How to Fix the U0101 Code on Duramax (The Expert Approach)

Today’s vehicles are equipped with modern computer technology, which simplifies the activities of different systems in a car. There is an entire communication system that is controlled by other computer modules.

These modules allow the functions of this network to exchange information with each other. The entire network system will be affected if one or more modules can’t communicate with one another.

The diagnostic trouble code u0101 on DURAMAX means that the TCM (Transmission Control Module) has lost communication with one or more modules. When this communication system is lost, the entire computer system fails to regulate the engine properly. In most cases, replacement of the TCM is required. Let’s figure out other information regarding this case.

Duramax U0101 Code

What Does the U0101 Code Mean on Duramax?

The generic communication system trouble code u0101 on a Duramax indicates lost communication between the TCM and other control modules.

The code u0101 indicates that the transfer control module (TCM) and the engine control module (ECM) or the powertrain control module (PCM) are not exchanging information with one another.

A Controller Area Network (CAN) bus connects these control modules. Once this CAN bus is disrupted, the modules cannot receive or transmit messages. As a result, scan tools cannot obtain information from the car.

It leads the code u0101 to be set on Duramax to determine that the entire communication system has been lost. Here’s a breakdown of the trouble code u0101 on DURAMAX:

  • U = Network and vehicle integration. The onboard computer system managed them.
  • 0 = Standardized code. Known as generic or sometimes known as global code.
  • 1 = Defines fuel and air metering issues.
  • 01 = Individual Fault Index. In this case, it stands for Lost Communication.

How Serious Is the U0101 Code on Duramax?

Detecting the code U0101 on Duseveres is serious enough when the problem is with the TCM. This module controls the lockup torque converter clutch solenoid circuit of your vehicle. Problems with this circuit may lead your Duramax to get into limp mode.

This code can also be set due to minor issues like wiring problems or overheating issues. These problems don’t make your vehicle unusual, but they need quick fixing before they worsen.

What Are the Symptoms of the U0101 Code on Duramax?

The malfunction indicator lamp (MIL) will turn on when this code is set on Duramax. Other common symptoms include:

  • The vehicle may go into an emergency or limp mode.
  • Gear will not be changed (mainly 2nd or 3rd)
  • The transmission won’t switch from a forward gear
  • Scan tools become unable to communicate with TCM

What Causes a U0101 Code on Duramax?

The error code u0101 can appear on your Duramax for various reasons. The ineffective connection between the transmission modules and the CAN bus is pretty much the most common reason among them. Other common causes include:

  • Defective TCM
  • Damaged wiring and connectors
  • Faulty CAN bus circuit
  • Problems in the ground connection
  • Dead battery

How to Fix the U0101 Code on Duramax?

Since the root cause of the problem is a bit tricky, fixing the U0101 code on Duramax can be troublesome. So, it’s good to leave the job to a professional mechanic.

But you can also try it on yourself by following the possible solutions listed below.

Step-1: Examine all fuses and grounds

Examine all of the fuses to ensure that they are functioning correctly and that they are supplying power to the TCM module. If they work, examine all ground connections for the TCM module.

Make sure that all the connectors are clean and tight. If they aren’t, clean them using a baking soda solution.

After cleaning, clear the code and see if the code returns or not. If it comes back, try the next step.

Step-2: Locate the CAN bus communication connectors.

 Place the CAN bus communication connectors, especially the TCM module. Before unplugging the connector at the TCM, detach the negative battery cable. Now look for any damaged wiring or burnt plastic. 

Visually inspect the terminals inside the connectors. If you notice any burned or melted spots, clean the terminals using an electrical contact cleaner. Now let them dry and utilize some silicon grease where the terminals connect.

Remove the code again and check whether it comes back. If the communication is still impossible, attempt the next step.

Step -3: Check the voltage

Use a digital volt-ohmmeter to check some voltages before reconnecting the connectors to TCM. Connect the detached negative battery back to the TCM module.

Now combine the red voltmeter lead to each B+ and the black voltmeter lead to the ground. Then determine the reading of the battery voltage and diagnose.

Similarly, check the battery voltages at each connection. Verify that the voltage is within the required range. If not, jump to the next step.

Step-4: Check the two communication circuits

CAN C+ and CAN C- are the two communication circuits. Connect the black lead of the voltmeter to CAN C+. Now verify if there are 2.6 volts and fluctuate slightly.

Afterward, connect the red lead of your voltmeter to CAN C-. Determine if there are 2.4 volts and fluctuate slightly. If the error code still appears, the last chance to get out of it is to change the TCM module.

Step-3: Replace TCM

When you denote the TCM is damaged, it needs to be replaced. The required steps are discussed below:

Step One: Collect a new TCM

Buy the correct TCM that is suitable according to the year, make and model of your DURAMAX.

Step Two: Locate the TCM

Open the hood and figure out the TCM.

Step Three: Dispel the damaged TCM.

Remove the old TCM by unscrewing the screws or the bolts that allow the TCM to keep it in place.

Step Four: Install the new one.

Install the new TCM by doing things opposite to what you did to eliminate the previous one. Use the same screws and bolts and finally attach the wiring to the data port. 

How Much Does it Cost to Fix Duramax U0101 Code?

The cost of fixing the code U0101 on Duramax relies on the problem that must be set to resolve the code. If the code has a minor issue, it won’t require a major fix. In this case, it may cost around one or two hours of labor.

In contrast, if the problem with the code is a major one, it may take a little more time to diagnose and finally fix the problem.

But in most cases, the TCM requires a quick replacement. The cost of replacing TCM may range from $700 to $1500.

Can You Drive Your Duramax With Code U0101?

Driving your Duramax with this code is not safe at all. Your Duramax can suddenly get stuck into the limp mode, which will restrict the transmission into a single gear. It can cause fatal accidents.

So, whenever you get the code u0101 on your Duramax, fix the possible reasons and resolve the code. And then attempt to drive your vehicle.


You must diagnose and resolve the issues associated with the code U0101 before the situation worsens. Though this trouble code is responsible for creating many serious conditions on your Duramax, there are several ways to resolve the code from your vehicle.

You can go through any of them. You can also try to fix the code u0101 by following our instructions discussed in this article. However, it’s preferable to leave the job to a professional technician and have the code resolved as soon as possible.

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