SCARY Active Brake Assist malfunction?
I started a thread so we can get a head count on people with this issue, across different platforms. If your car's having this problem, please post here:
https://mbworld.org/forums/mercedes-...ml#post7833418
The warning tone sounded, our seatbelts cinched tightly and the car braked so strongly that you could feel the ABS kick in. It all happened in an instant and then it was over. I believe that I may have tromped on the brake pedal as well, just as a reflex, but it all happened so fast, that I really don’t remember all the details. I looked to see if we had run over anything, but there was nothing. We continued about two miles to our destination, where I examined the car, but there was no sign of anything out of the ordinary. Only a few, small bugs on the plastic Distronic sensor.
I have to tell you that my wife screamed and this event scared the hell out of me. The car has operated perfectly since this happened and I used Distronic most of the way on our drive home. Did the system just hiccup or??? Has anyone else ever experienced this? I plan on taking the car into the dealer this week and having it checked out. Scary!




I had to step on the gas and override it so that I did not get creamed by traffic behind me. It felt like about a 40% brake application - so not as hard as yours, but a big surprise to me and an unwelcome one at that.
No issues since then and I am steering a bit further away from anything as I make lane changes with Distronic on. I chalked it up to tech that is helpful, but imperfect, but like you, I sure didn't appreciate it.
I had to step on the gas and override it so that I did not get creamed by traffic behind me. It felt like about a 40% brake application - so not as hard as yours, but a big surprise to me and an unwelcome one at that.
No issues since then and I am steering a bit further away from anything as I make lane changes with Distronic on. I chalked it up to tech that is helpful, but imperfect, but like you, I sure didn't appreciate it.
The Best of Mercedes & AMG




The warning tone sounded, our seatbelts cinched tightly and the car braked so strongly that you could feel the ABS kick in. It all happened in an instant and then it was over. I believe that I may have tromped on the brake pedal as well, just as a reflex, but it all happened so fast, that I really don’t remember all the details. I looked to see if we had run over anything, but there was nothing. We continued about two miles to our destination, where I examined the car, but there was no sign of anything out of the ordinary. Only a few, small bugs on the plastic Distronic sensor.
I have to tell you that my wife screamed and this event scared the hell out of me. The car has operated perfectly since this happened and I used Distronic most of the way on our drive home. Did the system just hiccup or??? Has anyone else ever experienced this? I plan on taking the car into the dealer this week and having it checked out. Scary!
Last edited by Ursula2365; Jul 24, 2021 at 10:36 AM.
Dealership has my GLS450 and I have heard very little back since Tuesday. One phone call saying that they are sending info to engineers. I asked about my incident recorder in the car and the mgr said only a few faults showed up but nothing related to my incident. One related to a garage door. Interesting as I do not use a garage door opener through my car. But he said the engineers will ask for more information that perhaps he cannot see on his side. I was sure that it would have recorded this incident, but now I am worried as it doesn't seem to show much except for something that doesn't even pertain to my car.
On another note, I purchased this car in April 2021. One month after, my entire front panel went out on me. I was in Michigan and had to drive home without any use of the entire panel. Fortunately I know old school driving. The module was replaced but since then my navigation is completely useless and malfunctioning. Most of the time doesn't recognize address. Sometimes sends me to all parts US but not what I need. Once I finally get the correct address it continually tries to reroute me off highways and tollways (and no I do not have that checked as requested, I check every time). Reroutes me even when the location is within my sight. This has been confirmed by other people in my car watching the car taking me in circles. I have called twice on this with very little explanation and no resolution. I have had to drive to NYC and NJ using apple carplay navigation as I cannot trust the navigation in my car. Same as you, I am about finished with this car three months in. Need to break the lease. I feel safer in my 5 year old jeep.
I am going to file a complaint on the nhtsa.gov website with regards to the abrupt braking just incase this is happening to other people and they are looking for information. Perhaps you will want to do the same. Please keep me posted on what your MB dealer says.
Good luck to you all in getting this fixed, execute your rights and if you live in the USA, perhaps even start a lemon law claim if you meet the criteria.
Last edited by W205C43PFL; Jul 24, 2021 at 08:27 PM.
I think this kind of malfunction is just always a possibility with this type of system.
I think this kind of malfunction is just always a possibility with this type of system.
Not sure what happens next.






