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Need help on safety feature Collision Prevention Assist Plus

AlanA

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#1
I'm a first-time Mercedes Benz owner and new to your club. Hope somebody could give me more info on CPA+.

I just got a pre-owned GLA250 last week - just 5K odometer reading so relatively new - and was very excited about it that I went on a road trip with my wife over the Thanksgiving Holiday here in Canada.
On our way home, I was travelling around 100 Kph when my cell phone fell from the dash. When I looked down to pick it up, my wife screamed 'brake!' I forgot about the car in front of me - I know bad driving... Luckily I was able to stop with only about a couple of feet to spare!

Problem is I didn't get any visual or audible warning from my GLA. The manual said a red warning icon should appear followed by an audible beep if CPA+ senses
an impending collision. I didn't get any of that. I'm pretty sure that CPA+ was enabled since I checked it before I left. Also, assistance graphic did not show any icon
indicating any of my installed safety features - attention assist, blind spot assist etc. - were off or disabled.

The next morning, I went to my dealer and told them what happened. The sales person I talked to did not seem to know much about how CPA+ works. He actually
told me that for CPA+ to work, the other car has to be running along side my car!?? How can that be when from what I understand the entire purpose of CPA+ is
to prevent and/or minimize damage resulting from rear-end collisions? Another sales person told me that CPA+ does not work all the time!!? This makes me question the
reliability of this feature.

Service wasn't much help either. They said there were no error messages in the onboard computer - meaning everything is ok - so they can't bring it in for service.
They said I have to wait for my service schedule before they can check out my complaint. Problem is I just got my GLA so service is more like a year away.

I have a GLA 250 without distance warning. My sales person told me that CPA+ is standard and that it will work regardless of whether I have distronic or not.
Is this correct? If so, why didn't I get visual and audible warnings when I needed it most? How is CPA+ supposed to work? Is there something I need to do first, some setting I'm missing?
Does anybody have a similar issue or experience?
 
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#2
Welcome! The Collision Prevention Assist Plus works up to 105 kph, are you sure you weren't going faster than 100 kph?

For Collision Prevention Assist Plus to work you have to travel 20mph hour or more, having cars drive next to you makes no difference.
 
OP
A

AlanA

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Thread Starter #3
Hi GLAMike.

Thanks for the response. I'm almost certain that I was travelling at the speed limit as I make it a point not to speed. Besides, there was a bit of a drizzle that night and a lot of cars were on the highway going home to Toronto
from Niagara. Of course its possible I may be travelling over 105kph as I wasn't really paying attention. Thanks for this bit of info, thoug.

But setting aside the speed question, the DriveAssist menu in my GLA does not have an option for Distance Warning. It has the following options:
Assistance Graphic, Attention Assist, Collision Prevention Assist Plus, Blind Spot Assist and ESP.

I noticed that this menu was the first thing the service rep looked at when I went to my dealer the next morning. He seemed surprised that there was no 'Distance Warning' option there.
Also, the manual shows 'Distance Warning' as an option. My question now is - is the 'Distance Warning' option replaced with the 'Collision Prevention Assist Plus' option in the GLA? Or should both
options be available - and separately configurable?

Also, Assistance Graphics shows only an image of half my car and 2 white lines shaded black or gray in between the lines. There is no small car icon at the end of the lines like what the manual shows.
In fact I've never said that Assistance Graphic change even when I am approaching a vehicle in front. Is this because of my missing 'Distance Warning' option?

I should also mention that the CPA+ red triangle icon comes up BRIEFLY every time I start the car. Also disabling CPA+ shows the CPA+ disabled icon in Assistance Graphic. Other than these, there
really is no indication that it works specially in light of my experience that night.

Could these just be a software problem or update?
 
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#4
Hi AlanA there are two different options, one is the COLLISION PREVENTION ASSIST PLUS the other is the Driver Assistance Package with DISTRONIC PLUS that applies the brakes for you. There's also the PARKTRONIC with Active Parking Assist which will have the alert sensors and self parking. The GLA only comes standard with COLLISION PREVENTION ASSIST PLUS

This is the disclaimer for COLLISION PREVENTION ASSIST PLUS
COLLISION PREVENTION ASSIST may not be sufficient to avoid an accident. It does not react to certain stationary objects, nor recognize or predict the curvature and/or lane layout of the road or every movement of vehicles ahead. It is the driver's responsibility at all times to be attentive to traffic and road conditions, and to provide the steering, braking and other driving inputs necessary to retain control of the vehicle. Drivers are cautioned not to wait for the system's alerts before braking, as that may not afford sufficient time and distance to brake safely. Autonomous braking operates at speeds up to approximately 65 mph. Braking effectiveness also depends on proper brake maintenance, and tire and road conditions.
 

hotGLA

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#5
Collision Prevention Assist Plus doesn't brake for you, only if you get the distronic option.
 


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