Resolving key learning mode stuck issue on VW MQB49 5C by Keydiy & Yanhua ACDP.
Scenario:
Vehicle: 2021 VW Jetta (Mexico)
Condition: All keys lost
Tools used: Keydiy KD-X4, Yanhua ACDP2, Dealer pre-coded key
Problem:
Despite successful key detection and learning mode activation, the vehicle will not start. The screen shows a persistent “1-1” code, indicating the ECU is stuck. No SFD. Power boost was applied but did not help.
Step-by-Step Solution:
Disconnect Power: Open the bonnet. Remove the negative (-) terminal from the battery.
Wait: Leave the battery disconnected for 10 minutes.
Retry: Reconnect the terminal and perform the key programming sequence again.
User Feedback (Confirmed):
“Update: Fixed. I disconnected the negative battery for 10 minutes, reconnected, and reprogrammed the key. Now it starts perfectly.”