Error code occurs during ECU upgrade (5021-81-7000)

Symptoms

Possible Causes

• ECU installation issue: Incorrect physical installation may result in unstable communication.
• ECU Condition issue: The ECU may be in an unstable condition, preventing proper communication.

Solution

1. Check physical installation – Ensure that the ECU is installed correctly.
2. Restart the ECU – Turn off power to the ECU, restart it, and then retry the upgrade.
3. IBU-BCM power reset – If the issue is related to the BCM, turn off the power and retry the upgrade after 2 hours.

Additional Support

This error indicates that the vehicle’s ECU (Electronic Control Unit) cannot communicate properly, causing the upgrade to fail.

1. If the problem persists after completing the basic troubleshooting steps, such as retrying the upgrade and checking the battery condition, please contact your NSC (National Distributor) for support.

2. If necessary, we can provide a special file set with an extended ECU response time to support another upgrade attempt.

3. However, depending on the ECU Condition, the upgrade may still fail when using the extended file.

4. If you have already tried reinstalling or reconnecting the ECU hardware and the issue persists, ECU replacement or additional support from the vehicle manufacturer may be required in accordance with guidance from the automotive quality department.