VW Sharan Memory Lock Diagnosis and Repair Guide

Had a similar issue with my 2008 VW Touran diesel last year, both cars share many electronic components. As someone with moderate experience in car maintenance, I initially tried using a basic OBD scanner but quickly realized this ECU fault needed professional diagnostics. The issue turned out to be undervoltage in the computer system, causing multiple control unit malfunctions and creating a memory lock situation. My workshop ran a complete ECU diagnostics scan which revealed the battery was not maintaining proper voltage, affecting various electronic systems. The fix involved: Full battery test and replacement, Professional reset of all ECU fault codes, System voltage stabilization check, Control unit recalibration Total cost was 240€ and resolved all error messages. The car has run perfectly since then. To better assist with your situation, could you share: What specific error codes are showing? Are you experiencing any drivability issues? When did these symptoms first appear? Have you had any recent battery or electrical work done? This information would help determine if your issue matches what I experienced or points to a different underlying problem.

Just had my latest service done at 103722km, and I totally relate to this ECU diagnostics problem. After reading up on auto repair forums, I tried a basic control unit reset myself, but the fault memory lock persisted. Took it to the workshop where their computer system analysis showed multiple communication errors between control units. The active memory was essentially deadlocked, preventing proper system diagnostics. Would appreciate insight on whether anyone solved this without replacing the ECU completely. The current error codes from my car are all communication-related, which makes me suspect a wiring issue rather than a full control unit failure.

Thanks for the additional details about your Sharan's issues. After successfully resolving similar communication errors on my Touran, I can share some extra insights based on the diagnostic data you provided. The communication errors you mention match exactly what I experienced before the complete fix. In my case, the automotive diagnostics initially pointed to wiring, but the root cause was more complex. The workshop found corroded connections at the main ECU plug, which created intermittent communication issues between control units. The successful repair involved: Cleaning and reseating all ECU connections, Testing communication lines between modules, Clearing the active memory, Performing a full system reset No ECU replacement was needed. The total repair cost was 180€, significantly less than a new control unit. The fault memory lock cleared after addressing these connection issues. My car has completed 20000km since without any computer system errors reappearing. Based on your description, recommend having the workshop check: Connection quality at all control unit plugs, Ground point conditions, Voltage stability across the system These steps should resolve the communication errors without requiring a complete ECU replacement.

Thanks for relating your similar ECU diagnostics experience. The fault codes shown at my last service were P1602, P1603, and U0401, all pointing to communication problems between control units, as you mentioned happened with your Touran. After the workshop cleaned and reseated the ECU connections, they found significant corrosion at two ground points. The active memory lock cleared once they repaired these grounds and performed a full system reset. Total cost was 160€, much better than replacing the entire control unit. The car has now done about 1000km since the repair with no error codes returning. The engine performance is back to normal and all electronic systems are working properly. This experience shows how important it is to properly diagnose these computer system issues before jumping to expensive parts replacements. Will update the forum again after a few more months of driving to confirm the fix remains stable. Thanks again for sharing the details of your repair, it helped point my workshop in the right direction for resolving the fault memory lock situation.