Customer Feedback:
A 2018 VW Polo MQB49 5C came in with a strange key issue. The original key’s remote locking and unlocking functions still work, but the vehicle will no longer start with it. Reprogramming the original key is no longer possible. Interestingly, Xhorse VW MQB and KEYDIY keys can start the vehicle, but their remote functions do not work. The customer has already tried several common solutions without success. What could be causing this problem, and why would the original key lose immobilizer authorization while aftermarket keys can still start the car?
XhorseVVDI.com‘s Engineer Solution:
Key ID issue.
The issue is likely related to the original Key ID stored in the immobilizer data. MQB GEKO online programming relies on this Key ID for authorization. If the Key ID no longer matches, the original key may fail to start the vehicle even though other functions appear normal. In many cases, correcting the original Key ID resolves the problem.
A strong indication is that the two universal keys can still start the vehicle. During key programming, a standard dealer key is generated and synchronized with the immobilizer system. On MQB49 5C vehicles, important key information is often obtained from the original key rather than directly from the cluster, making Key ID consistency critical.
Xhorse vvdi key tool plus has the function to modify original key ID.
When a standard dealer key is added on VAG systems while connected to ODIS, it may invalidate existing keys because the system does not recognize it as a GEKO online authorized key.
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