U0101 on Mercedes-Benz
Lost Communication with TCM
U0101 on Mercedes-Benz vehicles indicates lost communication with tcm. Au7o has documented this code across 1 Mercedes-Benz model — most commonly on AMG GT. This is a network communication code meaning a control module on the vehicle's data bus has lost communication with the Transmission Control Module (TCM). Modern vehicles use a shared data network (commonly CAN bus) so modules can exchange information; when the TCM stops responding or its messages disappear, other modules set this code. Because the transmission relies on this communication to shift properly, the vehicle may go into 'limp' mode, hold one gear, or refuse to shift normally. It generally indicates a wiring, power, ground, or connector problem on the network — or a failed TCM itself — rather than an internal mechanical transmission fault.
Common Causes of U0101
- •Damaged, corroded, or loose TCM wiring or connectors
- •Open or short in the CAN bus data wiring
- •Blown fuse or lost power/ground to the TCM
- •Corrosion or water intrusion at the TCM connector
- •Faulty Transmission Control Module
- •Another faulty module dragging down the data bus
- •Poor ground connection in the network
U0101 on Mercedes-Benz by Model
Mercedes-Benz AMG GT(1 issue)
- Misrouted Transmission Wiring Harness Connector Corrodes and Short-Circuits (Fire Risk, Recall Repeated After Failed First Remedy)2019-2025
On the X290 four-door AMG GT (GT 43 / GT 53), the transmission wiring harness can be routed incorrectly so that the electrical connector sits where it is exposed to water and road spray. The connector corrodes, and the corroded contacts can short-circuit — which Mercedes-Benz itself describes as increasing the risk of fire, and which can also strand the car with transmission fault messages. NHTSA campaign 22V533000 covered 2019-2022 GT 53 and 2021-2022 GT 43. That remedy did not hold: campaign 24V445000 was opened afterward for 2019-2025 GT 53 and 2021-2024 GT 43 because the harness connection 'might not have been correctly wired during a prior recall repair or during production' — meaning cars that already had the first recall performed can still be defective. This is a four-door X290 issue tied to the 9G-TRONIC installation and does not transfer to the C190 two-door's rear transaxle DCT.
Looking for U0101 on a different make?
View U0101 across all makes →Frequently Asked Questions
What does U0101 mean on Mercedes-Benz?▼
U0101 stands for "Lost Communication with TCM." This is a network communication code meaning a control module on the vehicle's data bus has lost communication with the Transmission Control Module (TCM). Modern vehicles use a shared data network (commonly CAN bus) so modules can exchange information; when the TCM stops responding or its messages disappear, other modules set this code. Because the transmission relies on this communication to shift properly, the vehicle may go into 'limp' mode, hold one gear, or refuse to shift normally. It generally indicates a wiring, power, ground, or connector problem on the network — or a failed TCM itself — rather than an internal mechanical transmission fault. On Mercedes-Benz specifically, this code is documented across 1 model.
What causes U0101 on Mercedes-Benz vehicles?▼
Common causes on Mercedes-Benz: Damaged, corroded, or loose TCM wiring or connectors, Open or short in the CAN bus data wiring, Blown fuse or lost power/ground to the TCM, Corrosion or water intrusion at the TCM connector, Faulty Transmission Control Module. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix U0101 on a Mercedes-Benz?▼
Repair costs vary widely depending on the root cause and specific Mercedes-Benz model.
Which Mercedes-Benz models have U0101 documented?▼
Au7o has documented U0101 on 1 Mercedes-Benz model: AMG GT.