Home › Land Rover › 2021 › Defender 90 First Edition › Repair and Diagnosis › General Information › Specifications Index › Diagnostic Trouble Code Index DTC: CHASIS Control Module (CHCM) -- Defender/L663 › Diagnostic Trouble Code Index - DTC: Chassis Control Module (CHCM) (G3139555) › Description And Operation › Chassis Control Module (CHCM) › DTC U0300-57: Internal Control Module Software Incompatibility - Invalid/incomplete software component › Possible Causes