Error code occurred during ECU upgrade (5021-27-7F33)

Symptom: ECU upgrade in progress, error code [5021-27-7F33]


Cause: 33 negative response from the controller to the ECU upgrade security command



1. It is necessary to check which function of the automatic mode/manual mode was used to upgrade the ECU.
2. If it was performed in manual mode, it is necessary to check whether the ECU upgrade was attempted in a small category suitable for the controller.
3. It is necessary to check whether the car is equipped with aftermarket equipment.
4. It is necessary to confirm that there is no work done on the gateway mounted on the vehicle.
5. If it still does not solve the problem, you should contact the controller manufacturer or automobile research institute.


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