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Discussion Starter #1
Hello All.

My ACC/Park Assist system developed a fault a few days ago that is intermittently displaying the "unavailable" error with a high frequency, i.e. system activates for a few seconds then shuts down for seconds/minutes, and re-activates again. Then rinse and repeat. This would be annoying in itself, but the annoyance is highly compounded by the fact that the back-up camera is also inop, as it's apparently tied to the same components, and every time the system goes down, and/or car stops, several alert tones start chiming. And no way to shut them off. Diagnostic codes show an undervoltage and a short. Dealer ran the test plan and discovered that the parking aid control module (7P0907801-G) is not communicating with any of the sensors. Recommendation is to replace the module, which is apparently an almost $2k job. The part itself is about $700. Car has almost 70k miles and no extended warranty, with the exception of the VW TDI emission-related coverage, which doesn't seem to include this repair. Has anyone had this issue? Any suggestions?

Thanks.
 

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I have had ongoing issues with ACC since 2016 (within one year of purchasing it new). I’ve been offered various explanations / repairs including replacement of the bracket that holds the right sensor (told 3 times that it was cracked) and I had the cruise control module replaced. The problem is still there. Sporadically cuts out when I’m driving. The car is off warranty and I’m now out-of-pocket approx $3000 for repairs! Last time I was in for servicing I was told (again) the bracket was broken and i had it replaced. I also got a safety done on the vehicle with the intention of selling it. BUT the problem persists and I wouldn’t feel right about selling it privately. The dealership that sold me the vehicle new and where I’ve had all of my servicing done values the vehicle less than what I feel it’s worth!
 

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Discussion Starter #3
Sounds terrible. Sorry to hear! My problem disappeared for a couple of weeks while waiting for the module to arrive from Germany, but then re-appeared last week right after the car came out of service for a recall emissions software update. Dealership also reset diagnostics errors and washed it - I'm guessing that the latter was responsible for the re-emergence of the fault, which is behaving like a short at some connector or wire. I am very reluctant to have the module replaced, as I don't think think that this will fix the issue. Have another diagnostic scheduled in a couple of days, and dealership promises to reach out to VW to get an additional opinion. Hopefully can get this resolved, although your story doesn't inspire much confidence...
 

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Last week, I had a technician drive my vehicle for 2 days putting on over 300 KMs. The ACC never cut out once. The source of the problem is looking like an environmental one. There’s 2 areas on a particular stretch of highway where the ACC cuts out repeatedly. The only environmental issue that I can see is electric fencing that encloses a farmer’s field. If it’s a problem with the car, the technician says the ACC should malfunction no matter where I drive. I’ll continue to log time, location and photo of error message on instrumentation panel, each time the ACC cuts out.

safe to say, the module and brackets holding the sensors have been ruled out.
 

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Discussion Starter #5
Yeah, I've had ACC cut out occasionally in heavy snow/rain, but that's by design. Haven't had much opportunity to drive by electric fencing... Issue I have now is different. Just a constant intermittent fault that sets off the dinging every few seconds. Quite annoying. Not to mention that Front Assist and cameras are also non-functional. Dealer was going to replace a control module but now dropping both bumpers to look at the sensors, apparently on VW's advice. Will be about a grand in diagnostics. Hope they fix the thing... I may be headed down your path, unfortunately.
 

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Discussion Starter #7
All fixed. Took a long time to diagnose. Turned out to be a corroded wire harness behind the front bumper. Part #7P6-971-095-AD. Total cost was ~$1200, most of that (~$1k) in labor. The bumper was disassembled ~3 yrs ago and it appears that the harness was pinched upon re-assembly, which led to the corrosion. So I was reimbursed, fortunately.
 

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Well that’s certainly something that the mechanics haven’t considered in my case! I had the front bumper disassembled too, shortly after buying the vehicle. Replacing brackets and the module isn’t the source of the problem because it continues to cut out randomly. Environmental factors have now been deemed the issue because it’s been happening regularly on a specific stretch of highway, where electric fence exists. But as time wears on, it’s starting to cut out elsewhere as well. I will definitely share the source of your problem with the mechanic. Thank you!
 
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