Home >> Land Rover >> 2021 >> Defender 90 X >> Repair and Diagnosis >> General Information >> Specifications Index >> Diagnostic Trouble Code Index DTC: Rear Differential Control Module (RDCM) -- Defender/L663 >> Diagnostic Trouble Code Index - DTC: Rear Differential Control Module (RDCM) (G2400909) >> Description And Operation >> Rear Differential Control Module (RDCM) >> DTC U0001-81: High Speed CAN Communication Bus - Invalid serial data received >> Possible Causes