Code
U0101
Network
Lost communication with transmission control module
Modules cannot communicate with the transmission controller over the network.
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Most likely causes
- TCM power or ground fault
- CAN bus wiring fault
- Failed TCM
Symptoms you may notice
- Transmission warning
- Limp mode
Checks to run
- Check TCM power and grounds
- Test CAN wiring
- Scan TCM
Tools you may need
Multimeter
OBD-II scanner
Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.