Audi SQ7 TDI Overheating with CAN Bus Control Error

I faced comparable symptoms with my 2016 Audi Q7 TDI. The control module communication fault turned out to be more complex than initially suspected. The data link connector between the engine control unit and cooling system was severely corroded, causing intermittent communication failures. The wiring issue affected multiple systems, triggering both overheating and check engine warnings. After thorough diagnosis, the problem stemmed from coolant seeping into the control unit wiring harness through a deteriorated grommet, creating a chain reaction of electrical problems. The repair required: Complete replacement of the engine control module wiring harness, New coolant temperature sensors, Replacement of damaged control unit connectors, System-wide diagnostic reset This was indeed a serious problem that could have led to complete engine failure if left unaddressed. The combined symptoms you describe strongly suggest a similar underlying issue. A proper diagnosis requires specialized diagnostic equipment to trace the communication fault through the CAN bus network. Would strongly recommend having this checked at a shop with experience in automotive electrical systems, as improper repair can damage additional control modules.

I recall having that exact issue with my SQ7. Your response really caught my attention since the CAN bus communication fault in my case also stemmed from coolant damage to the wiring. The mechanic diagnosed it as a communication error between multiple control modules, very similar to what you described. Your repair list matches what I needed almost exactly. Been curious though, what did the total repair cost end up being for you? My case was several months ago and wondering if any other issues surfaced since then? The data link problems can sometimes indicate larger electrical concerns that show up later.

Got my Audi back from the shop last week actually. Happy to report the control unit communication error has been fully resolved. The diagnostic trouble code is gone and everything is running perfectly now. The main issue was indeed the cable connection to the component, which had degraded due to coolant exposure. The mechanic found and repaired the faulty wiring issue for 95 Euro, which was much less than I initially feared. No additional control module problems have appeared since the fix. The communication fault was isolated to that specific connection, so fortunately the broader CAN bus system remained unaffected. Regular monitoring shows all control units are now communicating properly with no error codes reappearing. Looking back, catching this early likely prevented more extensive damage to other electrical components. The cooling system is now working as intended with no leaks or overheating warnings.

Thanks for checking back. After taking it to an authorized Audi service center, the entire repair ended up costing 2800 Euro. The communication fault was fixed by replacing the damaged wiring harness and several corroded connectors. They also found and sealed the coolant leak that was causing the original connectivity issue. The software glitch in the control modules cleared up once they replaced the damaged components. Been driving it for about 3 months now without any warning lights or overheating problems. The CAN bus system is working perfectly and all diagnostic trouble codes have stayed clear. The shop did a thorough job documenting all the repairs, showing me exactly where the coolant had damaged the wiring. While expensive, having it properly diagnosed and fixed by specialists was worth avoiding further electrical damage. Really glad I caught it before it led to more serious issues.