Lost Communication with Transmission Control Module
Your vehicle’s computer has lost contact with the transmission control module. This can cause shifting problems, warning lights, limp mode, or no-start issues on some vehicles. The problem is often caused by wiring, power, ground, fuse, or module failure.
You may be able to drive short distances, but shifting can be abnormal and the vehicle may enter limp mode. If the transmission is stuck in one gear, slips, or the warning lights are severe, do not continue driving.
U0101 means the engine control module or another networked module has detected a loss of communication with the transmission control module (TCM). This is a network or power delivery fault, not necessarily a direct transmission mechanical failure. The root cause is commonly a blown fuse, bad power or ground, damaged CAN wiring, connector corrosion, or a failed TCM.
Usually no. U0101 is a communication fault, so the first checks should be power, ground, wiring, connectors, and the TCM itself.
No. The code will usually return if the communication problem is still present.
Yes. Low system voltage can cause the TCM to drop offline and set this code.
Not usually. This code points to an electrical or module communication problem, not a mechanical transmission failure.