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Discussion Starter · #1 ·
Hi

Over the past couple of days I've done a couple of 200 mile journeys in my 3 week old T-Cross

On both journeys, I've had a "Front Assist Unavailable. Sensor Impaired" and "ACC Unavailable. Sensor Impaired" warning followed by a yellow warning symbol on the instrument display. On the first occasion the error occurred after about 2 hours and lasted for an hour before correcting itself and working OK for the remainder of the journey. Today the error appeared after 3 hours and lasted for the remaining 90 minutes (it did briefly resolve for about 2 minutes before reappearing). Bizarrely as i got home the front parking sensors worked perfectly in the car park, which I assumed wouldn't activate given the yellow warning symbol was still on (tho I guess this may use different sensors to Front Assist & ACC).

Before I start contacting my dealer to have it checked it out, has anyone else experienced this and does anyone have any solutions to resolve ? Obviously on a motorway it was impossible to try turning the engine on and off again to see if that cleared it.

Thanks in advance

N
 

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I think this type of problem has been discussed on here before. In bad weather, heavy rain etc, the sensors can't operate properly and so switch off... Was this the case with your journeys., bad weather..? It seems to be a sort of fail safe, if the sensors can't see properly, it's better to have no signal than a false one.
 

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Discussion Starter · #4 ·
Thanks, sounds similar to the other forum topic you've mentioned and also seems to be an issue on the T-Roc and Golf which use the same system judging by posts on those fora.

Having said that it was by no means bad weather today - it was just heavy drizzle and mist (not really rain) when it went AWOL, though it had been operating normally under identical weather conditions for the previous hour or so. Yesterday it had been heavy rain just before when it failed. Does seem to be a flaw / feature / failsafe in the VW design from reading round online - always disconcerting when you get a big exclamation mark icon in the middle of the display !.

I'd assumed that if the Adaptive bit of the cruise control couldn't work it would revert to "normal" cruise control where it holds the speed at what you set it (which was all my previous Vauxhall had) whereas the cruise control just stopped working entirely which was a bit of a pain in the a**e. I'll see how it holds up over the next few weeks and mention it to the dealer anyway.
 

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Fyi, the ACC distance sensor is a radar device behind the front VW badge. Parking sensors are the small circles around the front and sides of the bumpers.

The radar sensor can be a problem in very heavy rain, not just VW but other marks have reported this too. The usual advice is to first clean the badge so there's nothing on it interfering with the signal.
 

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Discussion Starter · #6 ·
Cheers. Will try and remember to wipe down the badge after each break en route the next time.

Do you know if there is any way of just having basic cruise control (set a speed and the driver has to adjust for other traffic etc) or is it adaptive or nothing ? The dealer showed me at handover how to adjust the gap distance using the ACC and vaguely mentioned something about being able to have it on but with no distance measuring but the manual doesn't mention this.

Other than that all is good with the car so far and quite impressed with the fuel consumption which it seems to be showing
 

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No, there is no 'basic' cruise control available, unfortunately.

-eelis-
 

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No basic cruise control, but our T Cross does have a Speed limiter option. You can set a max speed and the car will not exceed it, so if you want to travel at 100kmh along the highway you can set the limiter to 100, keep your foot on the accelerator and it will max at 100, slowing down when you lift your foot, and none of the ACC functions will be operating (its Limiter OR ACC, you can't run both at the same time.)
 

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Discussion Starter · #9 ·
Eelis said:
No, there is no 'basic' cruise control available, unfortunately.

-eelis-
Thanks. Happened again today in a snow flurry which I gather is a trigger for it (stayed operational in earlier rain). It's a pity that it isn't programmed to maintain the set speed for, say, 10 seconds once it picks up the sensor impairment as one second you're trundling along at 60mph then all of a sudden with no warning there's a total loss of power until you realise what's happening and can put your foot back on the gas.

Now that I know what it is I'm sort of prepared but will still mention it to my dealer to see if there are any tweaks available
 

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Discussion Starter · #10 ·
glint.bladesong said:
No basic cruise control, but our T Cross does have a Speed limiter option. You can set a max speed and the car will not exceed it, so if you want to travel at 100kmh along the highway you can set the limiter to 100, keep your foot on the accelerator and it will max at 100, slowing down when you lift your foot, and none of the ACC functions will be operating (its Limiter OR ACC, you can't run both at the same time.)
Thanks for that. Yes mine has a speed limiter too but I guess what I'm looking for is the reverse of the limiter so that the car will maintain its speed without needing to have a foot on the gas if the ACC sensors fail
 

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[/quote]

Thanks. Happened again today in a snow flurry which I gather is a trigger for it (stayed operational in earlier rain).
[/quote]

Yes, snow is poison for it, I should know. ;)
I read somewhere, that those radars or the logos where the radar lye under, were heated before, to prevent that to happen.

-eelis-
 

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Discussion Starter · #12 ·
Yeah that would be useful. Yesterday morning it was very cold (but dry) and the car had been parked outside overnight at my Mum's rather than in its usual place and had quite a coat of frost on it, but despite wiping the VW badge down before setting off the ACC sensors didn't operate for the first hour or so then cleared themselves en route and stayed operational for the remaining 3 hours of the journey.

If there was a fail-back of basic cruise control if the radar couldn't detect properly it would be far more sensible (and safer). I know having to use the accelerator rather than relying on cruise control is a bit of a First World problem but it's one of those things that once you're used to having it, its weird not having it
 
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