Audi SQ8 ECU Failure Leads to Power Loss

As someone with moderate experience in car diagnostics, I dealt with a very similar issue on my 2020 Q7. The symptoms you describe match my experience exactly, sudden power loss and engine performance warnings. Initially I suspected the ECU, but after professional vehicle electronics testing, it turned out to be a faulty main relay. This component is crucial for proper engine performance and ECU function. The repair involved: 1. Complete diagnostic scan 2. Testing of electrical connections 3. Main relay replacement 4. ECU system reset 5. Final performance verification Total cost was 120 Euro including parts and labor. The whole process took about 2 hours. Before jumping to conclusions about the ECU, you should get a proper diagnostic scan. Could you share: What error codes are showing? Does the issue happen when the engine is cold or warm? Are there any other electrical issues like flickering lights? Have you noticed any warning lights before the power loss? This would help determine if your case is similar to what I experienced with the main relay or if it points to a different automotive electronics issue.

As someone with moderate experience in car diagnostics, I dealt with a very similar issue on my 2020 Q7. The symptoms you describe match my experience exactly, sudden power loss and engine performance warnings. Initially I suspected the ECU, but after professional vehicle electronics testing, it turned out to be a faulty main relay. This component is crucial for proper engine performance and ECU function. The repair involved: 1. Complete diagnostic scan 2. Testing of electrical connections 3. Main relay replacement 4. ECU system reset 5. Final performance verification Total cost was 120 Euro including parts and labor. The whole process took about 2 hours. Before jumping to conclusions about the ECU, you should get a proper diagnostic scan. Could you share: What error codes are showing? Does the issue happen when the engine is cold or warm? Are there any other electrical issues like flickering lights? Have you noticed any warning lights before the power loss? This would help determine if your case is similar to what I experienced with the main relay or if it points to a different automotive electronics issue.

Last serviced at 147668 KM. After your comments, I had similar thoughts about the relay, but my engine control diagnostic report shows different error codes. The main ones are P0234 and P0299, which point toward a possible turbocharger issue rather than an electrical fault in the computer module. The power loss happens consistently now, both cold and warm. No other electrical problems or warning lights appeared before this started. Going to have the boost pressure and wastegate actuator checked next week, as these seem more likely culprits than the vehicle electronics system based on the specific codes. Will update the thread once I know more about the actual cause. If anyone else has experience with these particular error codes on the SQ8, please share your repair outcomes.

Last serviced at 147668 KM. After your comments, I had similar thoughts about the relay, but my engine control diagnostic report shows different error codes. The main ones are P0234 and P0299, which point toward a possible turbocharger issue rather than an electrical fault in the computer module. The power loss happens consistently now, both cold and warm. No other electrical problems or warning lights appeared before this started. Going to have the boost pressure and wastegate actuator checked next week, as these seem more likely culprits than the vehicle electronics system based on the specific codes. Will update the thread once I know more about the actual cause. If anyone else has experience with these particular error codes on the SQ8, please share your repair outcomes.

Thanks for the update on those error codes. When my Q7 showed P0234 and P0299, it also turned out to be unrelated to the ECU problems I initially suspected. The turbocharger system was indeed the root cause. The fix in my case involved: Replacing a cracked boost pressure sensor, Cleaning the wastegate actuator, Performing a control system adaptation Total repair cost came to 450 Euro, significantly less than a full turbo replacement. The system reset after the repair cleared all error codes and restored full power. These codes typically indicate overboost/underboost conditions. Before assuming major turbo failure, have them check: Boost pressure sensor connections, Wastegate actuator function, Intake system for leaks, Turbo control solenoid Your mileage is similar to when I had this issue. Regular scheduled maintenance of the turbo system can help prevent these problems. Looking forward to hearing what they find during your diagnostic check.

Thanks for the update on those error codes. When my Q7 showed P0234 and P0299, it also turned out to be unrelated to the ECU problems I initially suspected. The turbocharger system was indeed the root cause. The fix in my case involved: Replacing a cracked boost pressure sensor, Cleaning the wastegate actuator, Performing a control system adaptation Total repair cost came to 450 Euro, significantly less than a full turbo replacement. The system reset after the repair cleared all error codes and restored full power. These codes typically indicate overboost/underboost conditions. Before assuming major turbo failure, have them check: Boost pressure sensor connections, Wastegate actuator function, Intake system for leaks, Turbo control solenoid Your mileage is similar to when I had this issue. Regular scheduled maintenance of the turbo system can help prevent these problems. Looking forward to hearing what they find during your diagnostic check.

Based on the workshop results, you all were right, it wasnt an ECU repair situation at all. The mechanic found a split in the intercooler pipe causing boost leaks, triggering those turbo-related codes. They pressure tested the entire system and located the exact crack point. The fix was straightforward: Replacement intercooler pipe, New clamps and seals, Basic system reset to clear codes, Test drive verification Total cost was 280 Euro for parts and labor. Much better than the potential 2000 Euro+ for turbo work I was worried about. The engine control system and computer module are working perfectly now that the boost leak is fixed. Full power is restored and no more error codes. Thanks for helping me avoid jumping to conclusions about needing major ECU work. Will definitely pay more attention to checking all boost system components first if this happens again.

Based on the workshop results, you all were right, it wasnt an ECU repair situation at all. The mechanic found a split in the intercooler pipe causing boost leaks, triggering those turbo-related codes. They pressure tested the entire system and located the exact crack point. The fix was straightforward: Replacement intercooler pipe, New clamps and seals, Basic system reset to clear codes, Test drive verification Total cost was 280 Euro for parts and labor. Much better than the potential 2000 Euro+ for turbo work I was worried about. The engine control system and computer module are working perfectly now that the boost leak is fixed. Full power is restored and no more error codes. Thanks for helping me avoid jumping to conclusions about needing major ECU work. Will definitely pay more attention to checking all boost system components first if this happens again.