What is the meaning of this U0101 code, and how to solve this?


The most frequent code seen in the OBD 2 scanner is U0101. This problem is connected to the transmission control module or TCM connection.

What is the meaning of code U0101?

Trouble code U0101=Lost Communication with TCM

At the top of the article, the code U0101 is related to the transmission module. That means when your car can’t control the transmission module and the OBD2 scanner gives the message “U0101”. As a result, this code indicated that the engine and other control modules on your vehicle were under your control. When this is not communicated with another module, then this problem happens. The Controller Area Network (CAN) is primarily used to link devices. If this CAN bus cannot find the problem, then the control modules are unable to pass the information. In that case, if the scan tool of your vehicle can’t find the situation in the meantime, it can’t retrace the communication report, and you will also notice any faulty circuits.

What are the possible causes of this U0101 code?

Is there any reason to show the code U0101 on your car screen? Yes. There are some common reasons for this problem. Like:what causes a u0101 code

  • Defective TCM,
  • Poor or damaged connectors,
  • Faulty wiring,
  • Damaged ground connection.

What is the symptom of this U0101 code?

There are some common symptoms; you also notice some signs in this code. If you see the symptom early, you can quickly solve the problem. Like:

  • Shift gear is absent,
  • Unable to change the transmission gear,
  • Limp mode.

How to diagnose the code of U0101?

There are some steps to diagnosing the code of U0101. And every technician follows this step carefully. How to diagnose the code of U0101

  1. First, search the manufacturer’s TSB information site. Many times you can find the same problem solution there. This is the easiest way to find fault with your transmission control module.
  2. After the scan, if you don’t find the fault, check every wiring and connection of the CAN bus. Sometimes the poor relation of this bus is also the reason for this problem.
  3.  The ground fuses also need to be checked because this is also related to the TCM connection.
  4. Until now, if you cannot find the problem with the transmission module, it needs to check TCM properly. 

So if you follow all these steps, I think you can easily find the reason for this code.

Some common mistakes you make when you diagnose the U0101:

People often make mistakes to find the exact problem for this code in the OBD2 scanner. Like:

  • The noise of the engine is a sign of a problem in TCM,
  • If there is corrosion in battery terminals, you don’t check this portion.
  • Miss the investigation where the fuses are malfunction,
  • Don’t notice the lose connection wire of the vehicle.

How to fix this U0101 code?

We talk about all possibilities about why this problem happens. So you also need to know how to solve this problem. This is a straightforward process. Like:

  • Repair or replace the damaged TCM,
  • If there is poor or damaged wiring, replace that.
  • Removing power from TCM or PCM for 10 minutes to reset the whole process,
  • Check if there is corrosion in your car battery or not; if it happens, then clean them up.

 This U0101 code looks like a simple problem, but it has a complex diagnosis process because there is no fixed solution to solve this problem; most of the time, you need to rely on professionals to solve the problem. If you want to DIY it, try to follow the suggestion of a professional or get help from Google or YouTube.

Why is it mandatory to solve this U0101 code?

U0101 code related to the communication of the transmission control module. So this is a significant problem in your car. But you can solve it quickly. You don’t need to change your car to solve this problem. The TCM system is a very important part of your car. It controls a significant transmission part that locks the torque converter to clutch the solenoid circuit. So this U0101 is a minor issue for your vehicle, like overheating the engine. But try to solve the problem as soon as possible.

For a brand new car, this U0101 code is a minor issue. So you don’t need to do a significant fixing. And this fixing needs not more than two hours. For a new car, replace the TCM to fix the problem.

How much does it cost to fix it?

If you got a significant problem, you need to wait for some extra time to solve the problem. And ill suggest you go with the help of a professional. The replacement cost of TCM is around 700$ to 1500 $. So you don’t need more than 1000$ to solve the problem with your car.


For some time, the U0101 code has not been a significant issue. But try to solve this problem before you start to test drive it. And after decoding, the problem restarts the program to check whether the problem is fixed. If your OBD 2 scanner doesn’t show any messages, you have solved the problem. And if you see the issue again, then get help from a professional to fix the car.

Kevin Nicholas is an automotive technician who is a genius at software and hardware-related issues. He manually tested more than a hundred OBD scanners and gave his honest opinion on whether the device was worth the money or not. His in-depth OBD review articles help people choose the right product, whether it is a European, American, or Asian vehicle. He completed his Automotive Specialized Training Course at Universal Technical Institute and has more than 15 years of experience in the field.

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