What Triggers "Pre-Safe Functions Limited" Warning in Mercedes and How to Fix It?

Mercedes-made vehicles are considered the safest… as they come equipped with the best safety systems available to provide the commuters with maximum protection. Today’s blog post sheds light on the ‘Pre-Safe System’―an innovative technology designed to anticipate a collision before it happens.

Mercedes Pre-Safe System, Explained

It is a fully-automated system that continually scans the surrounding environment using cameras and radar sensors―located at strategically important parts of the vehicle. If it finds out that a collision is likely to happen in the next few seconds, it will initiate a safety protocol… to minimize the impact.

The system will adjust the seat position, tighten the seatbelts, automatically close any open windows/ sunroof, initiate emergency braking, and generate a stapedius reflex inducing noise to protect the hearing from the loud sound of a potential crash… the ‘art of saving lives’.

Common Causes of Pre-Safe Function Limited

If your Mercedes is displaying "PRE-SAFE Function Limited See Oper. Manual"message… it simply means one of the components related to the Pre-Safe system is faulty, preventing it from functioning at full capacity. The trigger could be one of many different things, including the following.

#1- Sensor malfunctions

To detect potential hazards around the vehicle, the Pre-Safe system relies on a network of sensors. Real-time data sent by these sensors is what allows the system to anticipate if a collision is imminent… so that it can implement proactive actions to safeguard the occupants. Should any of these sensors malfunction, become dirty, or misaligned, it will hinder the Pre-Safe’s ability to properly predict a potential collision.

#2- Electrical problems

From data transmission to implementation of safety protocols… the vehicle’s electrical architecture helps the Pre-Safe system with many different things. A fault in this architecture could prevent the sensors from communicating with the control module, thereby inhibiting the system’s ability to activate safety measures when the situation demands. To alert you about the issue, the ‘PRE-SAFE Function Limited’ warning will be triggered by the onboard computer.

#3- Software issues

Computers on wheels… that’s what modern-day vehicles are called. To help these computers perform different tasks, millions of lines of code are written… enabling everything from navigation to safety features. Bugs or glitches in the software helping the Pre-Safe execute complex processes can trigger the ‘PRE-SAFE Function Limited’ warning. Compatibility issues resulted from software updates can also set off the alert.

#4- Worn-out components

For Mercedes’ Pre-Safe to be able to execute safety protocols in the event of an accident… a lot of things need to work in harmony, including sensors, software, and hardware systems. As the hardware systems age, they become vulnerable to wear and tear. Fault in such components may prevent the Pre-Safe from deploying safety mechanisms when needed, resulting in the activation of the ‘Functions Limited’ warning.

#5- Other mechanical issues

The Pre-Safe feature rely on critical systems such as brakes, suspension, and the airbag system to make sure that the passengers stay protected in the event of an imminent collision. Should any of these mechanical systems experience issues, the Pre-Safe system’s performance will suffer and the ‘Function Limited’ alert will be activated.

How to Fix "Pre-Safe Functions Limited

1. Restart the vehicle: This will refresh the system and clear any minor errors that might have triggered the warning.
2. Check the sensors and cameras: Clean them using a soft cloth and pH-neutral cleaning agent if they are covered with dust.
3. Electrical and software checks: Carefully examine the wires and connectors in the circuit for corrosion and visible damage marks. Consider updating the software to the latest version.
4. Resetting the system: Proven way to eliminate persistent errors affecting the Pre-Safe feature’s operations.

#5- Visiting authorized service center to have the issue assessed by certified professionals.

Summing Up

If your Mercedes displays "PRE-SAFE Function Limited See Oper. Manual" message on its Dashboard, it simply means the mechanism responsible for protecting the occupants in the event of a collision has encountered an issue. It could be anything… from a faulty sensor to a corroded wire. Fortunately, there are ways to get rid of this alert. Sometimes it is as easy as restarting the vehicle. Resetting the system is yet another proven solution that can restore the Pre-Safe system’s functionality.

M Service, INC. is one of the most popular auto repair shops in the Walnut Creek area that is having years of experience in looking after European cars Land Rover, Audi, BMW, Mini, Mercedes, and Porsche. At M Service, INC.