U0101: Lost Communication with TCM
HighNetwork/CommunicationCommunication Bus
What does U0101 mean?
U0101 is a diagnostic trouble code indicating "Lost Communication with TCM". The vehicle's main computer has lost its ability to communicate with a specific module over the data bus. This could be caused by a wiring fault, a blown fuse, or a failed control module.
Symptoms you may notice
- Check engine light (MIL) illuminated on dashboard
- Noticeable change in engine performance
- Unusual sounds or vibrations
- Possible issues with communication bus operation
- Vehicle may enter reduced power mode (limp mode)
Estimated repair cost
Typical range in Australia (parts + labour)
$200 – $1500 AUD
Common causes
- Failed control module
- CAN bus wiring fault or short
- Blown fuse to the affected module
- Water intrusion in a connector or module
- Battery voltage too low
What should you do?
This code sits in a powertrain control module. The engine or transmission can drop into limp mode or cut out, which is its own hazard in traffic or on a motorway. Get it diagnosed before your next trip rather than waiting for the next service.
Get a diagnosis for YOUR car
Code U0101 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.