VW Polo TDI ECU Memory Lock Blocks Diagnostics

I had a very similar issue with my VW Golf TDI from 2016. As someone with moderate experience in car maintenance, I initially tried reading the fault codes myself using a basic OBD scanner, but the ECU diagnostics were blocked due to the same memory lock condition. After attempting basic troubleshooting like checking battery connections and fuses, I took it to a workshop specializing in automotive diagnostics. They discovered an undervoltage condition in the vehicle electrical system that was causing multiple ECU fault codes to appear. The repair involved: Complete system diagnostic scan, Battery load testing, Voltage regulator inspection, ECU reset and recalibration, Clearing all stored fault codes Total cost was 240€ for diagnostics and repair. The car electronics have worked flawlessly since then, with no recurring fault codes. To better assist with your situation, could you share: Which specific fault codes are showing up? Have you noticed any electrical issues like dim lights or slow starting? Has the battery been replaced recently? Are there any aftermarket electronics installed? This information would help determine if your issue is similar to what I experienced with my Golf.

Thanks for sharing your experience. In my case with 132214km on the clock, the issue turned out different. The active memory problems cleared after replacing the faulty crankshaft position sensor, which was causing sporadic ECU faults and memory lock conditions. My repair steps were simpler: Advanced diagnostic scan to identify root cause, Sensor replacement, ECU reset and code clearing Total repair cost came to 180€ including parts. The car electronics now function normally with no recurring automotive diagnostics issues. The workshop confirmed this is a known fault pattern in these engines at higher mileage. Would like to know if you checked your sensor readings before the voltage repairs?

Thanks for the follow-up about the crankshaft position sensor. Actually, in my Golf TDI case, we did check various sensor readings before proceeding with the voltage repairs. The car electronics showed inconsistent values across multiple sensors, which initially masked the true problem. The workshop ran a comprehensive ECU diagnostics test that revealed voltage fluctuations were affecting the sensor readings. This created active memory issues similar to a faulty sensor, but in our case, the root cause was different. The memory lock condition persisted until the voltage problem was corrected. Looking back, I probably should have mentioned the initial sensor diagnostics in my first response: Multiple sensor readings were unstable, ECU showed unusual communication errors, Active memory contained conflicting data, Computer system indicated voltage-related faults Interesting that your crankshaft sensor was the culprit. These TDI engines seem prone to different issues causing similar symptoms in the automotive diagnostics. Did you notice any specific running issues before the repair?

Thank you for clarifying about the sensor diagnostics. My case involved no noticeable running issues initially, which made the ECU fault codes more concerning. Now that both repairs were successful through different approaches, I think sharing this information could help others with similar TDI issues. When the active memory problems first appeared, the car performed normally despite the ECU diagnostics warnings. The workshop mentioned they frequently see crankshaft position sensor failures trigger memory lock conditions in these engines at around 130000km. For reference, my final repair details: Initial sensor scan cost: 45€, Crankshaft position sensor: 85€, Labor and ECU reset: 50€ The auto repair proved straightforward once properly diagnosed. The key learning was not to ignore ECU fault codes even when the car runs fine. Would definitely recommend getting proper diagnostics at the first sign of computer system warnings.