Sudden automatic braking issue (merged, MG4)

[Steve Kaye]

I had 2 similar issues with the emergency braking coming on while i had the automatic cruise control on. ( I have a 2022 ZS EV with 320km range)
Initially I discussed it with the dealer I purchased the vehicle from.
They gave me a load of BS, and basically said it was driver error.
I then contacted the New Zealand importer, told them it wasn't good enough.
They readily agreed to an in warranty check ( at the dealership where I purchased the vehicle from).
End result was: radar was mis aligned, plus they did two software updates ( not sure of the detail)
Learning point is, don't take no for an answer, if you think there is something wrong with your vehicle, there probably is.
If you come at it from a safety perspective, they should get involved in a remedy.
In New Zealand, we also have a Consumer Guarantee Act, amongst other things, the Act says that items must "be fit for purpose".

 

[NLMGSAN]

Did yours come to a complete stand still? Or more like ' a sudden brief braking' ?

 

[jollyman]

Did yours come to a complete stand still? Or more like ' a sudden brief braking' ?

My MG4 se did with a hell of a bang luckily no one else was involved as both incidents were at very slow speed just taking off at around 2-4 mph but it really scares you

 

[NLMGSAN]

My MG4 se did with a hell of a bang luckily no one else was involved as both incidents were at very slow speed just taking off at around 2-4 mph but it really scares you

Interesting... Before they fixed the lidar, if you were overtaking even a bit within the distance range set in ACC and you were in the other lane, did it initially still reduce speed?

 

[Steve Kaye]

Did yours come to a complete stand still? Or more like ' a sudden brief braking' ?

1 instance of a complete stop from 40kmph, scary stuff, and 1 instance of sudden brief braking

 

[NLMGSAN]

1 instance of a complete stop from 40kmph, scary stuff, and 1 instance of sudden brief braking

Did you also experience the car continuing to slow down with ACC on when overtaking a vehicle?

 

[Steve Kaye]

Did you also experience the car continuing to slow down with ACC on when overtaking a vehicle?

Yes at times but that can also mean its working as it should, eg if the car in front of the lane I've just overtaken into slows down in front of me, then clearly I'll slow down too

 

[NLMGSAN]

Yes at times but that can also mean its working as it should, eg if the car in front of the lane I've just overtaken into slows down in front of me, then clearly I'll slow down too

Maybe I should have been more specific: when in the other lane.

 

[securespark]

Not being contentious, just curious; do you think an insurance company would pull a face knowing that two safety features have been deactivated?

On the other side of the coin, would they happily pay out for an accident where a safety system activating contributed to the collision?

I know drivers following traffic should be able to stop in time, but does that still stand where cars are stopping on a sixpence randomly?

I mean, if a case like that went to court and there were witnesses to say there were no obvious reasons why the car jammed on, would the judge apportion blame to the braking vehicle?

 

[siteguru]

I mean, if a case like that went to court and there were witnesses to say there were no obvious reasons why the car jammed on, would the judge apportion blame to the braking vehicle?

It has already happened (not with an MG4 to my knowledge though). I saw it on a dashcam video where the car in front was doing 50 in lane 1 with the dashcam car following, when the front car suddenly slammed on the brakes (with nothing in front and for no apparent reason - the road was dual carriageway and there was nothing overtaking in lane 2) and caused the dashcam car to hit the back of it. The text overlay said it went to court and was treated as a "crash for cash" attempt. (Stupid speed to be attempting that at mind).

 

[securespark]

So your car could cause you an accident which your insurance company then blames you for?



But I guess if you plugged the car in (to diagnostics), it would own up to doing the braking and you would be off the hook?

 

[NLMGSAN]

So your car could cause you an accident which your insurance company then blames you for?



But I guess if you plugged the car in (to diagnostics), it would own up to doing the braking and you would be off the hook?

If the log is saved...

 

[brilig]

Happened to me too! At a very slow speed brakes banged to a stop for no reason!

 

[Rolfe]

I'm always wary of this "shouldn't slam on the brakes for no apparent reason" position. Some time in the 1980s I was driving my Fiesta when my eyesight suddenly faded to nothing. I literally couldn't see. As it happens I was driving on a straight road between two lines of traffic cones - roadworks. I was able to brake relatively slowly and come to a stop, no need to slam on the brakes. I sat for a few seconds and my eyesight cleared. I have no idea what the driver behind me thought. It's never happened again. I suspect a transient functional hypoglycaemia (I'm not diabetic).

If that can happen to a healthy 30-something, it can happen to anyone. Never mind heart attacks and so on. If the circumstances had been different I'd have had no option but to slam on the brakes and hope for the best. But then if anyone examined me later, they would have found nothing wrong.

A deliberate "crash for cash" scenario, if the circumstantial evidence is strong enough, is certainly an exception where the braking driver should be penalised. But there are a lot of possible reasons for a car having to stop suddenly which aren't appreciable to any onlooker.

 

[Steve 666]

I've never had the emergency brake trigger in my MG5, but it did it once in my previous car (Honda Jazz) - I was in slow traffic going round a roundabout close to a van and it suddenly applied full braking.

Ah I have also moved from a jazz to the 4 and exactly the same happened to me when the jazz was slipping into traffic on an island.
The 4 has only braked once and I was realy impressed as it was a dog making a bolt for the road snatched back by the owner on its lead but the car anticipated the fact and jabbed the brakes for a second.

 

[securespark]

We've had it several times when reversing. The car has jammed on so hard it feels like you've hit something.

 

[YaR]

Lovely bit of emergency braking as I was turning across the opposite lane and into a Tesco car park today. Oncoming traffic was about 100m away, also turning into the car park and slowing down so as a driver I knew I had more than enough time to complete the manoeuvre. Emergency brake jams on just as I'm crossing the lane markings and the car refused to move for a good 10s causing an obstruction to traffic in both directions. This is not acceptable. No safety feature should put you in unsafe situations.

Since I got the software updates at the one year service the emergency braking is actually worse. Sometimes it even kicks in as I'm trying to park and slowly moving close to the stationary car in front.

 

[securespark]

It kicked in for us when reversing into a parking space in a car park adjacent to a road. It must have seen the passing traffic and braked.

That's happened a few times now and each time, the braking is so severe, it feels like we've hit something.

 

[AndyL61]

Set the AEB sensitivity to low. This setting stays set and only brakes if absolutely necessary. No phantom braking with sensitivity set to low. ?

 

[NLMGSAN]

I had sudden braking in the spring this year, but that had nothing to do with the emergency braking system. When disabled it still happened. Turned out it was ACC. It disappeared after an intermediate update.
But now it's back. Yesterday I was passing a large white truck on a the highway. ACC on 100 km/h. Nicely in the middle of the lane, no signals from LKA. When I almost reached the rear of the truck in the lane next to me, it slammed the brakes and reduced speed from 100km/h to 75 km/h. I pushed the throttle to stop it but when I released throttle again it again slammed the brakes.
This is happening more often lately. But never like this...