Home >> Land Rover >> 2021 >> Defender 90 X >> Repair and Diagnosis (Single Page) >> Quick Lookups >> Common Specs & Procedures >> Diagnostic Trouble Code Index DTC: Transmission Control Module (TCM) For 8HP76/51 Transmission -- Defender/L663 >> Diagnostic Trouble Code Index - DTC: Transmission Control Module (TCM) For 8HP76/51 Transmission (G2413630) >> Description And Operation >> Transmission Control Module (TCM) - 8HP76/51 Transmission >> DTC U0028-88: Vehicle Communication Bus A - Bus off >> Possible Causes