[Myk-D]

I was driving along a dual carriageway yesterday afternoon (in London) at approx. 50mph when my X3 suddenly slammed the brakes on and a warning came up on the screen, something along the lines of "Hazard: Broken Down Vehicle". My passenger and I were both thrown against the seatbelts hard - as you can imagine it was quite a shock, and I've no idea how the guy behind didn't plough into me. There was nothing in the road in front of us, and I was a good distance behind the car in front (which hadn't slowed down or anything).

The only reason I can think of for this is that the traffic going in the other direction had come to a standstill, so I'm guessing that for some reason my car detected the stopped traffic on the other side and thought it was in my lane.

Anyone else had this? I'm a bit shocked as it was pretty dangerous.

[dagneto]

i've read on somewhere that someone had a similar experience. i personally haven't experienced it. we thought it may be linked to the sensors detecting possible collisons

[BMWGuySweden]

wow this makes me want to drive with all assistant systems off

[tenflyer]

Were you driving at a sharp corner where the stopped traffic in the other lane would have been in the line of sight? This has never happened to me either, and hopefully never will.

[Pretzel]

Very troubling. Glad it didn't cause a crash and no one was injured.

Driving through the city I tried to turn off pedestrian collision due to people frequently standing by the edge of crosswalks on busy streets. I was accessing the settings via the safety button and it said something like this couldn't be turned off?

[Boosh99]

Originally Posted by Myk-D

I was driving along a dual carriageway yesterday afternoon (in London) at approx. 50mph when my X3 suddenly slammed the brakes on

...

Anyone else had this? I'm a bit shocked as it was pretty dangerous.

Not quite the same and only had the car for a few days, but driving along and there was an undulating road (almost like a bump) and the car started to brake (was on active/adaptive cruise control). Wasn't an emergency stop, but was surprised that it was braking. I'm not yet familiar enough with this system, but had one or two instances of similar things across 4 years with my 2013 Audi 8V S3, so hopefully it will be as infrequent (or less) than this in my X3.

[sor]

This is a good read that gives a high level overview about how these systems work and how hard it is to get them to be reliable. I'm actually surprised the system actually functioned at that speed, the automatic emergency braking should be disabled at 50mph.

https://arstechnica.com/cars/2018/06...lane-dividers/

[Myk-D]

Originally Posted by tenflyer

Were you driving at a sharp corner where the stopped traffic in the other lane would have been in the line of sight?

No, I could have understood the sensors being mistaken in this instance, but the road was straight.

[Myk-D]

Originally Posted by sor

This is a good read that gives a high level overview about how these systems work and how hard it is to get them to be reliable. I'm actually surprised the system actually functioned at that speed, the automatic emergency braking should be disabled at 50mph.

https://arstechnica.com/cars/2018/06...lane-dividers/

Thanks for this. I fully understand how difficult it must be to get these systems to work reliably, with all the possible variables you have in everyday, city driving.

I'm hoping it's a one-off based around the sensors making a mistake due to the traffic conditions, rather than a fault (either in the sensors or in the programming). It's bit concerning though as it could have easily ended in an accident.

[nosnoop]

Were you on adaptive cruise control?

[Myk-D]

Originally Posted by nosnoop

Were you on adaptive cruise control?

No, I don't have it. I had the limiter on (set to 55, but I was under it) as I was in a 50mph average speed-check zone and didn't want to stray too far over the limit.

[nosnoop]

Originally Posted by Myk-D

I'm hoping it's a one-off based around the sensors making a mistake due to the traffic conditions, rather than a fault (either in the sensors or in the programming). It's bit concerning though as it could have easily ended in an accident.

You definitely should let BMW know about this.
You should report this to your dealership, which probably has no clue about what went wrong and make up an excuse to explain it away.
So you should also report this BMW UK. Hopefully they would listen to you, and if there is bug in the system, they can fix it.

[Lolpop89]

Originally Posted by Myk-D

I was driving along a dual carriageway yesterday afternoon (in London) at approx. 50mph when my X3 suddenly slammed the brakes on and a warning came up on the screen, something along the lines of "Hazard: Broken Down Vehicle". My passenger and I were both thrown against the seatbelts hard - as you can imagine it was quite a shock, and I've no idea how the guy behind didn't plough into me. There was nothing in the road in front of us, and I was a good distance behind the car in front (which hadn't slowed down or anything).

The only reason I can think of for this is that the traffic going in the other direction had come to a standstill, so I'm guessing that for some reason my car detected the stopped traffic on the other side and thought it was in my lane.

Anyone else had this? I'm a bit shocked as it was pretty dangerous.

Sorry as this is an old threat but I'm having major issues with this at the moment and was wondering if you reported it to BMW or sent it in for them to look at?

[Gritty]

I'm not saying that this is your issue... I have had a few sensor glitches while driving in snowy /icing conditions. It's very important in these new cars to keep the sensor and camera areas clean. I suspect dirt and mud would also cause an issue.

We don't always have time to wash the car but it is important between washes to walk around the vehicle with a damp rag and clean the sensors and cameras areas.

[moff]

Originally Posted by Pretzel

Very troubling. Glad it didn't cause a crash and no one was injured.

Driving through the city I tried to turn off pedestrian collision due to people frequently standing by the edge of crosswalks on busy streets. I was accessing the settings via the safety button and it said something like this couldn't be turned off?

Just hold down the button for 30 secs and all aids will switch off.

[harperium]

These systems are all radar based and occasionally misread. I’ve had the sudden stop happen a few times. Once it wouldn’t let me back up - had to drive forward first.

On the other hand, a few months ago the system totally worked and emergency braked when a pedestrian ran in front of my car at 22 mph.

[prolix21]

This wasn't in an X3, but we have a Golf Alltrack which has a lot of the same type of systems and we've had it mis-read situations and emergency brake or do various other odd things when in traffic, or suddenly slow down while in adaptive cruise when there's nothing going on. Just some additional info, as I think the issues isn't limited to any specific make/model- the tech isn't 100%

[foglem]

Ironically mine (M40i) just did this yesterday too. Snow melting on the roads is getting kicked up by cars in front and dirtying the front end/radar sensors. I have to assume that's the issue, but dang is it scary when the car just slams on it's own brakes. Dunno if I want to bother reporting it though as it was overall a non-issue for me.

[Gritty]

Originally Posted by prolix21

This wasn't in an X3, but we have a Golf Alltrack which has a lot of the same type of systems and we've had it mis-read situations and emergency brake or do various other odd things when in traffic, or suddenly slow down while in adaptive cruise when there's nothing going on. Just some additional info, as I think the issues isn't limited to any specific make/model- the tech isn't 100%

Agreed. I had a few issues while driving a Volvo V90 rental car. It was very sensitive when backing up even when the other car was across the street. It's a real jolt when it locked up the brakes

[Harmon]

I joined this group just for this issue!
It has happened twice in two weeks to my girlfriend while driving our new X3. Both times straight road and (thank god) no other cars around. We live in the country so no pedestrians. She scheduled an appointment with BMW. The service lady said she has been hearing this a lot. I am finding this unacceptable and disconcerting. The thing is turned off now.

I would urge anyone else having this problem to report it so BMW can get on a fix. When they get someone hurt or killed they can't say they didn't know.

[sys1820]

Originally Posted by Myk-D

I was driving along a dual carriageway yesterday afternoon (in London) at approx. 50mph when my X3 suddenly slammed the brakes on and a warning came up on the screen, something along the lines of "Hazard: Broken Down Vehicle". My passenger and I were both thrown against the seatbelts hard - as you can imagine it was quite a shock, and I've no idea how the guy behind didn't plough into me. There was nothing in the road in front of us, and I was a good distance behind the car in front (which hadn't slowed down or anything).

The only reason I can think of for this is that the traffic going in the other direction had come to a standstill, so I'm guessing that for some reason my car detected the stopped traffic on the other side and thought it was in my lane.

Anyone else had this? I'm a bit shocked as it was pretty dangerous.

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I know your situation.
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You send messages to me.
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[DAC17]

We were in a way better place when people simply paid attention to their driving. Every one of these passive "safety features" causes people to subtly and inadvertently pay less attention to their driving. Besides blind spot monitoring and rear camera systems, the rest of these will tend to encourage less attentive driving.