ACC Failure

[jrsAudiA6]

About 2 weeks ago my ACC/Brake guard quit working. A message to the instrument panel indicated the ACC/Brake Guard was unavailable. I have had this happen in the past but it was resettable every time except this time.

VAG COM scan found a fault in the Dist. Reg. module 13. When I checked the nature of the fault all it indicated was an internal error. Tried removing and reconnecting the connector to the sensor but there was no change. I came to the conclusion that the sensor had failed. Checked with a couple of on-line Audi parts sites to find out how much they cost and received a pretty good shock as the their reduced price was about $1800. The p/n for the failed sensor is 4G0-907-561. Did some google searches for this part and found an E-Bay seller selling the sensor with a slightly different p/n of 4G0-909-561-A. Purchased that part hoping it was functional and the dealer could get it to work with my A6. Well, the dealer is unable to code this part. As far as they are concerned the reason is the sensor is the wrong p/n. So, I'm looking to see if anyone has any knowledge about coding these sensors and if so how to do it. The used sensors does appear to be functional.

Any ideas is much appreciated otherwise I need to purchase a new one.

[2wookies]

Man that sucks! I have no help on this matter but good luck and please post what happens.

G/L

[elptxjc]

With electronic components, especially without any warranty (typically the case), I'd only buy new. Hope you don't have to learn that lesson the hard way. My only question is if you're absolutely sure that's the culprit. If yes, and you really want that feature, bite the bullet and buy the correct part new. And since you might not be able to return it if bought separately, I'd let dealer sort it out to at least make sure it works as intended. Finally, out of curiosity, did it fail without reason, or was there an accident or something else involved? And miles on the car total and since purchased? A little history would be welcome, to judge if it's a quality issue or something else. Good luck.

[Frenetic]

You try cleaning the sensor lens? I mean I know it’s obviously simple, but I had the same error pop up on me and, while I didn’t scan my car at the time for codes, I cleaned off some residual wax I must have got on it and the error promptly vanished.

It wouldn’t surprise me if that module was the log for a simple sensor block error and maybe nothing to do with the actual module itself.

[jrsAudiA6]

It failed on it's own no help required, lol. I have about 88K miles on the car. I keep the sensors as clean as I keep the car, well aware of dirty sensor issue.

[E-tron]

Hi, i have exactly the same issue. Deler quoted me 2600 euro for the failed sensor 4G0-907-541. So i ordered two new sensors from eBay with 4G0-907-561B and 4G0-907-541B. The Reason for ordering two sensors is because the sensor ending with number 561 is the master and the sensor with number 541 is the slave. I Hope this work with the dealer coding.

The new sensors is exactly the same number AS original but with the letter B in the end.

If the dealer coding works i May have a spare sensor with number 4G0-907-561 that May work on your car?

Best regards

[Soft]

FYI
Someone had the same issue, was just some corroded connectors, took it apart cleaned, and good to go.

[RAF_S7]

There is a reason the radar modules have locking screws and paint seals on the screws. It’s to deter removal.

Unfortunately (though for the right reason) you have removed your original one. This means any replacement sensor, new or used, has to be fully calibrated and usually only by the dealer. Not had it done myself, but others have. It’s $$$...

The radar sensors are considered safety critical since the operate not only ACC but brake guard. Any misalignment can be disastrous.

I do worry whether your dealer knows his stuff though, or is giving you a load of BS in order to open your wallet. The suffix letter on the end of an otherwise identical part number usually indicates a revision release. I don’t know if the radar sensors have to operate in a matched pair.

Good luck!

[jrsAudiA6]

Hi, i have exactly the same issue. Deler quoted me 2600 euro for the failed sensor 4G0-907-541. So i ordered two new sensors from eBay with 4G0-907-561B and 4G0-907-541B. The Reason for ordering two sensors is because the sensor ending with number 561 is the master and the sensor with number 541 is the slave. I Hope this work with the dealer coding.

The new sensors is exactly the same number AS original but with the letter B in the end.

If the dealer coding works i May have a spare sensor with number 4G0-907-561 that May work on your car?

Best regards

Please keep me informed as to the outcome of your situation. If what you did is successful than I may take that good (561) sensor off your hands.

[GilliamOS]

The PN 561-A is for cars with a build date after 07-11-2011, yours must have been built before that. Note the message about confirming PN with ODIS/VCDS.

https://i.imgur.com/T72N8DX.png

[E-tron]

I have tried to clean the defective sensor 4G0907541, when i opened the sensor it was filled with salt from our bad climate in Norway. It looked like the seal on top of the sensor gave up. Cleaned everything up and still no contact. So i ordered two new sensors from ebay.

[E-tron]

Please keep me informed as to the outcome of your situation. If what you did is successful than I may take that good (561) sensor off your hands.

I will keep you informed, when i was at the dealership last time the sensor 4G0907561 was ok. Maybe i can ask them check it once again to confirm it is still alive.

[E-tron]

The PN 561-A is for cars with a build date after 07-11-2011, yours must have been built before that. Note the message about confirming PN with ODIS/VCDS.

https://i.imgur.com/T72N8DX.png

I would like to know what the letter B in the end would represant?

[E-tron]

There is a reason the radar modules have locking screws and paint seals on the screws. It’s to deter removal.

Unfortunately (though for the right reason) you have removed your original one. This means any replacement sensor, new or used, has to be fully calibrated and usually only by the dealer. Not had it done myself, but others have. It’s $$$...

The radar sensors are considered safety critical since the operate not only ACC but brake guard. Any misalignment can be disastrous.

I do worry whether your dealer knows his stuff though, or is giving you a load of BS in order to open your wallet. The suffix letter on the end of an otherwise identical part number usually indicates a revision release. I don’t know if the radar sensors have to operate in a matched pair.

Good luck!

Thank for your good advice:) the Main difference was the backing plate (the one you screw in to the bumper) in the back of the sensor. So i swapped the backing plates from the old sensor so it fitted perfectly.

I Hope the dealership can make it work.
They will fully calibrate the acc sensors Also👍

[Soft]

Following, please share the dealer cost for aligning and coding, I might need the same :-(
Strange thing is that it seems to be failing after the car has been into a garage with 20c +,
and works again when the car has coole down to outside/winter weather.

[GilliamOS]

I would like to know what the letter B in the end would represant?

C7.5, model year 2015 to current.

[E-tron]

C7.5, model year 2015 to current.

Thank you sir:) facelift model.

[E-tron]

Got the car back from the dealership. They calibrated the ACC sensors and tried to code them with the original sensor codes without success. But they aligned the sensors. So no i Will tri to code them with vag-com so i think it is still possible to get them working but only time Will show. Anyone Else with experience ? After all they retrofit acc to cars without acc. Maybe i Will try to code them like the facelift A7/A6??

[E-tron]

The aligment of the acc was about 460 us dollars but that included coding and removal of component protection.

[Soft]

The aligment of the acc was about 460 us dollars but that included coding and removal of component protection.

So 3600.- NOK then.
Do you have a list of items they did, would be worth to check the cost in Sweden.
Had to replace the clutch pack on mine, was close to half price in Sweden

[E-tron]

So 3600.- NOK then.
Do you have a list of items they did, would be worth to check the cost in Sweden.
Had to replace the clutch pack on mine, was close to half price in Sweden

3900NOK for realigment of the acc and coding.

[jrsAudiA6]

Got the car back from the dealership. They calibrated the ACC sensors and tried to code them with the original sensor codes without success. But they aligned the sensors. So no i Will tri to code them with vag-com so i think it is still possible to get them working but only time Will show. Anyone Else with experience ? After all they retrofit acc to cars without acc. Maybe i Will try to code them like the facelift A7/A6??

Do you have an understanding what it takes to code these devices?

[E-tron]

No i dont have any experience yet. But hope to learn from some vag-com guys? Maybe somobody can give med some help?

[Soft]

To make it clear, they did remove the protection,
They did align
They did not re-code them to work with your controller/car,
and, did not understand why it didn't work?

[E-tron]

Hi, they got rid of the component protection and manually tried to code them with the codes that came originally with my car through elsawin. The coding was okay but the fault code remains: computer unit unvalid. I think it is beacuse the acc lever unit on the steering column is pre facelift with another part number then the facelifted versions of A7/A6. So maybe if i get hold of the facelifted acc steering column lever it May work? I would like to no the coding om ACC sensors from another facelift owner og the A7/A6 with the following specs: acc, lane assist, blindspot, front and rear view camara, air suspension, tow hook and adaptive xenon plus headlights. Anyone willing to svare?

Best regards

[Soft]

Seems plausible
but, I have been looking into changing the stalk to lane assist,
and it doesn't seem to be any hw/sw issues using post FL for this.
Could Audi not confirm what the problem was?

[E-tron]

No, the retrofits day is over at my Audi dealership. Before they did all sort of things, but they have much stricter policy now with the new chief. But i know for sure that vag-com has more oppurtunities for coding. So maybe i can use the radars if they Are coded correct with pre facelift steering column? Anyone can explaine??

[Sr94uk]

No, the retrofits day is over at my Audi dealership. Before they did all sort of things, but they have much stricter policy now with the new chief. But i know for sure that vag-com has more oppurtunities for coding. So maybe i can use the radars if they Are coded correct with pre facelift steering column? Anyone can explaine??

I know this is 5 years on.. I'm in the same position, I have Internal Electronic Failure showing on my front right sensor (4G0 907 561)..

I can't find another sensor in the UK which doesn't have either the letter A or B at the end.

Did you manage to get the part number ending in B to work?

Please reply if you can!

[karlito]

Is there a way to code out the message about acc and brake guard unavailable? I have the same issue but I dont care nor use ACC.

[bonafyd]

Is there a way to code out the message about acc and brake guard unavailable? I have the same issue but I dont care nor use ACC.

Thank me later[up]
https://www.youtube.com/watch?v=AgkjK_awk1Q&list=PLqc-kiqcimdt3Mqua_Bn92VVW-3sWGLb6&index=3&ab_channel=M.ADiagnostics

[widebodyfx]

Would be cool if that worked cause it's one of the reasons I don't want to change bumpers on the TDI knowing the recalibration is a pain in the ass.

[karlito]

I wanted to bring this thread back to life to see if anyone has figured this out. I tried the instructions in the video above but it does not apply to my vehicle.