Accuracy and reliability of ACC

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Accuracy and reliability of ACC

Post by Karaduman » Wed Jul 10, 2019 1:39 pm


I have a 2019 R Line 190bhp DSG. Overall a good car. My slight issue is with the ACC. 90 to 95 percent of the time it works as advertised. However sometimes when I am coasting at 50mph (M4 Roadworks), the ACC all of a sudden does not see the car at the front and just continues at 50mph despite the car in front slowing. Very irritating despite the rarity.
Did anyone else have this problem?

Also, the gap between my car and the car in front seems fairly wide despite me setting it at the minimum setting. Or maybe I like driving to closely to the car in front.?? Not sure now.
Tiguan R Line 190 - 4Motion.
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Re: Accuracy and reliability of ACC

Post by niggly58 » Wed Jul 10, 2019 1:47 pm

Unfortunately no assistance system is 100% perfect or reliable. The VW manual points out many times that they are not a substitute for proper driver attention and control.
They must be viewed as an aid for drivers, not a substitute for.
2016 VW Tiguan Mk2 2.0L SEL 150 4Motion Manual Diesel. Indium Grey.
Vienna Black leather, electrically adjustable. 4 heated seats. Stainless exhaust trims, K&N 33-3005 air filter. RLine pedal covers. Michelin Pilot Sport 4 SUV tyres.

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Re: Accuracy and reliability of ACC

Post by Wardy » Wed Jul 10, 2019 1:54 pm

In the times you've witnessed this, was it always on the same stretch of road?

Perhaps ACC is picking up something else, rather than the car in front. Hence it's not reacting as you'd expect.
Tiguan Match 1.5TSI DSG - Urano Grey, Winter pack, 18" Kingstons, TSR, de-badged

Ordered: 18.02.19
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Re: Accuracy and reliability of ACC

Post by Essjay » Wed Jul 10, 2019 3:52 pm

If it happens on other roads as well, then I would be tempted to take it to the dealers and see if, for some reason or another the radar sensor needs recalibrating, or maybe it’s just got some dirt behind it that’s maybe affecting its accuracy.

Tiguan 2.0 TSi 180 SEL DSG 4MOTION (Sept ‘16, but MY17).
Caribbean Blue, Vienna "Storm Grey" leather with memory, Keyless and electric tailgate, Tyre Pressure Monitor (TPMS), Area View, Park Assist, Protection pack and HUD.

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Re: Accuracy and reliability of ACC

Post by hetterbr » Thu Jul 11, 2019 4:55 pm

I had issues with my ACC on my 2018 highline. I would be driving down a deserted road with the cruise on and it would suddenly produce an error and the ACC would shut down the cruise. it would show an error and then radomly the error would disapear and i could reengage the cruise. we updated the software and recalibrated the sensor. neither worked. the finally changed the sensor out and that fixed the issue.

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Re: Accuracy and reliability of ACC

Post by UnionJack » Fri Jul 12, 2019 10:11 pm

I can't speak for my Tiguan SE Nav as it doesn't have ACC, but my 2016 Golf GTD does. It failed in snow, but I cleared it off and it was fine.

The golf has been 100% reliable with it's ACC aside from that, maybe because the Golf's sensor is mounted lower so it sees more stuff. Never let me down and never had a panic emergency brake, just seems to work as advertised. I use it all the time and it always seems to behave as normal. I'd get it checked out, but beware of dealers charging for diagnostics.
The golf just seems to sit a preset time difference behind the car infront, if someone cuts in, it backs off.

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Re: Accuracy and reliability of ACC

Post by CNC » Sat Jul 13, 2019 3:41 am

I have had this happen to myself on a few rare occasions. Without warning the car will suddenly no longer see the vehicle in front and accelerate resulting in panic braking from myself to counteract it. In the 60k I have done so far probably 2-3 times, so not often but it does catch you by complete surprise when it happens, especially as I have learnt to rely on the system (I probably rely on it too much).
2018 MY SEL 150 TDI DSG 2Motion in Caribbean Blue with reversing camera & park assist plus fully debadged

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Re: Accuracy and reliability of ACC

Post by Glos Guy » Sun Jul 14, 2019 3:31 pm

I’ve had the opposite. Sudden automated breaking when there is no need, usually triggered by the collision alert system (or whatever it’s called). The first time I was on the motorway, thankfully with nothing immediately behind me, and the shadow of a bridge that I drove under triggered a brief emergency brake. The system tends to think I’m about to collide with cars from time to time, even though I have set it to the least sensitive setting. I also drive a BMW 5 Series and don’t have these problems, so whilst I agree that no system can be 100% accurate, VW technology doesn’t seem to be quite as efficient as some other manufacturers. Same with the Adaptive headlights. The VW ones are too slow to react (even set to ‘Sport’) whereas the BMW system is split second accurate.
2018 Tiguan SEL 2.0TDi 190PS 4-Motion DSG
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Re: Accuracy and reliability of ACC

Post by chillyman50 » Sun Jul 14, 2019 3:36 pm

I use ACC a lot and this just happens on occasion.

you just have to be mindful of it and quickly flip the speed down by 10mph of more to engage the breaks or manually break.
TIGUAN SEL 190PS TDI-4 MOTION, white metallic silver, DCC, Dynaudio, Voice,Leather/electric seats, Camera, Headlight wsh, sidescan, swivel towbar, added immobiliser,others

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Re: Accuracy and reliability of ACC

Post by F2paul » Sun Jul 14, 2019 7:31 pm

Use it every day , never had this kind of problem.
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