OBD codes / U0101
U0101
SeriousLost Communication With Transmission Control Module (TCM)
Address promptly — can worsen or affect drivability.
Likely causes
- data bus wiring fault
- failing TCM
- power/ground issue
Common fixes
- inspect bus wiring to the TCM
- check TCM power and ground
Seeing U0101 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose U0101 for my vehicleGeneric OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.