1. Home
  2. /
  3. Complete List of OBD2...
  4. /
  5. U0101 Code – What...

U0101 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


U0101 is an OBD-II Code that refers to Lost Communication with Transmission Control Module (TCM)


A U0101 code indicates that the engine control module (TCM) and other control modules on the vehicle are not communicating with one another. The most frequent way to connect devices is via the Controller Area Network (CAN) bus. If this (CAN) bus is disrupted, control modules will be unable to communicate information. Furthermore, if your scan tool can’t retrieve information from the car, one of the circuits may be malfunctioning.


Common causes for this code include:

  • Ineffective TCM
  • Connectors that have been damaged
  • Wiring that has been damaged
  • Ground connection damage


The symptoms of a U0101 code are:

  • There will be no shift in gear.
  • The vehicle’s transmission won’t budger out of forward gear.
  • Limp mode


To diagnose a U0101 DTC code, a technician would:

  1. Look up the manufacturer’s TSB database to see whether a known reason or remedy exists.
  2. If none are discovered, the CAN bus system’s wiring and connections must be checked for signs of wear and corrosion.
  3. Any grounds, fuses or relays that are connected to the TCM must also be investigated.
  4. If no issues are discovered at this stage, the TCM will have to be inspected.

Common mistakes

The following are common mistakes when diagnosing the trouble code U0101:

Mistaking engine noise as a sign of an issue with the TCM

Not checking whether there’s corrosion on the battery terminals

Not investigating whether any fuses are blown or relays are faulty

Ignoring signs of wear on vehicle wiring

How serious is this?

A U0101 code is serious, but it doesn’t mean that you have to get rid of the vehicle. The TCM isn’t a crucial system in your vehicle. It controls one part of the transmission—the lockup torque converter clutch solenoid circuit. Also, a U0101 can be a result of a minor issue with your transmission system or even an overheating issue.

What repairs can fix the code?

The following are solutions that may fix this problem:

  1. Replacing the TCM
  2. Replacing wiring that has been damaged or worn out
  3. Resetting the PCM or TCM by removing power from the battery for 10 minutes.
  4. Checking whether there’s corrosion on your battery terminals and where connections are made to clean them up.

The U0101 code is a little more complex to diagnose since there’s no unique solution that solves it. Most individuals just leave the repair up to their auto technicians. You might attempt to fix it yourself, but you’ll need assistance from online instructions or repair manuals.

Related codes

A U0101 is related to and may be accompanied by the following codes:

  • U0100 – Loss of K Line
  • U0102 – Transmission Output Shaft Speed (POS) Sensor Circuit High Input 
  • U0103 – Transmission Output Shaft Speed (POS) Sensor Circuit Intermittent 
  • U0104 – Transmission Fluid Temperature (TFT) Sensor Circuit Range/Performance 
  • U0106 – Open in Torque Converter Clutch Solenoid Valve Circuit 
  • U0201 – Missing Message From ECM/PCM to TCM or U0100 & U0102 Codes Present

How much does it cost to fix the U0101 code?

The repair cost of a U0101 code depends on the severity of the issue causing it. If you bought your car recently, a U0101 code can be a minor issue that doesn’t require a major fix. You can have it fixed within an hour or two. Most times, you’ll just need to replace the TCM.

If the problem is more severe, you might need to wait a little bit longer because the part will need to be ordered first. The cost of replacing your TCM can range from $700–$1,500. Typically, you won’t be paying more than $1,000 for this type of repair. If you don’t want to spend that much money on repairs all at once, then simply look for someone who specializes in auto repairs and see if they can fix it for less or let you make payments over time instead of shelling out all the cash immediately.


In conclusion, the U0101 code is a DTC (diagnostic trouble code) that’s common in most vehicles. It reveals an issue with the TCM, which controls your vehicle’s lockup torque converter clutch solenoid circuit. A U0101 is serious, but it doesn’t mean you should get rid of your car. This problem is often resolved with professional, certified assistance.

You can try to fix it yourself, but you’ll need assistance from online instructions or repair manuals. The cost of repairing your car varies depending on the level of repair needed.

U0101 Code – What Does It Mean & How To Fix It