How To Fix U0100 Code Of Your Car If You Face?

The various computer modules in charge of the many systems aboard a modern vehicle are connected by a data network. On vehicles built after 2008 and some older models, the modules use a protocol called CAN (controller area network) to communicate. Any issue that prevents one or more modules from talking to their peers through this network may trigger the U0100 code.

The U0100 code is a generic network communication code. The PCM is the computer responsible for the engine’s management. The PCM communicates over a bus known as the controller area network (CAN).

The CAN allows the PCM and other modules to communicate with one another. If the U0100 code appears, it means signals are getting lost between the PCM and one or more of the other modules onboard the vehicle.

Below there are the following steps to know how to fix U0100 code.

What Does The U0100 Code Mean?

Diagnostic Trouble Code(DTC) U0100 is a Manufacturer-Specific Network Communication Code. This means that it does not have a standardized definition from the society of automotive engineers. The code usually indicates that one module did not receive the message it was expecting to get from another module.

Dedicated control modules control the brakes, engine, transmission, and other vital systems in your car. These computers communicate over a data bus. Thanks to this extensive level of interconnect between modules, it becomes possible to get the most performance out of a vehicular system by adjusting the activity of a related system.

U0100 is a common issue among the following makes Nissan, Infiniti, Chevrolet, and Cadillac.

What Are The Possible Causes Of The U0100 Code?

Several issues may prompt this Diagnostic Trouble Code to appear in the control module’s log. These causes include:

  • An issue with the data bus is known as the controller area network(CAN).
  • Circuit issues, such as damaged wiring or poor connections.
  • A module that has failed or has outdated software.

What Are The Common Symptoms of Code U0100?

Given the number of computer modules that communicate with each other, the warning signs of a U0100 code may appear as a seemingly unrelated problem until you plug in your scanner. Nonetheless, here are the symptoms you may experience:

  • Check Engine Light.
  • Another Diagnostic Trouble Code that warns about a malfunctioning computer module.
  • Various issues in the vehicular system are controlled by the affected module.

Now, apply that loss of control to something crucial, like the engine, and you’ll understand the critical nature of the U0100 code.

How Serious The Problem Is?

The U0100 code is monitored when the vehicle’s ignition is on. The battery voltage needs to be at a certain level and other modules need to be correctly configured. The code indicates a serious situation.

Vehicles with the U0100 code can experience sudden shutdowns while running. They may also not restart. Without communication between modules, it will be difficult trying to drive the vehicle.

How To Fix U0100 Code?

Now that we know what could be causing our error, let’s go over how to fix U0100 code. We’ll work through things methodically, to ensure that we’ve covered all of our bases before we decide that it’s actually time to replace our PCM. After all, we don’t want to do that unless it’s necessary.

1. Check Your Battery

This may sound obvious, but first, check your voltage before you look at anything else. Your PCM requires a full charge to work properly. If your battery is pushing anything less than 12 volts, try replacing it with a new one before you move on to anything more complex.

2. Check For ECM And BCM Trouble Codes

Before you start doing anything more complex, examine and additional error codes you might have encountered with the code reader. Check your car for any ECM or BCM trouble codes. This can mean there are deeper, underlying issues with your engine, so we want to rule those possibilities out first.

In case there is an issue with your TIPM or BCM, try to fix those parts. They are on the same harness as the PCM and can cause faults if they fail. In case the problem is with your ECM, diagnose that carefully before proceeding.

3. Check The Wiring Harness

The next thing to do is to check your PCM wiring harness for faults. This is a pain, but it’s a necessary step to find a remedy. If you find any arcing, exposed wires, or damaged insulation, don’t mess around. Replace the wiring harness immediately and see if it solves your problem.

4. Check The CAN Bus Connection

The next thing to do is check your Bus known as controller area network (CAN). Use your code reader to see if any codes indicate trouble with the controller area network (CAN). Then, use a multimeter to check both the (+) and (-) circuits on your controller area network (CAN) for shorts. If everything reads normal, it’s time to check the PCM.

5. Check The PCM

If everything else is in good working order, you’ll need to check your PCM itself for trouble. Use your multimeter again, and check the (+) and (-) connections on your PCM. If there’s a short there, it may be possible for a mechanic to simply replace your PCM’s power supply. If power is flowing normally, the issue is with your PCM itself.

These are the steps of how to fix U0100 code. Follow that so that you can repair otherwise take the car to the proper mechanics.

What Is The Cost To Diagnose The U0100 Code?

The cost to diagnose the U0100 code is 1.0 hours of labor. The auto repair’s diagnosis time and labor rates vary by location, vehicle’s make and model, and even your engine type. Most auto repair shops charge between 75$ and 150$ per hour.


The U0100 code indicates a serious issue. If the code is not cleared, the vehicle will have issues with starting up and can shut down.  Codes U0100 to U0300 are related to lost communication with modules. Other “U” codes are related to network communication codes.

The definition of code U0100 will vary depending on the auto manufacturer. Thus, a U0100 Nissan case may differ from a U0100 Chevy scenario. Refer to the appropriate repair manual or repair database for the exact definition.

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