Audi pre sense and ACC

[Gig80]

I guys just a quick question for anyone with pre sense and ACC.
Over last couple of days I have had a couple of issues
1) ACC on motorway near exit slip road it didn’t pick up a stationary wagon ( was actually accelerating) resulting in me stepping on the brakes firmly
2) had a message earlier in the day saying pre sense limited thinking it’s a build up of road dirt as happened during the snow/frost. Anyway was stood at a jnc then accelerated to follow car turning in from other direction, and bam car slams to a hault, I thought I’d been hit and then see my pre sense had kicked in.

A) this warrant a visit to the dealer
B) thoughts on pre sense, potential hazard in the making ?
C) anyone had senor issues? ( had the sq5 pick up objects/signs when going round tight corner but never intrusive)

Thanks in advance

[PieterZ]

Has the bumper been off? If so acc will need recalibrating.
At what setting is it, early or late?
If the 2 sensors are fully covered in snow it will probably not work. Had the same experience on my previous car. With the RS I haven’t had enough snow to trigger it.

[J88NOG]

I find it will have a panic if a car is pulling into a filter lane to cross the motorway (and so technically undertaking it as it decelerates). I've had an instance where it has jammed on the brakes whilst over taking an HGV in rain.

Other wise I find the system very good. I had more of those problems in my previous Golf R with ACC, which seemed to be very sensitive.

[s4tokyo]

On a separate note, I was in 'city' traffic this evening and stopped at traffic lights. Suddenly, 3 separate times in space of about 20 seconds, the belts grabbed tight (with throttling tension actuator noise) and the hazards coming on. The car in front of me was maybe 1 1/2 ~2 m away. A bit startling for first time experience - once was enough but 3 times in succession?!:)

It seems that car behind me drove up too close, that's all I could think of. But what's the setting limit so, ...because that can happen all the time in a city.
Pre sense is set at 'late' (activation), so not sure what I can do to prevent re-occurring other than switching OFF.

Anyone on Forum have similar experience? .......... OR might I be looking at a sensor defect?

[RS4John]

Yeah - that's Pre-sense waking up I think - I've had it do that...get complaints from the passenger seat to like it's my fault...

[Gig80]

Hi guys,

Thanks for the responses, going to have a chat with the dealer tomorrow to look at the sensors.

I’ll let you know if they say anything, however I fear that I will just have to get used of these oddities of the new tech

[RS Owner]

however I fear that I will just have to get used of these oddities of the new tech

or you could disable it (at least I think pre sense can be disabled in the car menus?)

I have had the warning flash up in the instrument panel but nothing more. I would freak out if the car was to actually brake to halt when I didn't want to.
Also I understand pre sense doesn't operate above 50 mph (85 kph) so maybe that's why I haven't experienced it much.

[Gig80]

Ha ha I guess I need to put my foot down a bit more then

[Graeme4130]

I guys just a quick question for anyone with pre sense and ACC.
Over last couple of days I have had a couple of issues
1) ACC on motorway near exit slip road it didn’t pick up a stationary wagon ( was actually accelerating) resulting in me stepping on the brakes firmly
2) had a message earlier in the day saying pre sense limited thinking it’s a build up of road dirt as happened during the snow/frost. Anyway was stood at a jnc then accelerated to follow car turning in from other direction, and bam car slams to a hault, I thought I’d been hit and then see my pre sense had kicked in.

A) this warrant a visit to the dealer
B) thoughts on pre sense, potential hazard in the making ?
C) anyone had senor issues? ( had the sq5 pick up objects/signs when going round tight corner but never intrusive)

Thanks in advance

I had the presence kick in a few times for no apparent reason on my last B8. It was never a dangerous situation (ie always at low speeds), but I'd be driving through a supermarket carpark, for example, and it'd just jam the brakes on for no reason at all. It did my head in to be honest as I was never sure it wasn't going to do it on the motorway at 90 and cause a crash. I spoke with the dealer, who said they couldn't see any issues
In my B9, it's only kicked in once in 11 months, and it was because someone pulled out in front of me