Code U0101 Lost Communication With TCM – [Solved]

In some vehicles like Ford, Nissan, Mazda, and many more, the trouble code U0101 appears after a scan by the OBD-2 scanner. This code means, that all the control modules of that vehicle including the Transmission Control Module (TCM) lost communication.

But these lines are insufficient to provide you with a clear idea about code U0101 lost communication with TCM. Details and on-pointed discussion is necessary for better understanding. Here we are going to make things clear about DTC U0101. Let’s explore.

Does Code U0101 Mean Lost Communication With TCM?

Yes, the code, U0101 means other CM lost communication with TCM. There is a central point of all control modules in the engine. That is called the Controller Area Network bus or CAN bus. The main task of that circuit is to maintain communication between control modules.

But when CAN Bus fails to work, the communication process break then the trouble code U0101 appears on our scanner. So, we can say that code U0101 means lost communication with TCM.

Symptoms Of Diagnostic Trouble Code U0101

There are many possible symptoms of a diagnostic trouble code U0101, and it is important to have your vehicle inspected by a professional if you experience any of these. 

The most common symptom will happen on TCM so transmission shifting will be hard. Some more symptoms are there that are also important to know. Let’s see these symptoms:

  • Check Engine Light On
  • Gear Shifting Problem
  • Vehicle Will Shift to 2nd or 3rd gear
  • Instrument cluster PRNDL display
  • Diagnostic Scan Tool Will Not Be 

If you notice any of these issues, be sure to bring your car in for an inspection as soon as possible so that the problem can be diagnosed and corrected. Also, you need to know the causes of happening this problem to avoid further problems.

Why This Code May Appear?

You must know the reason for this trouble code because we already told you that. But exactly the CAN bus is the main place where the trouble may occur. If the CAN bus fails to maintain communication between the CMs, this code may appear. So, you need to work on that area if you are planning to fix this code.

Some other possible reasons are:

  • Power shortage in CAN bus
  • Connection problem
  • CAN bus circuit issue
  • Faulty Control Module

How To Fix Code U0101 Lost Communication With TCM?

Before you start the solution process, you need to know the reason behind this code and lost communication with TCM. Because there are so many possible causes of this code in your vehicle. And for the same reason, it is complex too.

First of all, you need to check the battery connection and battery itself of TCM and the network bus. If there is any problem, you must ensure proper connection. If the battery itself is dead, try to replace it.

The second possible cause is complex to fix because it is completely a part of the circuit. Sometimes you may create more problems rather than fix it. So, if you lack confidence then avoid the process. You need to have the technical and mechanical knowledge to fix them. But we avoid suggesting to fix at home.

How Much Does It Cost To Fix Code U0101?

As the causes of this diagnostic code are many, the fixing method is also not the same. For these different fixing methods, the cost is also not fixed and it is also almost impossible to give you an exact idea about cost.

But you may require $100 to $1000 to fix this code. In this cost, the mechanic cost is included. The lowest cost will be if the connection only has an issue. But any problem with the battery and TCM itself will make your wallet empty.


The Code U0101 Lost Communication With TCM will become a serious issue for your vehicle’s transmission system if you don’t take it seriously. So, understanding this and solving is very essential.

If you’re having trouble understanding or deciphering your car’s diagnostic Trouble Code U0101, after reading this discussion, take help from experts. Thanks for reading from us. Some more discussions are there about the trouble codes on our site. You may read them too to enrich your knowledge.

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