BMW 801C20 Fault Code, cause, how to fix?

BMW 801C20 Fault Code is error that the central memory is full and stored in the control module ZGM (central gateway module) but there is no error of the controller.In this article the experts come from Eurocartool will help you understand the cause of the error as well as how to fix it effectively. Follow the article below.

What is the BMW 801C20 Fault Code?

  • Technical description of error code: 801C20 – ZGM_Central fault memory full-no contol unit fault – Pemanent
  • Severity: Moderate
  • Repair request: The error code will cause the vehicle’s electrical system to flicker, low voltage, unable to unlock the car or use utilities such as listening to music, lighting system
  • Error diagnosis: The central fault memory in the ZGM control module may be full and store error code 801C20. This does not necessarily indicate an electrical problem in the vehicle, as it can be the result of many other problems that can also be stored in the module. Usually, low voltage in the vehicle is the main cause of this problem. To diagnose this, use a multimeter to check the voltage of the battery. The ignition system must show at least 12 volts and the voltage should be 14.30 or higher after starting the engine at idling speed.


Why does the BMW 801C20 error appear?

The cause of the BMW ZGM fault:central fault memory full-no control unit fault error can be caused by an electrical system problem such as:

  • After replacing the battery: When the vehicle battery is replaced or exhausted, this error code can also be caused. You just need to encrypt the new pin to solve the problem.
  • Voltage drop: During the battery replacement process, it may cause the central module to lose programming, preventing your vehicle from reading the new battery.
  • Errors on any other control module can also be logged in the ZGM box
  • Some other causes such as: The wiring of the control module is broken, the fuse of the control module is broken, The car audio system doesn’t work,…

If all electrical systems in the vehicle, such as the central locking and the music system, are working properly, this error code can be ignored as it would normally be stored in the control module.

Expression when the car encounters error BMW 801C20

This BMW 801C20 code often appears with electrical problems in the vehicle, preventing you from using amenities such as

  • The music system could fail to operate.
  • The central locking system is experiencing issues.
  • The air conditioning system might cease to function.
  • There could be other problems with the vehicle’s comfort system.
  • Other control modules could potentially malfunction.


Instructions on how to fix the error BMW 801C20

In this section, experts will provide ways to fix or repair the root of the BMW 802C20 error case by case.

Low battery voltage

The main cause of this error code stored in the control module is low battery voltage. To solve this problem, check the voltage of the battery and recharge it if the voltage is below 12V. It is also important to assess the condition of the battery, as the battery may need to be replaced if it weakens over time. Insufficient voltage due to low battery power may cause the control module to fail to function properly.

To remedy this, charge the battery to full capacity or replace it so that the control module can receive the required amount of voltage. If the voltage current meets the requirements of the control module, this error code can be prevented from being stored. It is sometimes necessary to encrypt a battery after replacing the old battery with a new one.

Fuse is broken

To fix a blown fuse, find the fuse box on the left side behind the glove box. Find the ACC fuse and check if it’s blown. If so, replace it immediately. This fuse is responsible for supplying power to most control modules when the ignition is turned on. If it explodes, it cuts off the ignition power to all control modules and the error can be saved in the control module.

Power line is broken

The connectors of all control modules contain a variety of wires, including those used for power supply, grounding, ignition voltage, signal wires, CAN wires, and more. All these wires are necessary for the normal operation of the control module. If any of these wires is damaged or broken, the control module may stop working properly. Therefore, this could be the reason why the error code is stored in the control module.

The car’s comfort system is faulty

If there is an electrical problem in the vehicle’s comfort system, such as the central locking not working, the power windows not working, the headlights not turning on or the music system not working, the error code will be saved in the control module. However, this does not necessarily mean that the problem lies with a faulty ZGM control module.

To identify the specific control module that is malfunctioning, check the error code. For example, if the central locking system does not work, check the CAS control module for the relevant error code. Solve the error code stored in the control module first to solve the problem.

Control module is faulty

If a control module in the vehicle malfunctions, it can disrupt communication between the various comfort systems operated by multiple control modules. These modules are connected to each other via CAN cables and they work together to give the driver a comfortable driving experience.

However, if a module fails due to a blown fuse, damaged wiring or other reasons, the module will stop communicating with other modules. This may cause problems with the ZGM control module and as a result 801c20 bmw code may be stored in the module.

How to fix BMW 801C20 Fault Code?

In this case, it is recommended that you use BMW soft-touch and professional equipment to diagnose, clear the fault memory and restore the functionality of the vehicle’s electrical system.
To fix BMW error code BMW 801C20 you will need the following hardware and software:

  • The BMW diagnostic tool is capable of communicating with a ZGM module, such as the BMW ICOM Next, Autel MaxiSYS Elite or Launch X431 V+.
  • Laptop diagnostic or PC with the necessary software installed to run the diagnostic tool.

BMW diagnostic software, such as ISTA-D (Integrated Service Engineering Applications – Diagnostics), ISTA-P (Integrated Service Engineering Applications – Programming) or Rheingold.


To be able to fix BMW 801C20 error, you can perform diagnostics by software. Once the fault is identified, you can follow the repair plan. However, you need advice from experienced technicians to get the most suitable repair plan.
The use of software and support facilities will help you save maximum time and effort in the BMW DTC 801C20 repair process.

If you do not have the full software and equipment, you can refer to our BMW diagnostic software or refer to the website. If you have any questions, please contact us by texting through the website or whatsApp +13155472355 for fastest support. Eurocartool is always ready to support 24/7.

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