TeAmEr

Hi All,
I have an Audi A6 2.8FSI quattro 2011 with 75k km on it.
Was driving normally about 40-50 km/h and i was the only one in the street (good luck) its sunny and dry road.
Suddenly the car applied full breaks for half a second, scared the **** out of me, a message appeared on the dashboard and disappeared, i couldn't catch it but there was something about "break pedal" ... couldn't read the rest because it was gone, then the car drove normally.
I was driving from home to a repair shop to fix the wheel (there's a nail in it) the moment i was driving all the wheels had the optimum tire pressure (checked and added air before leaving home).

I am glad this didn't happen at higher speeds on the autobahn (usually drive between 180-240 km/h).
Anyone had this issue before? or might know what is the reason?

Also the car was parked for 2 years. i changed the gearbox oil (basically i lost the gearbox oil while driving one day) and the engine oil (right when i purchased it) should i have flushed the break fluid as well ? might that be a reason? (this is the first time it does that since i purchased it 2000km ago)

KevinGary

superswiss

That would be the brake guard feature, which if it detects that you are on collision course with another vehicle will automatically apply the brakes at the last moment to either completely avoid the collision or at least slow the car down to a speed that minimizes casualties. Occasionally, the system has a false positive and accidentally mistakes something for a moving car. You may have had airborne debris or something on the side of the road that got categorized as a moving car heading your way by the radar sensors in the front bumper. The feature can be turned off in the Driver Assistance section in the MMI, but it's generally a good idea to leave it on. The occasional false positives don't outweigh the safety net it provides.

TeAmEr

Sadly there is no collision detection / autobreak / driver assistant or whats I think called Audi sense or something. even if there were any, I was a clear day on a clear road without anything infront or behind me

DB22

DB22

superswiss

I honestly don't know why the car would brake on its own if it wasn't equipped with the Brake Guard/Audi Pre Sense. If you have adaptive cruise control, then you have brake guard. You'll have to tell us the exact spec of your car with all the options to try to make sense of this, but other than Pre Sense/Brake Guard/ACC there is no other system that would apply the brakes like that. The only other system is ESC that will apply brakes in order to stabilize the car, but that would only happen if you are about to skid off the road, not if you are driving straight, unless there is some kind of a malfunction in your car.



Certainly true, but I have yet to read of a case where that actually happened. Generally the false positives result in a brief jolt on the brakes and the system quickly realizes the error and lets go off the brakes. You can also manually override it by stepping on the throttle or if there is indeed an obstacle that you didn't deem a concern yourself then minor evasive steering input will tell the system that you are on top of it. I get very very few false positives and in generally I just let off the throttle when it happens, which then immediately makes the system back off unless there is really a car ahead of me coming to a last minute stop. Most times all I get is a false aural warning and it never actually applies the brakes.

The system is definitely an issue when I go canyon carving or on the track, but it automatically turns off if ESC is in Sport mode or off, which is what I do in those cases anyway. It's meant for daily driving and not for sporty/performance driving.

TeAmEr

I have cruise control, but not the auto stop/go one, only the older model (set/activate/disengage) where it just holds the speed even if there's a wall in front of you ( no distance selection )...
However i had a screw in the wheel, and could hear it hit the road with every wheel spin, so probably it was the ESC? does it go full breaks with the ABS working like a drill for half a second if one of the wheels slipped like 3-4 mm because of a screw?

However this didn't happen again (so far), lets wait and see..

I have an audi A6 2011 (new look) 2.8 FSI quattro with 7 speed stronic, no GPS, no phone, nothing installed on the car except cruise control and rain sensor, no cameras/radar in the grill or on the center mirror . car did 75000km only

kevrhof

My car has, rightfully, engaged the braking guard probably about 10 times since i've owned the car. Its probably had a false positive about 3 times

superswiss

No, I wouldn't expect the ESC to go nuts like that because of a screw in the tire. Most ESC allow a little bit of slip before engaging, so I wouldn't expect a screw to cause ESC to engage if all is working as designed. This is assuming that as per recommendation you use the same exact tires all around and the remaining tread is within 4/32" of each other. Quattro requires a uniform tire setup on all 4 wheels to have equal grip characteristics on all 4 corners and tread wear has to be within 4/32".