Low battery voltage. A blown fuse or bad ground to the TCM. Damaged or corroded wiring or connectors (TCMs on some vehicles sit inside or on the transmission). A failing TCM.

Trouble codes › U0101

U0101 Lost Communication With TCM

Q: What does U0101 mean?

U0101 means other modules have lost communication with the transmission computer, which can put the transmission in limp mode. Another module on the network stopped hearing from the transmission control module (TCM).

Network

U0101 means other modules have lost communication with the transmission computer, which can put the transmission in limp mode.

Another module on the network stopped hearing from the transmission control module (TCM).

Can I keep driving? Yes, but get it fixed soon.

The transmission may be stuck in one gear (limp mode). Drive gently and get it checked soon.

Common causes

Low battery voltage
A blown fuse or bad ground to the TCM
Damaged or corroded wiring or connectors (TCMs on some vehicles sit inside or on the transmission)
A failing TCM

Symptoms

Limp mode
Gear indicator blank or flashing
Several warning lights

What to check first

Check the battery and connections.
Check the TCM's fuses, power and grounds.
Inspect connectors at the TCM for fluid or corrosion.
Check for service bulletins on your vehicle's TCM.

What does U0101 mean on your vehicle?

The likely cause depends on your engine. iRepair researches your exact year, make, model and engine (service bulletins, recalls and owner reports) and tells you what to check first. Your first 3 questions are free.

Ask iRepair about U0101

No scanner? Most auto parts stores read check-engine codes for free.

Related codes

General guidance for U0101 on most vehicles. Some makers use the same code a little differently; confirm in the service information for your vehicle, put safety first, and see a professional when in doubt.