The Mercedes Benz Collision Prevention Assist Plus is a useful feature in many models for helping drivers avoid collisions on the road. It displays a red warning message on dashboard when you are approaching vehicle in front of you too fast and starts to make some beeping noises and if necessary collision prevention assistant applies braking in an emergency when a vehicle veers too close to another. A common error message on the dashboard is the "Collision Prevention Assist Plus inoperative" message. Read on to find out what can cause this and how to fix the problem.

collision Prevention Assist Plus Inoperative Message

What is Mercedes-Benz Collision Prevention Assist Plus?

This is brand new technology created by Daimler to ensure there are less and less accidents on the road while driving and driver doesn't pay attention what's happening in front of him or is being distracted.

System works by using short range radarsensor in front on the car, under bumper near number plate. It is small black box called radar sensor and when car is turned on it scans what is happening in front of you.

For example if you driving in the highway and approaching another car in front you too fast it will pop red warning message in instrument cluster to warn you to keep distance between you and other vehicle to avoid collision, if you don't take any further actions and slow down it will keep displaying that warning or if you continue to increase your speed it will start to beep and if you continue for any reason to keep accelerating or vehicle in front of you starts to apply brakes, your mercedes-benz car will immidiatelly start braking as well to avoid collsion or at least to minimize any damage.

In addition this system is amazing when you are start moving, for example if you have stopped at red light and light changes to green you start moving and a car in front of you suddenly applies braking and you are distracted it will instantly brake to avoid collision into rear of other motor vehicle.

Collision Prevent Assist Plus is right now being fitted to all Mercedes-Benz cars made from approximatelly 2015 and onwards and it is manditory system to have by law for new cars, will be installed without any charge as default option.

Can I deactivate or turn off Collision Assist Plus ?

The answer yes, ofcourse! But why? It is completely not worth deactiving this feature as it is super helpfull in helping to avoid rear bumping into other vehicle.

But if in any case you would like to disable this amazing feature you can do that using your steering wheel and navigation buttons on it, click on home button next navigate to assistance and there are collision assist plus, then you can choose to completely disable it or choose level of sensitivity which you prefer, the less sensitive it is the less warning messages it will display, unless it is very close to collision situation.

What does the warning error message mean?

The "Collision Prevention Assist Plus inoperative" message simply means that the feature has stopped working and the car will not only cease to detect possible collisions but will not be able to automatically apply the brakes. Other issues can arise alongside this message which will render the vehicle unsafe or difficult to continue driving, such as trouble using the gas pedal and trying to accelerate.

Ofcourse you can drive your car for unlimited time, it is not the most important malfunction, but we still recommend to try to fix as soon as possible.

Why does my collision prevention system change to inoperable?

Collision prevention assist plus feature changes to inoperable by finding malfunction in the system, it might be software or mechanical part.

To try to enable collision asssist again stop your car, leave off for 20minutes try to turn and check for warning message again, if it still there check front bumber if it has any damage, dirt, snow or other debris - if you did find something, clean it and try again.

If after doing above two steps you weren't able to fix it is most likely that radar sensor has failed, so remove front bumber and check sensor if needed replace it.

How to fix it?

Firstly, always stay alert and aware while on the road; keep a safe distance from other vehicles and find a safe place to pull over and turn the engine off. A low battery or extreme outside temperature can affect the sensors, so restarting the car can reboot the system after which it should work fine. Leaving the car to idle for 10-15 minutes can often help it recharge enough for the system to kick back in.

If restarting doesn't work, check the front bumper where the sensors sit; if it is covered in debris such as dirt or ice, clear it off to unblock the sensors and restart the car to allow them to read the road.

Another fix in the list should be clearining error codes using star xentry software or any other software, but ofcourse dealer software is always the best. Try simple to clear the memory of the car as in many cases it helps as well and the reason is because car has ECU (computer) and like any other electronic computer it does calculations and keeps stocking many information and sometimes it just gets clogged and that's why simple clear fault codes help.

After you've tried these the cheapest ways to fix warning message, let's go to the mechanical part. Carefully remove front bumper from the car, once removed you will see like a black box like a smart phone (it's radar sensor) attached on the bamber with clips. Gently unplug wires and take a look if there is any moisture on both connectors, car's and sensor itself if there is, it is a tell tell sign that sensor has been damaged by water or moisture and needs to replaced in order to fix warning message, another sign when mercedes-benz radar sensor needs to be replaced is damage to sensor itself, for example collision or bad smell coming out of part, it also means part has had some kind of short circuit and burnt.

Bear in mind that every electrical part has it's life-time and it is normal that radar sensors fails.

Finally, if you did all the checks and options above and still seeing "collision assist plus inoperative" message it might be that car's software may need updating. Locate a Mercedes Benz dealer and ask them to update the software for you to ensure the system is running smoothly and it is up-to-date.

For those with a diagnostic system scanner and some technological know-how, scanning the system for Mercedes Benz fault codes can diagnose and clear other problems.

More information about mercedes-benz radar sensors

The main supplier for Mercedes-Benz radar sensors are Sweden based company Autoliv ASP Inc. Company supplies many different kind of sensors for mercedes cars such collision warning, distronic plus, blind spot assist, lane keeping assist and many other.

As always Xenons4U blogs provide you free guides how to diagnose faulty parts and various malfunctions as well as how to fix them, which part numbers and cars it does fit. A list of compatible radarsensors and car models could be found below of this blog.

Radarsensor part, software and hardware numbers:

  • A000905490764
  • 000-905-49-07-64
  • ZB A0009054907
  • SW A0009024035
  • HW A0009018504
  • ZB A0009058702
  • SW A0009026613
  • HW A0009056700
  • 000-905-28-06
  • ZB A0009052806
  • SW A0009029029
  • HW A0009013503
  • 000-905-49-07
  • ZB A0009054907
  • SW A0009024035
  • HW A0009018504
  • 000-905-84-06
  • ZB A0009058406 SW A0009026932 HW A0009018504
  • A2319055302
  • 231-905-53-02
  • ZB A0009052804 SW A0009020721 HW A0009013503
  • A0009050802 SW A0009026410 HW A0009016002
  • A0009051704 SW A0009027120 HW A0009016002

Mercedes-Benz cars fitted with collision assist plus:

  • C-class W205 Saloon Sedan
  • C-class S205 Estate
  • C-class A205 Convertible Cabriolet
  • C-class C205 Coupe
  • C Class C180 C200 C220 BlueTec C250 C300 C350e C400 4MATIC C450 C43 C450 C63 AMG
  • SL R231 SL450 SL550 SL63 AMG
  • CLS W218 C218 CLS550 CLS63 AMG
  • SLK R172
  • CLA C117 Coupe X117 Shooting Brake
  • CLA220d CLA250 CLA45 AMG
  • GLC X253 C253 W253 Hatchback Coupe 2015 2016 2017 2018 2019
  • GLC GLC300 GLC350e GLC220d GLC 220d GLC250d GLC350d GLC300 4 MATIC GLC43 GLC63 AMG
  • GLA X156 GLA220d GLA250 GLA45 AMG
  • GLS X166 GLS450
  • AMG GT C190 R190
  • ML GLE W166
  • ML C292 Coupe
  • GLE350 GLE400 GLE550e GLE43 GLE63 AMG
  • B-class W242 W246
  • A-class W176
  • A class W177 Sedan Saloon Hatchback
  • A160 A160d A180 A180d A200 A200d A220 A220d A250e A35 A45 AMG 4MaticS-class W222 Saloon Sedan
  • S-class C217 Coupe
  • S-class A217 Convertible Cabriolet
  • S class S350 S400 Hybrid S500 S600 S300 BlueTEC S350 4Matic S550 S63 AMG, S65 AMG
  • E-class W212 S212 A207 C207 Facelift 2014 2015 2016 2017
  • E-class W213 S213 2016, 2017, 2018, 2019
  • E-class Coupe C238 2016, 2017, 2018, 2019
  • E-class Convertible A238 2017, 2018, 2019
  • E-class E200 E250 E300 E350e Hybrid E400 E450 E200d E220d E300d E350d E400d 4MATIC E43 AMG
  • CLS Class Coupe C257 2018, 2019
  • G Class W463 2018, 2019

At Xenons4U, we provide high-quality parts at fantastic prices, and you can contact us for more expert help with your Mercedes Benz, or browse our range of OEM or aftermarket Mercedes Benz parts and if you liked and found out this blog usefull please share on social media and with your friends.