Well had fun and games going to Birmingham yesterday in drizzle and rain , cruising at 70 on ACC car flashes red "BRAKE" warning and error of impaired front assist appears , OK couple of miles later it goes , in a 100mile trip it alarmed 11 times. I realise in the manual there are references to extreme conditions of snow and ice impairing the system but a bit of spray on the M6?

 

I also get the system impaired error every time i go up  with the dog to Beacon Fell which is a small forestry location , and park my car ( on tarmac) in parking area which is edged with 2ft high grass, the car does not touch the grass at all. After an hour or so I leave I immediately get the alarm which stays until i am half way home.

I have had the system checked by SKODA and told there are no problems. Looking on other VW forums it appears this system is very prone to these errors. 

Any advise on whether it is worth pursuing a "repair"

Have you tried adjusting the sensitivity?

 

Ours used to get easily confused, but we dialled down the sensitivity in the infotainment system and it's largely been fine ever since...

 

 

Edited 29 July, 20196 yr by silver1011

Its not the fact that the front assist alarm is too sensitive , its the fact that the system turns off with the error "front assist system impaired" which means my ACC stops working . I could be ok with it not working in extreme weather conditions but spray on the motorway is pretty common in uk.

Think about it.  What would you expect the system to do?

 

It has shut itself down, for safety, and warned you that it has done so, so you'll do the distance adjustment yourself.

 

If it were to stay on, it would need to be clever enough to distinguish between the radar reflections from the spray droplets and those from the back of the car in front, so that it knows which to follow.  It would also need to able to work out, from just the radar reflections that it's receiving, quite how much more slippery than normal the road surface now is, and be able to make the appropriate adjustment to the distance between you and the car in front.  

 

That's asking an awful lot, and I reckon that a "safety shutdown" is the right thing to do.  You'll then do your bit, and arrive safely home (rather than be placed automatically behind the car in front, and aquaplane nicely into it when it suddenly stops).

3 hours ago, StuartAK said:

Its not the fact that the front assist alarm is too sensitive , its the fact that the system turns off with the error "front assist system impaired" which means my ACC stops working . I could be ok with it not working in extreme weather conditions but spray on the motorway is pretty common in uk.

 

I would say there is something wrong with it. In our 15 months of ownership it’s displayed that error three times - two times whilst driving through a narrow tunnel, and the third when the sensor was covered in dead bugs. We did about 8 hours of motorway driving through torrential rain this weekend and it worked perfectly throughout. 

 

It’s had the very occasional false alarm, but so occasional that I’ve not needed to change it from whatever sensitivity it came set to at delivery. 

Had mine for 2 years and 20,000 miles and it's only ever failed like that in wet snow. Definitely something wrong with the OP's car that needs sorted.

On 29/07/2019 at 17:36, MrTrilby said:

 

I would say there is something wrong with it. In our 15 months of ownership it’s displayed that error three times 

 

Make that 4 times. Started the car today and it flashed up “sensor impaired” and we have no front assist or ACC. And this time it doesn’t seem to be clearing itself. Perfect timing for our holiday on Monday with lots of driving required. 😡

Mist, heavy rain or snow all seem to upset the sensor. The default setting is also too sensitive, since using the medium setting I’ve had a lot less false warnings.

False warnings are not the same as "sensor impaired" which indicates its not working at all , altering the distance at which it alarms will not stop the "impaired" error , you just wont get as many warnings. Looking at other forums for VW's etc its a pretty common problem , which I guess I will have to put up with

On 17/08/2019 at 20:15, MrTrilby said:

 

Make that 4 times. Started the car today and it flashed up “sensor impaired” and we have no front assist or ACC. And this time it doesn’t seem to be clearing itself. Perfect timing for our holiday on Monday with lots of driving required. 😡

 

Fortunately, leaving it 24hrs, then switching front assist off and back on again seems to have “fixed” it. I had just pressure washed the car, and we had torrential rain not long after. I suspect the radar sensor housing is not terribly well sealed as it was still dribbling water that evening. I’m wondering if the fault was caused by water inside the housing. 

where is the radar housing I have looked around the front from underneath and cant see anything.

I get front assists impaired warning if I park near to long wet grass, it usually "resets itself" after about a mile driving home.

Answered my own question I assume the green thing is the radar gizmo

Yep it’s the big green unit under the badge in your photo