Acc,Front assist and start-stop problem

[Nuno1]

Hi all anyone ever have any problem or know of one which affects ACC,Front assist and start-stop at the same time? My ACC and front assist are coming up as unavailable and every time I start the car I get a start/stop error too on the multifunction display,I bought the car knowing start-stop wasn’t working as he offered me compensation for this and I wouldn’t have used it anyways however I didn’t realise the ACC and front assist weren’t working either, the salesman told me it was some sensor connected to the radar unit but not the radar unit itself on the front of the car which was causing the problem however Through searching online I see most people’s problems with these systems are caused and solved by a radar unit being knocked out of alignment and then re-aligned at a dealer, Has anyone had any experience with something else such as this sensor the salesman was referring to causing this error rather than the radar being out of alignment? I’d rather not go ripping the bumper off and possibly knocking the radar out of calibration if chances are it’s okay and the problem lies elsewhere with a sensor on the engine possibly, any info such as wiring diagrams and the like are much appreciated to a DIY enthusiast like myself trying to solve this annoying problem! thank you in advance!


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[Carlosfandang0]

I had this same issue when I hit a pheasant which totally knocked the front assist radar off and smashed the lower grill, I replaced the grill and re mounted the radar (with new clips as these had been broken) and cleared the faults with VCDS and all is good, as the mounting plate for the radar had not been moved it wasn’t necessary to have it calibrated, front assist and ACC both work perfectly! The best course of action for you is to scan the car for fault codes to see if there is an issue with a particular component before attempting any fix, taking the bumper off doesn’t affect the radar in any way, they are not connected, if you’ve just bought the car take it back and get them to fix it, it’s you’re right as a buyer under eu law,
Take a look at the radar and check if it’s loose/wobbling, it could just need to be popped back into its mountings.

 

[slider09]

Is your battery OK? These sorts of issues where several separate components are at fault can point to battery issues.

If the battery has been disconnected you get these error messages but they soon go once the car has been driven.


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[Nuno1]

Yea I think maybe at some point in the cars life it got abit of front end damage so maybe this knocked the sensor out of alignment and it was just replaced and not re-calibrated, I’m really hoping this isn’t the case though as I’ve heard it’s quite expensive to get these units re-calibrated here in Ireland and not many non-dealer garages have the equipment for them, I checked the battery and it looks pretty new, I’ve never had any issues starting the car or any other codes relating to a low battery yet but il keep that in mind thank you, my golf has the older style front radar sensor with a round ball shaped lense and the casing around it seems to rattle a bit but il have another look at it with an inspection mirror next time to see if anything looks broken, thanks guys!


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[Carlosfandang0]

Yea I think maybe at some point in the cars life it got abit of front end damage so maybe this knocked the sensor out of alignment and it was just replaced and not re-calibrated, I’m really hoping this isn’t the case though as I’ve heard it’s quite expensive to get these units re-calibrated here in Ireland and not many non-dealer garages have the equipment for them, I checked the battery and it looks pretty new, I’ve never had any issues starting the car or any other codes relating to a low battery yet but il keep that in mind thank you, my golf has the older style front radar sensor with a round ball shaped lense and the casing around it seems to rattle a bit but il have another look at it with an inspection mirror next time to see if anything looks broken, thanks guys!


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If it rattles a bit then it’s loose! This is likely the issue, I had to buy one of these kits
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/153406015995
as the three black plastic clips were damaged in my case which caused the radar to wobble as it was loose, the radar clips into the mount shown and then the mount clips into the black clips which mount onto the bracket which is fixed to the car, you can actually align these yourself with a laser level but once you’ve stopped it wobbling you’ll probably not need to, use your old mount if it’s not damaged as the ball head screws are at the correct adjustment or use the new mount and measure the screws to match the old one, yours however sounds like it’s popped out of the black clips or the clips are broken/pushed backwards.

 

[Nuno1]

I had a look at the radar last night and it was the trim around it that was rattling sorry, anyways i brought it to a local VW/Audi specialist close to where I work and they scanned it with VCDS and I got the great news that my radar is dead, they diagnosed the wiring as being okay but noticed broken clips for the connector on the back of the radar, worst thing is the dealer told me this radar unit was functional and that the cruise control was operational, I even have screenshots of the advertisement of the car online with cruise control as a listed feature, now I got the VCDS fault code sheet printed out and the fault for “no communications with cruise control (Front) distance sensor” has a time stamp with it with the fault having occurred a few days previous to me picking up the car for collection, now I’m considering taking it back to the garage I bought it from, what chance do you guys think I have? The cars gearbox and engine warranty was only 3 months and I’ve got it 4 months now however it was sold to me with this problem outlying and advertised as having cruise control? The guy I was dealing with at the dealer told me outright that the start/stop error which I was compensated for was caused by a different sensor which did not affect the cruise control system in any way, I asked him this exact question as this was what I was afraid of when seeing these errors that if that radar sensor was compromised it would be very costly to fix, any thoughts on the matter are much appreciated, I was told these units new cost over 1500 euros from VW, thanks guys.


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[Carlosfandang0]

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/293157687520

What was the exact fault Code? Was it - U0235 Lost Communication with Cruise Control Front Distance Sensor,

If so you should probably get yourself a new radar such as the one linked above, if you make sure it’s clipped in correctly to the 3 black clips and that the 3 ball headed screws are set at the same lengths as your current one you will NOT need a calibration done, then as long as the new radar is working properly your front assist and cruise AND start stop will all work again.

 

[Carlosfandang0]

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/293157687520

What was the exact fault Code?

Have you made sure it’s connected properly? And I mean MADE SURE! are all of the wiring terminals seated in the connector correctly? How exactly did they test the wiring?

EDIT: no idea how I managed to quote myself!

 

[Nuno1]

Have you made sure it’s connected properly? And I mean MADE SURE! are all of the wiring terminals seated in the connector correctly? How exactly did they test the wiring?

EDIT: no idea how I managed to quote myself!

Yes that was the exact fault code U0235, there is a few other faults which I believe are related to the acc sensor not working such as function restricted due to interrupted communications U1110 and missing messages U1121, what’s puzzling me though is that the u0235 fault for no comm with acc sensor is logged on VCDS as having a fault frequency of 1 yet the reset counter is at 32, this fault occurred at 2019.03.22 so does this mean since that time the ACC radar has been passing its self tests? Either way I will strongly consider replacing the radar soon, I’m going to check this myself soon when I get the chance I am not sure how they did it at the garage or whether they removed the connector to check this, would removing the connector affect the sensor adversely if it was working? If not I will test for a good ground and continuity before I order a new radar, thanks for the continued support


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[Carlosfandang0]

Yes that was the exact fault code U0235, there is a few other faults which I believe are related to the acc sensor not working such as function restricted due to interrupted communications U1110 and missing messages U1121, what’s puzzling me though is that the u0235 fault for no comm with acc sensor is logged on VCDS as having a fault frequency of 1 yet the reset counter is at 32, this fault occurred at 2019.03.22 so does this mean since that time the ACC radar has been passing its self tests? Either way I will strongly consider replacing the radar soon, I’m going to check this myself soon when I get the chance I am not sure how they did it at the garage or whether they removed the connector to check this, would removing the connector affect the sensor adversely if it was working? If not I will test for a good ground and continuity before I order a new radar, thanks for the continued support


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No, unplugging it won’t affect the radar, unplugging a perfectly functioning radar will also throw the U0235 Code, so that’s why I suggest you are sure it’s currently connected before replacement, you say there are broken clips on the connector so best to double check it’s seated properly first, the other codes may not be related but are likely due to the CAN system not receiving information from the radar when requested.

 

[Nuno1]

No, unplugging it won’t affect the radar, unplugging a perfectly functioning radar will also throw the U0235 Code, so that’s why I suggest you are sure it’s currently connected before replacement, you say there are broken clips on the connector so best to double check it’s seated properly first, the other codes may not be related but are likely due to the CAN system not receiving information from the radar when requested.

Okay thank you I decided to have a look at myself when I came home from work today, using a multimeter I checked for power 12.1V on pin 8, low resistance to ground on pin 1 about 4 ohms, and voltage on the can high and can low bus with it being about 1.9 and 3.5v respectively, my multimeter is old so I don’t expect these figures to be spot on but there was enough of a difference to confirm I’m getting can high and low voltage and final test I did was testing power by sticking 2 small needles in the connector, one in pin 1 and the other in pin 8 and checked voltage accross the 2 pins and this reading was the same 12.1v from before so I believe the car wiring loom is okay, there were no pins occupying sockets 5 and 6 on the connector for the front camera, i really gave it a good shove up onto the mating connector on the radarsensor when re installing after I inspected the pins for corrosion and all checked out in that department, I can’t be sure for certain how well the pins are seated in the sockets though I can’t figure out a way to test this properly but the engagement between the connectors feels positive, I think my radar unit is shot, have you heard of anyone trying to open one of these units up to diagnose a fault within or is it best to replace them rather than trying to repair? Thanks for the help


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[Carlosfandang0]

Opening it up may be more hassle than it’s worth, if it were me I’d just replace it and hope it fixes it, you may need to clear the fault codes once you’ve replaced it and a short drive may be necessary to finalise the replacement.

 

[IWMTom]

I had a look at the radar last night and it was the trim around it that was rattling sorry, anyways i brought it to a local VW/Audi specialist close to where I work and they scanned it with VCDS and I got the great news that my radar is dead, they diagnosed the wiring as being okay but noticed broken clips for the connector on the back of the radar, worst thing is the dealer told me this radar unit was functional and that the cruise control was operational, I even have screenshots of the advertisement of the car online with cruise control as a listed feature, now I got the VCDS fault code sheet printed out and the fault for “no communications with cruise control (Front) distance sensor” has a time stamp with it with the fault having occurred a few days previous to me picking up the car for collection, now I’m considering taking it back to the garage I bought it from, what chance do you guys think I have? The cars gearbox and engine warranty was only 3 months and I’ve got it 4 months now however it was sold to me with this problem outlying and advertised as having cruise control? The guy I was dealing with at the dealer told me outright that the start/stop error which I was compensated for was caused by a different sensor which did not affect the cruise control system in any way, I asked him this exact question as this was what I was afraid of when seeing these errors that if that radar sensor was compromised it would be very costly to fix, any thoughts on the matter are much appreciated, I was told these units new cost over 1500 euros from VW, thanks guys.


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How do Consumer Rights work in Ireland? In the UK, we have 6 months where it's up to the dealer to prove the fault didn't exist at the point of sale.

The dealer you bought it from should fix it.

 

[Carlosfandang0]

As mentioned above, you should really take it back to where you purchased it, especially as you can prove the fault occurred prior to your collection, but I personally would have done this as soon as I realised there was a fault! The outcome will really depend on what kind of people they are, if it becomes a battle then replacing the radar yourself may be the easiest thing to do, those older “dome” type radar are usually pretty hard to find so missing out on the one I linked may mean more cost later, you may well be able to use a later flat one but I’m unsure on that! Probably worth checking the part number of your current radar too, either printed on the label on the back or listed in the VCDS scan, but as said, take it back, you’ve nothing to lose, I take it this wasn’t a VW dealer? Judging by only 3 months warranty I’m guessing not.

 

[Nuno1]

I bought the car just accross the border in Northern Ireland so UK consumer rights rules apply which means I’m still within that 6 month period where the dealer has to prove the fault didn’t exist, yea I should’ve taken it back sooner, when I purchased the vehicle, the dealer told me the stop start system was not working, me not intending to use that agreed to 400 euros off the original asking price as compensation, I specifically asked him however was the radarsensor fine and would the faulty sensor he referred to as causing the stop/start not to work, affect any other system in the car to which he told me it would not, those were not true statements, yes I got my part number for the Radar it begins with something like 5Q0 and ends with the letter G, I’ve sourced a replacement in a local scrapyard using partsfinder and I’m being quoted 100 euros for the part however I’ve no way of knowing whether it works or not, I may purchase that part on eBay you listed as it does mention it’s in working order and I believe it’s the exact part number as mine, if I’m able to fit it without having to recalibrate it, I should only have to pay for protection removal and coding of the part, would a VW approved dealer do this for me? Considering it’s not a grand new part supplier by them? I’m going to go after the dealer I purchased the car from in the meantime, and see what they have to say, thanks once again for the help guys much appreciated


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