ACC sensor faults

[k_rider]

Just took my 2016 Mk3 Octavia into the dealer today for what I thought was to be warranty repair on an ACC (adaptive cruise control) sensor problem. The fault is a warning on the MFD telling me 'Front assist/ACC no sensor view' and cruise control control being inoperative. This mostly happens when changing lanes after following another vehicle for a time (basically, when the vehicle in front 'disappears' from the sensor's view).

I haven't had time yet to check the fault codes via VCDS, but fault codes were found by the dealer at the last service a couple of weeks ago - hence today's visit.

At the end of today's session I was hit with a $460 bill for aligning the sensor and the rear axle (RS wagon). Not only was I staggered by the cost, but also by the fact the car is only 2 years old with less than 20k km up and needing such an alignment already. I mostly drive urban, with an occasional run up the M1 and very occasional NSW rural roads. One of the 'explanations' given was that driving on rough roads could cause the sensor mis-alignment! Really!?? If that's the case, that suggests some pretty poor design.

There is also a hidden sting here, in that when I asked about the implication of having a wheel alignment done at the local, friendly tyre shop, I was told that the sensor may need to be re-aligned as well...

But... driving home from the dealer tonight, after turning a corner behind another car, the warning popped up again! Looks like I'll be talking to the dealer again tomorrow!

So, I was just wondering if anyone else in the group have had similar problems with the ACC sensor, or is my experience a bit of an isolated incident?

[ope126]

I would have put my wallet back in my back pocket!!!
Contact Skoda / VAG...they will sort this out!

[kamold]

Acc radar alignment with the current gen radars takes about 5mins, just needs to be 1.5m from a wall.
Ideally it requires a road test afterwards (active calibration) however this isn't required to clear the fault.
The module itself is faulty and needs to be replaced. I've seen this before. You can run the alignment successfully, and the radar seems OK, then after a few minutes in traffic it faults again.
As above I'd want to be fully reimbursed for any cost you've incurred. Warranty job for sure.

[k_rider]

Yeah, kicking myself a bit for coughing up...

I am certainly going to insist on the cost being reimbursed if the sensor is faulty. Car goes back next Tuesday.

Thanks all for your responses.

[Tigger]

Warranty should cover that!
Skodas have a 5 year unlimited KM warranty now -so there is NO WAY you should have been made to pay for that!

[k_rider]

Yes, I believed it should have been covered by warranty as well. I stumped up the cost at the time as it would likely have been a stalemate resulting in them doing nothing. I was intending to contact Skoda Australia to review the situation afterwards anyway.

Anyway, as it turns out, the saga continues...

I took the car back last Tuesday where they had another crack at re-aligning the sensor. After doing that, the car was taken out for a test drive and fortunately, the error popped up for them this time. After that, they consulted with Skoda tech support and it was determined that the front rego plate was positioned 'too low' - the lower edge of it potentially causing reflections back to the sensor. To confirm this theory, the car was taken for another test drive with the front rego plate removed. Apparently the fault didn't show up, so it was considered that the solution was found. At that, the front rego plate was re-fitted slightly higher. After I reminded them that the fault was now clearly not due to 'sensor misalignment', it was agreed that the amount they charged me originally, would be refunded. Cool, so that was that I thought...

Problem is, I didn't get more than 400m from the dealer's when the error message popped up again. So, the problem is still there - great! Back to the dealer again sometime this week/next week.

Stay tuned!

[dArK5HaD0w]

that's bl00dy annoying!!
thought ur problem was resolved by repositioning the numberplate higher!

has there been anything done to ur steering wheel? reading on the briskoda forums, i spotted this bit.....

"The sensors do go out of alignment, a number of factors can influence this. Sometimes the car will think the sensor is out of alignment when its no because all ACC faults must be cleared by re-running the basic settings.

Removing the steering wheel and disturbing the slip ring is one such case, having a wheel alignment done by someone who does not know what they are doing is another, very common problem on the Audi forums.

Obstruction of the sensor is another.

If the steering wheel is removed for whatever reason, the the whole ACC needs recalibrating anyway because of the slip ring issue. The reason it stops working is for safety, it no longer has the reference points it was aware of so pops up the alignment error. The ACC system has very tight tolerances, its to stop you running into the back of a car and as soon as the system thinks the smallest of things is wrong it will throw an alignment fault.

Using VCDS you can clear the alignment fault, but it will return straight away unless you run the full basic settings and reset the alignment angle. I did this on my Audi which has ACC after replacing the front grill to remove an alignment error, its been fine ever since and nothing has been touched.

Edit: You can try simply clearing the misalignment angle with VCDS from the cruise control module, it will then attempt to relearn the correct values from scratch. To reset misalignment angle go to – Basic settings - 3. Reset misalignment angle, the alignment error will return after about 30 miles it cannot get values in tolerance. The article linked to below shows how to calibrate an Audi using VAS, you cannot use the latest VCDS because it no longer supports full ACC Calibration for safety reasons.
Audi4Ever - a4e Blog - Detail - ethmb - ACC Calibration / Adaptive Cruise Control / A4 A5 Q5 / Distronic"

[k_rider]

Heh, yeah... So did the dealer service advisor!

Steering wheel hasn't been touched and being slack, I haven't had a wheel alignment done since buying the car.

The first thing that was done when I took the car in originally was an alignment of the rear wheels only - makes sense I suppose, because if that's out, the car would tend to track down the road at an angle. The service advisor did point out the need for the specific requirements with performing wheel alignments on ACC equipped cars.

After the rear wheel alignment, the sensor was re-aligned - I was not told if it was considered to actually be out of alignment in the first place.

So, the system has been aligned, twice, and the sensor's 'view' has been cleared. Presumably the next step is component replacement...

Having a background in electronics and systems engineering, I know full well the frustration of intermittent faults!

[HPRS230]

Re "The service advisor did point out the need for the specific requirements with performing wheel alignments on ACC equipped cars."

I get a Wheel alignment every 6 months, and I rang 3 Skoda workshops and they all said no re-calibration is needed, the car knows if its in spec or not.
So interested to hear more about a Re-Cal at every wheel alignment, I might ring my Skoda workshop and ask again, its due soon.

[k_rider]

Well, after about 6 weeks, it looks like the ACC problem has been resolved!
The car finally went back to the dealer two weeks ago and kept by them until last Friday. After multiple alignments, adjustments, test drives and no positive results, the ACC sensor ended up being replaced mid last week.
So far the problem hasn't recurred...
The original $462 bill I was given will also be reimbursed. So, I'm pretty happy with the overall outcome!
The 'upside' was that I got to drive a couple of contrasting loan vehicles - an Audi Q7 and a Skoda Rapid! The Rapid was fun, the Q7 was nice, but just way too big and cumbersome.