Error Code Occurs During ECU Upgrade (1000-C8-0027)

Symptom: Error code [1000-C8-0027] occurs during an ECU upgrade.

Cause: Socket connection failure during Ethernet event security authentication.

Solution:

1. Check whether any aftermarket equipment is installed in the vehicle.
2. Check that the ECI cable is properly connected and that a static IP address is configured on the tablet.
3. Connect the diagnostic tool and verify that the gateway controller sensor output is displayed correctly.
4. Disconnect the vehicle power connector, wait 5 minutes, and then reconnect it. After completing these steps, retry the ECU upgrade.