Mercedes Pre-Safe Functions Limited Cause & Fix [Explained]

Safety on the road is a significant concern for both passengers and drivers and is always a priority. Therefore, vehicle companies develop high-tech protective systems to ensure road safety.

“PRESAFE System” is one of them, founded by the Mercedes community. This function provides the maximum protection to you and others on the road. 

MB has installed that or made “Mercedes Pre-Safe Functions Limited” available for these models that I’ve noted down in the table:

What Does A PRESAFE Function Mean?

A function that prepares a vehicle for an impending collision is called the PRE-SAFE® function. With the help of different sensors, the safety of your vehicle’s occupants is ensured by automatic measures.

Mercedes Pre-Safe Functions Limited: Causes

Also Read: Mercedes-benz ESP inoperative warning light, Its causes and reset

What are the features of a pre-safe Mercedes-Benz?

Pre-safe systems prevent accidents and decrease their consequences. That function monitors the vehicle’s behavior and tracks the driver’s actions. 

Here are these preventing actions that it will perform in case of any possibility of a car crash or loss of control:

1. In case of a rollover, the windows and sunroof will close automatically, stopping large debris from entering the vehicle. As a result, prevent windows from closing on the fingers of the passengers’ windows will not roll up.
2. Inside the calipers, the brakes raise the pressure, increasing the braking force and improving the vehicle’s stopping action. This action ensures that the car slows down as much as possible.
3. During braking, the vehicle will tie up the seat belts to support the passenger against the seat, and the system will also reposition the backrests in the upright position. These functions will ensure a favorable body position if the crash happens unluckily.
4. While braking, the system will automatically activate the hazard lights. This action warns other drivers about a sudden stop coming to the vehicle.
5. Lastly, during a crash, the vehicle’s audio system automatically generates a powerful buzzing sound to prevent hearing damage from loud noises.

All these features aim to prepare a vehicle for a potential impact. In accidents, these matrixes reduce the risk of injury for both (driver and passengers).

It is essential to know that some vehicles have an additional safety feature called Pre-Safe Brake. If the driver fails to react immediately, this protection feature applies automatic brakes to prevent or decrease the chances of accidents.

What Is PRESAFE® Sound?

If your vehicle detects an unavoidable collision, a sound is activated, known as the Pre-Safe sound in Mercedes. In that scenario, the vehicle sound system plays a short intrusion signal called “pink noise” or “pink sound.”

What Is PRESAFE® Brake?

PRE-SAFE® Brake is a sovereign emergency braking system that uses radar sensors to help identify critical situations for vehicles. If the critical situation continuously develops but the driver doesn’t react, the car applies a partial brake for about one and a half seconds.

How Does The PRE-SAFE® Safety System Work?

This advanced protection system relies on drivetrain systems and several other vehicle safety. It uses data from these systems to collect all the necessary information for its operations. 

That function monitors inputs and drivers and constantly looks for signs of panic braking. This happens when the driver releases the throttle and slams the brakes suddenly and sharply. 

Measuring the signs of a potential accident that can happen with skidding and sliding is also a significant factor. Pre-safe systems use wheel speed sensors and Mercedes ABS/ESP system data.

The forward-facing cameras and a series of radars fixed in their windshields also help the PRESAFE system to gain perception. 

By collecting and combining extensive data from these sources, the system will recognize potential issues or obstacles and take immediate action before they occur.

Why Does This Warning Message Occur On The MB Dash?

Pre-Safe is a complex safety-critical system. The slightest irregularity may affect the overall system’s performance, requiring all components to operate optimally and successfully. 

If any malfunction might affect, the vehicle displays a warning message “Pre-Safe functions limited.” These are the most relevant reasons that may cause this:

Control software and its features may be found with affected functions or contain bugs inside its code. In most cases, the software inputs from different sensors seem implausible and cannot handle demanding real-life situations. 

Issues with ABS and ESP systems will limit Pre-Safe’s function and affect its features. Malfunctioning ESP control units and faulty wheel speed sensors are potential topics.

Driving in rugged and harsh situations may cause that operation. Conditions like heavy downpours or snow may affect the function. An unprofessional windshield replacement also can cause these issues.

How To Reset Pre Safe Mode On Mercedes?

Here is the method that you can follow to reset that function on your Mercedes: 

Press and hold the Pre Safe button for a few seconds, then release it. If the warning message continues to appear on the dash, it’s best to seek help from a professional. The system in Mercedes models relies on a network of sensors to detect irregularities.

We’ve thoroughly discussed the “Mercedes Pre-Safe functions limited,” a message that improves the vehicle’s overall safety. It prevents cars from crashing or reduces their consequences. 

It implements several actions using SRS/ABS/ESP, forward-facing cameras, radars, and other systems and hardware. Any failures and issues in these systems will also affect the PRESAFE functions and their performance.