Mercedes anti theft protection activated

Mercedes-Benz Anti-theft Protection Activated Quick Fix

Mercedes-Benz Anti-theft Protection Activated is a security feature available in some Mercedes-Benz vehicles. It is designed to help prevent theft of the vehicle by activating an alarm system and disabling the engine starting system and radio. When activated, the system will arm itself automatically after a certain period of time or when the vehicle is locked. In some cases, the vehicle will start but the radio or the COMAND screen will show anti-theft protection activated which can be due to a glitch in the vehicle communication network or a weak battery, in this guide we show you how to reset it. The Anti-theft Protection Activated feature is intended to provide an additional layer of protection for your vehicle and can help deter thieves from attempting to steal it.

When you turn on the Mercedes-Benz Comand system, a message appears on the screen, indicating that the “Anti-theft protection” is activated. At this point, the entire system stops working, including all audio, navigation, and other features. Fortunately, the car continues to function normally. The car was probably locked overnight, and you unlock it using the fob before starting it up. However, approximately five seconds after starting the car, the anti-theft protection activated message appears on both the dash display and the larger Audio 20 display. As a result, you cannot access any of the system’s features, such as the phone, radio, or media playback.


Mercedes Anti Theft System Activated No Radio Command or Sound
  • Antitheft protection activated, switch ignition on, and restart the system
  • Anti-theft protection is activated, please switch the ignition on and restart the system
  • Anti-theft protection activated please visit your Mercedes-Benz workshop

Common Causes

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The most common causes that trigger the Anti-theft protection activated” mode on Mercedes-Benz vehicles include:

  • Weak car battery – The “Anti-theft protection activated” message on a Mercedes COMAND screen can also be caused by the vehicle’s battery, which is located under the hood, under the seat, or trunk depending on the model. In colder weather, if the car is parked overnight, or if the battery is old, it may not hold a full charge. This can cause the voltage to drop below the required threshold, which is 11.5 volts. If the voltage dips below this level, the alarm system may activate, triggering the anti-theft protection message.
  • Replaced Radio / Command / Head Unit
  • You tried to change the region in the Engineering Menu.
  • Communications loss between the Command system and the car due to a damaged wire harness.
  • EIS (electronic ignition switch) is replaced and not coded correctly. To fix this problem properly code the new EIS and the COMAND unit.

Car Battery May be Getting Weak

Replace Battery on Mercedes-Benz GLK

Mercedes’s “Anti-theft protection activated” message on the COMAND screen can be caused by several factors, one of which is a weak battery that is not holding a full charge. Over time, the battery in a vehicle can become old and begin to lose its ability to hold a charge. If the battery voltage drops too low during startup, it can cause a disruption in the internal network of the vehicle, which can trigger the anti-theft protection.

The COMAND system requires a stable and adequate power supply to function properly. If the battery is unable to provide sufficient power, the COMAND may not be able to detect the CAN network of the vehicle, and the anti-theft protection will be activated. Therefore, it’s essential to regularly check the health of your car’s battery and replace it if necessary, to ensure that it’s functioning correctly and providing sufficient power to the vehicle’s systems.

Quick Fix

reset anti theft protection activated 1

To resume the operation of your COMAND unit and disable the anti-theft protection, you can either press and hold the power button for ten seconds or restart your vehicle. This will typically restart the COMAND and allow you to use features such as radio and navigation. If the issue persists, try rebooting the COMAND by turning off the engine, locking the vehicle with the key fob, waiting five seconds, unlocking the vehicle, and starting the engine before turning on the COMAND. If neither of these solutions works, we recommend scanning for codes on the COMAND.

Further Troubleshooting


For a thorough analysis of the fault codes on your COMMAND unit, we recommend using the YOUCANIC full system scanner to perform a comprehensive scan. If multiple codes are detected, we suggest saving the report and clearing all codes before focusing on the codes that reappear.

When reading the codes with the YOUCANIC scanner you may find current codes such as the fault code 9561 or B156100 “The PIN for the anti-theft protection is incorrect or absent” is current and/or stored in the diagnostics quick test. See this troubleshooting guide from Mercedes-Benz Xentry Tips.


Mercedes-Benz Anti-theft Protection Activated is a security feature available in Mercedes-Benz vehicles that are designed to help prevent theft of the vehicle. This feature can activate an alarm system and disable the engine starting system when someone tries to open the doors, trunk, or hood without using the proper key or remote or when someone tries to start the engine without using the correct key or remote. If you encounter the message “Anti-theft Protection Activated” on your Mercedes-Benz, it is recommended to visit your nearest Mercedes-Benz workshop for assistance. Overall, Mercedes-Benz Anti-theft Protection Activated can provide additional security for your vehicle and help deter potential thieves.

Possible Fault Codes

  • 0607 The control unit has a malfunction.
  • 94D9 The internal hard disk has a malfunction.
  • A19C The wake-up line has a short circuit to the ground.
  • A19D The wake-up line has a short circuit to positive.
  • D016 MOST communication has a malfunction (the position of the ring break cannot be identified).
  • D017 MOST communication has a malfunction (MOST master reporting ring break).
  • D180 The display screen is faulty.
  • D181 The background illumination of the control unit COMAND or AUDIO is defective.
  • DA00 Enabling the Audio or COMAND is not possible due to a CAN fault.
  • DA01 Anti-theft protection is activated (the control unit is disabled).
  • 9536 An unauthorized mobile phone cradle is installed.
  • A10A The power supply in the system is too low.
  • A10B The power supply in the system is too high.
  • A10D The power supply is too low.
  • A10E The power supply is too high.
  • A27B The specified and actual configurations of the MOST components are different.
  • A27D The watchdog function has detected an internal software error.
  • C020 Interior CAN bus OFF fault
  • D850 An unknown MOST component is installed.


  • Rushit Hila • ASE Certified

    Rushit Hila, an ASE-certified engineer (G1 Automotive Maintenance and Repair), brings over two decades of hands-on experience in the automotive world to his writing. With a strong educational background, including a Master of Science in Engineering and a Bachelor of Science in Engineering, he has honed his skills and expertise through years of practical work. As a respected authority in the field, Mr. Hila is dedicated to offering insightful and valuable content that resonates with both vehicle owners and mechanics.

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