of range, incorrectly formatted, or fails internal validity checks. The fault is logged when the message content does not align with expected suspension height values, status information, or timing requirements, even though communication with the module is still present. This condition indicates corrupted or unreliable ride height data rather than a total loss of communication.

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