How To Fix U0100 Code? [4 Simple Steps]

These days, computer forms a major part of the working of a vehicle, that is linked with a complex network of communication system some sorts of diagnostic problem codes are available (DTCs). The scanner for the codes is shown with the Pxxx codes (engine and transmission). The coding instructions can be simply accessed online.

Codes associated with body computing are Bxxx codes, while codes connected with the chassis are Cxxx codes. The many componenst in your vehicle cannot connect with each other without this communications path. U0100 is a general error code indicating a network communication problem. In this detailed guide, learn how to fix u0100 code and the reasons for it.

What U0100 Error Stands For?

Knowing about the code helps a lot in how to fix u0100 code. The DTC U0100 is the Lost ECM Communication. This is triggered when your PCM and a particular module are lost in communication. If so, the vehicle may be shut down and not restart unless there is a resolution to the problem causing the code. The whole system is connected to other car modules by data system.

Many cars use a protocol known as a controller area network to communicate between modules (CAN). This means that the bus is called the CAN bus. A CAN bus system is provided for your vehicle. This can bus communication link is the key so that different modules of the car can talk with each other and perform their functions.

What Causes U0100 DTC Error?

This is not an ordinary issue. I have learned that the ECM, PCM, or transmission control module is the most likely failure. In a vehicle there are two or more CAN bus stops. They can be located under the carpet, behind panels, under the driver’s seat, behind the dash, or between the A/C box and center console.

They handle all modules with communications. Such a code is caused by the bad terminal bent or damaged out in one connector, or by loose corrosion on the computer. The wrong polarity while jump-starting a car, accidentally can toast your car electrical. It may not be compatible to install performance improvement chips or gadgets that may miscommunicate with ECM.

How To Fix U0100 Code?

The code U0100 stands for lost signals between modules. This shows that there are problems in the signals with another module in the electronic control module (ECM), also known as the powertrain control module (PCM). learn how to fix this issue in the following steps-

1. First Clear All Codes

The basic step in the steps for how to fix u0100 code. The code U0100 error is not that common. The consequence can possibly be a dead battery. Clear the code to start, and observe whether it will happen again. When the code comes back, a visual check will be carried out. U0100 to U0300 codes are associated with failed modular communication. The network communication codes are also related to other U codes.

2. Check The Wiring

The electric cable comprises stranded, cross-section, copper wires with particular plastic isolation. Cabling is gathered and placed in particular troughs on the body. Electric tape, clamps, and clips are used to attach the electrical cables. You should look out for the corroded terminals first during wiring test.

The color of car cabling for convenience and difference varies depending on whatever device is used. Color coding is done to ease troubleshooting and make maintenance easier for vehicles. The maker applies the marking. Use a handy multimeter to check the various values of the wiring.


3. Verify The ECM/PCM

We have a side of the battery with power, a device we control, or a sensor from which we read a ground and a value. The earth fits the circuit back to the battery.

When you are connected to several ground wires of the same 2 points, the current is shared across the two alternating ground channels. The ECU shares some starting engine current in other words. In other words, check for the ECU grounds as it can be the whole problem.

4. Car Battery Could Be Bad

The car battery plays a very important role in modern cars. The ECU/PCM relies heavily on them, in order to function properly. The CAN bus system particularly requires a voltage within certain limits, so that it can communicate properly.

If your car happens to have a bad battery, then the CAN bus system will not be able to operate properly and chances are high that you will get this error in this case. So in this case, getting a new battery or getting the older battery recharged, if it is still good, are the only options to fix this error.

Common Symptoms Of U0100 Error


A control engine light is the most prevalent symptom of this code. However, depending on the vehicle, you may not have warning lights or you may not have warning lights. The only way, in that case, is to get the codes from a scanner.

The symptoms of the U0100 code range from no symptoms at all to the risk of your vehicle not starting or even starting. Once this is done, your car should be tested for the correct diagnosis right away.

Cost Of Fixing U0100 DTC Code

It takes 1.0 hours to troubleshoot the U0100 code. The work rates for the automotive repair and diagnoses do differ as per the state, car manufacture and model, and even your motor type. The majority of car repair firms charge $75 to $150 per hour. If any major module is to be replaced, then be ready to shell out upwards of 1000$.


The error code U0100 can leave you standard if not taken care of in time. By learning how to fix u0100 code and the associated symptoms, you can avoid a nightmare of repairs. Do not ignore this problem and get it repaired as soon as possible.

Also, avoid installing any 3rd party accessory in modern cars if it is not specifically designed for your car. Comment down below for any further questions.

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