VW Up ECU Memory Lock Prevents Fault Code Reset

The ECU fault messages you describe match what I encountered on my VW Polo TSI from 2016. The control unit was showing persistent undervoltage warnings that would not clear through standard diagnostics. After several failed attempts with basic ECU diagnostics, it turned out the car electronics were affected by a failing voltage regulator in the alternator. The car would still run, but the irregular power supply was confusing the ECU systems. The repair required: Complete alternator replacement, ECU reset and recalibration, New battery (the old one was damaged by voltage fluctuations) This was considered a serious electrical system issue that needed immediate attention to prevent potential ECU damage. The car electronics could have been permanently affected if left unresolved. Based on your description, I suggest having the charging system thoroughly tested. The high mileage and age match the typical timeline for these components to start failing. A specialized auto electronics workshop with VW-specific diagnostic equipment would be better equipped to handle this than a general mechanic.

Thanks for sharing your experience with the alternator and ECU problems. The automotive diagnostics you described sound very similar to my situation. I took your advice and had a specialized workshop check the charging system. They found and fixed a similar voltage regulator issue that was causing the memory lock in the ECU. Would you mind sharing what the total repair cost was in your case? Also curious if youve had any recurring ECU fault codes since the fix was done.

Great to hear the specialized workshop identified the voltage regulator problem. Since having my car serviced, the fault memory lock active issue has been completely resolved and the control unit is working perfectly. The automotive diagnostics confirmed it was indeed an undervoltage problem, just like in your case. The total repair cost for my alternator issue came to 240€, which included the parts and labor for the voltage regulator replacement. This was actually less expensive than I initially feared when the ECU fault messages first appeared. No recurring fault codes have shown up in the past 8 months since the repair. The key was having proper diagnostic equipment to identify the root cause rather than just clearing the codes. A regular scan tool often misses these specific electrical system issues, which is why the specialized workshop made all the difference. The active memory is now functioning as it should, with no more error messages or warnings. Just make sure to keep an eye on your battery voltage readings for the next few weeks to ensure everything stays stable.

Thanks for the advice. After dealing with persistent ECU fault messages, I finally got the car properly diagnosed at a specialized auto electronics workshop like suggested. The computer system check revealed the voltage regulator was indeed the culprit. The total repair ended up costing 310€ including parts and labor. More than a basic service but worth every cent since the fault codes have completely cleared. The active memory is working normally again and no more warning lights on the dash. The mechanics used professional diagnostic equipment to properly reset the ECU after fixing the charging system. They also checked the battery health to prevent any future issues. Been driving for 2 weeks now without any error messages returning. Lesson learned, when dealing with complex electrical problems, finding a workshop with the right diagnostic tools makes all the difference. Regular mechanics often lack the specialized equipment needed for these computer system issues.