Q3 Hybrid Hit by Widespread Electrical System Failures

Having dealt with similar issues on my 2021 Q2 Hybrid, I understand your concern about car ECU and electrical problems. Let me share my experience as someone with moderate technical knowledge of hybrid systems. The symptoms you describe match what I encountered, multiple system failures and starting issues caused by power surge conditions. Initially, I also thought the alternator was the culprit, but the actual problem was more complex. My workshop diagnosed a failing voltage converter that was causing circuit protection systems to trigger. Even with a new battery, the faulty converter created overvoltage situations that affected multiple electronic systems. The repair involved: Complete diagnostic scanning, Testing the voltage converter unit, Replacement of the main converter, ECU recalibration, System reset Total cost was 290 Euro and took about 2 days to complete. The fix has been solid for 8 months now with no recurring issues. Before offering more specific advice, could you share: Current battery voltage readings, Specific fault codes shown, Whether issues occur more during acceleration or idle, If the check engine light stays on constantly This information would help determine if your case matches what I experienced or points to a different underlying cause.

Current mileage: 80170 KM Last service: Full maintenance check including battery diagnostics two weeks ago Thanks for the detailed response. After running another diagnostic scan today, I can clarify that the voltage spikes occur mainly during acceleration, with the check engine light remaining consistently on. The battery voltage fluctuates between 13.8V and 16.2V, which clearly indicates a power surge issue. The main fault codes are P0562 and P0563, pointing toward voltage regulator problems. The alternator failure symptoms become more pronounced during heavy electrical load situations, like when using climate control and heated seats simultaneously. I think your voltage converter solution makes sense given the similar symptoms. Will definitely have the workshop check this component first before replacing the entire alternator unit. The car ECU might also need recalibration as you suggested if the circuit protection system has been frequently triggered.

Based on those voltage readings and fault codes, my initial diagnosis of the voltage converter issue seems even more likely. The P0562/P0563 codes match exactly what I saw with my car battery system before the repair. The fluctuation between 13.8V and 16.2V is a classic sign of voltage regulator malfunction affecting the circuit protection system. When my Q2 showed these symptoms, the workshop found the voltage converter was sending incorrect signals to the voltage regulator, causing those power surge spikes during acceleration. One thing I noticed before getting mine fixed, the alternator failure symptoms would worsen in cold weather or when multiple electrical systems were running. This matches your experience with the climate control and heated seats causing increased issues. The repair process I mentioned earlier resolved all these problems. Just make sure the workshop: Tests the voltage converter under load conditions, Checks all ground connections, Verifies alternator output is stable after the fix, Performs a full system reset My total repair ended up being cost-effective compared to a full alternator replacement. The voltage converter unit itself was relatively inexpensive at 180 Euro, with labor making up the rest of the 290 Euro total. Keep in mind circuit protection systems can mask the root cause, so insist on thorough testing of the voltage converter before any major component replacements.

I really appreciate the thorough responses and detailed insights. The voltage readings from my recent diagnostic scan (13.8V to 16.2V) align perfectly with your experience. Those fluctuations during acceleration, combined with the P0562 and P0563 fault codes, strongly suggest a voltage converter problem rather than a complete alternator failure. Your repair process makes perfect sense, testing the voltage converter unit first before replacing costlier components like the alternator. The similar high voltage symptoms during heavy electrical loads and the persistent car ECU warnings match your case exactly. The circuit protection systems triggering frequently also explains the multiple electrical failures. Given that the total repair cost was 290 Euro in your case, this seems like a much more reasonable approach than replacing the entire alternator assembly. Will schedule a workshop visit and specifically request: Voltage converter testing under load, Ground connection inspection, Power surge monitoring, Complete system calibration Thanks for helping narrow down the likely cause. Will update once the repair is completed to confirm if the voltage converter was indeed the root issue.