A Pre Safe Functions Limited is a warning message showing a malfunction in the pre safe system installed in your Mercedes car. It is an in-house security technology designed to reduce the damage during accidents.
During an accident, The pre safe system functions to reduce driver and passenger injuries. Sometimes, the system can even stop any accident or crash from happening on the road. It does not come as a standard feature and is now available on select Mercedes models only, such as Mercedes B Class, Mercedes A Class, 2014 Mercedes-Benz CLA 250, 2014 Mercedes CLS e350, Mercedes E class, Mercedes A 180, Mercedes X class, and Mercedes-Benz SL models.
What Does PRE-SAFE Function Limited Warning Message Mean?
If you ever see the warning message pre safe function limited on your Mercedes, it means that there is some error in the pre safe system. It may be due to many factors, such as a Mercedes malfunction or system software problem. It can affect the radar sensor in front of your car. Some of these problems are dirt, trash, or damaged by humidity.
A warning message could also appear on your screen when you drive in heavy rains or snowy or dusty roads. The snow or ice could block the radar, seriously affecting the operation of the pre Safe system.
The main purpose of the PRE-SAFE Function Limited warning message is to tell you about the malfunction of the system, and it must be handled carefully. Firstly, you should analyze the sensor’s problem. When you find any error, try to fix it.
If this message keeps showing up, it’s time to contact a qualified technician to fix the issue as soon as possible. The pre safe system may need to be repaired or removed depending on the reason.
Why Is My Mercedes Benz Not Working?
1. Warning Message Limited
The advanced PRE-SAFE system consists of many interconnected parts, which makes it more prone to errors due to its complexity. It could be because of programming issues or instruments needing cleaning. Let’s explore some most common reasons why your Mercedes-Benz might show the pre-safe function limited warning.
2. Malfunction of the Software
The software is essential for the pre safe system to react correctly to the radar sensor’s incoming data. Even though the program was carefully made, it is almost impossible to fix every problem. Moreover, the software might not be able to adjust to real world changes effectively.
The majority of pre-safe function limited alarms are as a result of software glitches or bugs. Luckily, the problem should be fixed by installing the latest Mercedes software update. Getting help is easy. Just drive to the nearest store.
3. Bad Sensors
A group of radar devices on your car’s front bumper make up the main part of the pre Safe system. On rough roads, these devices could get dirty or blocked by things. More than half of drivers have noticed that the pre-safe function limited warning sign appears on the screen when the road is too wet, dusty, or slippery. You might have the same thing happen. There could be something blocking the radar that is setting off the warning.
To remove the message, you can clean the devices. This will get rid of any dirt or snow that is on the sensors.
4. Water Droplets Form Between the Plastic and Sensors
Similar to a camera, a radar monitor must have a clear line of sight to work correctly. Early morning, water building up under the front bumper could make it harder for radar to pick up on anything ahead of the car. If there is a problem with the sensors, the part that controls the car’s safety systems will let you know through the indicator panel.
5. Control Module
The computer that reads the data from the radar devices and controls the motors is called a control module. You could fix the front seat belts, shut the windows and sunroof, press down on the brakes, and so on. The pre safe system can’t work because a part is broken.
A knowledgeable driver should inspect the control box for the important information. Have a trained mechanic or shop look at the control box for the best results. There is no other way. The pre-safe Function Limited warning appears infrequently, which is good.
6. Sensors with Loose Connections
The monitors around your car are vital for the PRE-SAFE system to work. Keep the monitors hooked up to the bus at all times to get the necessary information. An open circuit could happen in the system if the wires that connect the parts rust or break over time.
Ensure all of the links on the wire harness that sends power to the system’s sensors are tight. Read the owner’s repair manual to find out where each monitor is and how to connect it. If you know how to fix things around the house, you could fix this yourself, but it shouldn’t cost too much to have a skilled shop do it.
7. Tightening the Bolts on the Throttle Body Switch
What does the Mercedes warning light that says stop vehicle leave engine running mean? This could be because the throttle body switch plug is not tight enough. Mercedes-Benzes will turn off the pre safe system and show a warning sign if the throttle body wiring wire link plug doesn’t make good contact.
There are often other warning lights on top of the warning light. The traction control and anti-lock brake systems get their information from the throttle body. Making sure that the links are tight and free of rust is a good idea.
8. ESP and ABS Systems
Even if the electronic stability plan (ESP) or anti-lock braking system (ABS) doesn’t work right, the pre safe system might still work in some ways. Some of the most common reasons are ESP control units that don’t work right and broken wheel speed monitors. The ESP and ABS have problem codes that are saved. You can get them from a diagnostic tool. As soon as these problems are fixed, the pre safe system might start working again, and the warning message will disappear.
Where is Mercedes Pre Safe Sensors Located?
Mercedes-Benz Pre Safe prepares the car and its passengers ready for a crash. It uses many sensors and technology to detect unsafe driving situations and reduce harm.
| Sensor Type | Functionality | Typical Location |
| Radar Sensors | Adaptive cruise control, collision avoidance | Behind front grille/bumper |
| Cameras | Lane departure warning, pedestrian detection | Near rearview mirror/windshield |
| Ultrasonic Sensors | Parking assistance, blind spot monitoring | Front and rear bumpers |
| Accelerometers | Measure acceleration/deceleration | Within chassis/body structure |
| Steering Angle | Monitor steering input | Steering column |
Conclusion
The pre safe system is a safety feature on selected models of Mercedes. It functions for the safety of the driver, and passengers during accidents. It is designed to work with other auto systems, such as added radar systems, ABS, and sensors, to deliver. Any malfunctions in any of these systems will result in a Pre-Safe Function Limited warning message. You should immediately fix this problem by a trained technician for safety concerns.
