Ok, I’ve got a wierd issue with my ACC. The front bumper came off to replace the headlights (constantly fogging up badly tried for a couple of years to fix but couldn’t, so just got new ones!)

Anyway, lights all good but the ACC now only works sometimes at low speeds but not always, simply doesn’t activate & shows the error message ‘Audi Braking guard & ACC unavailable: No Sensor Vision’.

if it does switch on it works fine until I hit motorway speeds when it just switches itself off, displays that message & doesn’t come one again. If I don’t use it 7ntil I hit the motirway & up to speed, it just doesn’t do anything except display the same message

no errors showing! Plugs & Wiring checked, all coding checked, nothing erroneous found. 
Now tearing hair out! 

anyone got any ideas?

Is the ACC sensor in the front bumper? If so, maybe it was disturbed or damaged during bumper removal.

That’s was the 1st thought but the connections were reported good (I haven’t checked them myself) & the sensors weren’t removed from the bumper. There’s also no error codes recorded by the car.

Im concerned that if I pay for a calibration, it may not flag up whatever’s causing this if it isn’t just a calibration error. (The final phrase in the error message is the most confusing, ‘No sensor vision’. )

That central camera above the mirror,  I thought, was only for the lane keeping assistance, which does work consistently. No other systems appear to be affected.

ive been out to the car today & the ACC system switches on with no error messages on the drive  but I Haven’t driven it. 

it’s the fact that it sometimes works, but only at slow speeds (urban, 30-40), as soon as I’m up to motorway speeds, it switches off & shows the error message & simply will not come back on even if I stop for a break. It’s being a bit elusive & inconsistent! 
not sure what the next step is now!

I’ve seen one video that showed some corrosion on the connector block for the sensors which caused a problem but, that also flagged as an error code, which mine isn’t! 
 

im going to ask a non-franchised Audi specialist tomorrow if he can help, but he’s not an electrics specialist, with anything mechanical, he’s damn good. But I’m going to have a look at the sensors & connectors asap, weather dependant! Just to provide ev they connections are good.

 

Cars booked in with a non-franchised specialist for a ACC calibration next Thurs.