Audi A7 Coolant Leak Points to Control Module Issue

I had a similar issue with my 2016 Audi A6 3.0 TFSI last year. Having some experience with car diagnostics, I initially thought it was just a coolant leak, but it turned out to be more complex. The workshop found a connectivity issue between the cooling system control unit and the main engine management module. After running detailed diagnostics, they discovered a damaged data link cable connecting these components. The wire insulation had worn through, causing intermittent communication failures and incorrect temperature readings. The fix involved replacing the damaged wiring harness and recalibrating the control unit. No need for a complete control unit replacement. The software glitch warnings disappeared after the repair, and the cooling system has worked perfectly since. Before suggesting specific solutions, could you share: Have you noticed any correlation between the overheating and specific driving conditions? Did the issue start suddenly or develop gradually? What specific diagnostic trouble codes are you seeing? Has any recent maintenance been performed on the cooling system? The repair cost me 95 Euro, which included diagnostic work and parts replacement. However, costs can vary based on the exact issue and required parts.

I had a similar issue with my 2016 Audi A6 3.0 TFSI last year. Having some experience with car diagnostics, I initially thought it was just a coolant leak, but it turned out to be more complex. The workshop found a connectivity issue between the cooling system control unit and the main engine management module. After running detailed diagnostics, they discovered a damaged data link cable connecting these components. The wire insulation had worn through, causing intermittent communication failures and incorrect temperature readings. The fix involved replacing the damaged wiring harness and recalibrating the control unit. No need for a complete control unit replacement. The software glitch warnings disappeared after the repair, and the cooling system has worked perfectly since. Before suggesting specific solutions, could you share: Have you noticed any correlation between the overheating and specific driving conditions? Did the issue start suddenly or develop gradually? What specific diagnostic trouble codes are you seeing? Has any recent maintenance been performed on the cooling system? The repair cost me 95 Euro, which included diagnostic work and parts replacement. However, costs can vary based on the exact issue and required parts.

I had a similar issue with my 2016 Audi A6 3.0 TFSI last year. Having some experience with car diagnostics, I initially thought it was just a coolant leak, but it turned out to be more complex. The workshop found a connectivity issue between the cooling system control unit and the main engine management module. After running detailed diagnostics, they discovered a damaged data link cable connecting these components. The wire insulation had worn through, causing intermittent communication failures and incorrect temperature readings. The fix involved replacing the damaged wiring harness and recalibrating the control unit. No need for a complete control unit replacement. The software glitch warnings disappeared after the repair, and the cooling system has worked perfectly since. Before suggesting specific solutions, could you share: Have you noticed any correlation between the overheating and specific driving conditions? Did the issue start suddenly or develop gradually? What specific diagnostic trouble codes are you seeing? Has any recent maintenance been performed on the cooling system? The repair cost me 95 Euro, which included diagnostic work and parts replacement. However, costs can vary based on the exact issue and required parts.

Thank you for sharing those details. After checking my service records with 187185 KM on the clock, I can mention that both the software glitch and overheating started occurring right after my last maintenance service 2 months ago. A scan with a CAN bus diagnostic tool revealed error code P0128 showing issues with the engine coolant temperature. The control module appears to send incorrect signals, especially during highway driving. Suspecting a similar wiring issue since my symptoms match your experience. Would be interested to know if your workshop needed special tools for the recalibration process or if a standard diagnostic scanner was sufficient for the repair.

Thank you for sharing those details. After checking my service records with 187185 KM on the clock, I can mention that both the software glitch and overheating started occurring right after my last maintenance service 2 months ago. A scan with a CAN bus diagnostic tool revealed error code P0128 showing issues with the engine coolant temperature. The control module appears to send incorrect signals, especially during highway driving. Suspecting a similar wiring issue since my symptoms match your experience. Would be interested to know if your workshop needed special tools for the recalibration process or if a standard diagnostic scanner was sufficient for the repair.

Thank you for sharing those details. After checking my service records with 187185 KM on the clock, I can mention that both the software glitch and overheating started occurring right after my last maintenance service 2 months ago. A scan with a CAN bus diagnostic tool revealed error code P0128 showing issues with the engine coolant temperature. The control module appears to send incorrect signals, especially during highway driving. Suspecting a similar wiring issue since my symptoms match your experience. Would be interested to know if your workshop needed special tools for the recalibration process or if a standard diagnostic scanner was sufficient for the repair.

Thanks for the additional details. Your symptoms indeed match what I experienced, especially the P0128 code and the timing after maintenance. In my case, the wiring issue near the CAN bus connections was actually caused by a rushed routing job during that previous service. The workshop used a high-end VAS diagnostic system for the recalibration, though they mentioned a good-quality aftermarket scanner could also work. The critical part was accessing the specific control unit parameters and ensuring proper communication across the CAN bus network. A key finding during my repair was that the wiring issue caused the temperature sensors to report faulty readings, triggering the cooling system to build excessive pressure. The control unit was receiving corrupted data through the damaged wires, leading to incorrect coolant regulation. The fix took about 3 hours, and they performed a thorough check of all nearby wiring harnesses to prevent future connectivity issues. The most important step was verifying the proper signal flow after the repair to ensure no residual software glitch remained in the system. With your mileage being similar to what mine was, its worth having them check the entire harness routing, as age-related insulation wear is common in these models.

Thanks for the additional details. Your symptoms indeed match what I experienced, especially the P0128 code and the timing after maintenance. In my case, the wiring issue near the CAN bus connections was actually caused by a rushed routing job during that previous service. The workshop used a high-end VAS diagnostic system for the recalibration, though they mentioned a good-quality aftermarket scanner could also work. The critical part was accessing the specific control unit parameters and ensuring proper communication across the CAN bus network. A key finding during my repair was that the wiring issue caused the temperature sensors to report faulty readings, triggering the cooling system to build excessive pressure. The control unit was receiving corrupted data through the damaged wires, leading to incorrect coolant regulation. The fix took about 3 hours, and they performed a thorough check of all nearby wiring harnesses to prevent future connectivity issues. The most important step was verifying the proper signal flow after the repair to ensure no residual software glitch remained in the system. With your mileage being similar to what mine was, its worth having them check the entire harness routing, as age-related insulation wear is common in these models.

Thanks for the additional details. Your symptoms indeed match what I experienced, especially the P0128 code and the timing after maintenance. In my case, the wiring issue near the CAN bus connections was actually caused by a rushed routing job during that previous service. The workshop used a high-end VAS diagnostic system for the recalibration, though they mentioned a good-quality aftermarket scanner could also work. The critical part was accessing the specific control unit parameters and ensuring proper communication across the CAN bus network. A key finding during my repair was that the wiring issue caused the temperature sensors to report faulty readings, triggering the cooling system to build excessive pressure. The control unit was receiving corrupted data through the damaged wires, leading to incorrect coolant regulation. The fix took about 3 hours, and they performed a thorough check of all nearby wiring harnesses to prevent future connectivity issues. The most important step was verifying the proper signal flow after the repair to ensure no residual software glitch remained in the system. With your mileage being similar to what mine was, its worth having them check the entire harness routing, as age-related insulation wear is common in these models.

Thanks for the detailed reply about your repair experience. The situation does sound very similar, particularly regarding the control module communication fault showing up after routine maintenance. Based on the diagnostic findings and symptoms you shared, I'm now fairly confident the root cause is wiring-related rather than a failed control unit. I'll have my workshop check the wiring harness routing and CAN bus connections carefully, focusing on any potential damage near recent service areas. Good to know about the VAS system requirement, I'll make sure they have the right diagnostic equipment for proper calibration after repairs. Given the data link issues and similar error codes, I'll also ask them to thoroughly inspect all the coolant temperature sensor connections while they're checking the wiring. With the high mileage, a complete harness inspection makes sense to catch any other potential wear spots. Will schedule the repair next week and update once I know if the wiring was indeed the culprit causing these communication errors and cooling system problems. Hoping for a similar 3-hour repair timeframe and reasonable cost like in your case.

Thanks for the detailed reply about your repair experience. The situation does sound very similar, particularly regarding the control module communication fault showing up after routine maintenance. Based on the diagnostic findings and symptoms you shared, I'm now fairly confident the root cause is wiring-related rather than a failed control unit. I'll have my workshop check the wiring harness routing and CAN bus connections carefully, focusing on any potential damage near recent service areas. Good to know about the VAS system requirement, I'll make sure they have the right diagnostic equipment for proper calibration after repairs. Given the data link issues and similar error codes, I'll also ask them to thoroughly inspect all the coolant temperature sensor connections while they're checking the wiring. With the high mileage, a complete harness inspection makes sense to catch any other potential wear spots. Will schedule the repair next week and update once I know if the wiring was indeed the culprit causing these communication errors and cooling system problems. Hoping for a similar 3-hour repair timeframe and reasonable cost like in your case.

Thanks for the detailed reply about your repair experience. The situation does sound very similar, particularly regarding the control module communication fault showing up after routine maintenance. Based on the diagnostic findings and symptoms you shared, I'm now fairly confident the root cause is wiring-related rather than a failed control unit. I'll have my workshop check the wiring harness routing and CAN bus connections carefully, focusing on any potential damage near recent service areas. Good to know about the VAS system requirement, I'll make sure they have the right diagnostic equipment for proper calibration after repairs. Given the data link issues and similar error codes, I'll also ask them to thoroughly inspect all the coolant temperature sensor connections while they're checking the wiring. With the high mileage, a complete harness inspection makes sense to catch any other potential wear spots. Will schedule the repair next week and update once I know if the wiring was indeed the culprit causing these communication errors and cooling system problems. Hoping for a similar 3-hour repair timeframe and reasonable cost like in your case.