Update at dealers with Feature Installer already installed

[take0524]

Hello.

I had to replace the head unit because the navigation system would not start when it was updated without returning the OEM before.

When a program update is implemented by the dealer
Do I need to return the HU-NBT with the Feature Installer installed back to OEM?

If so, what should I do?

[Stratofortress]

Feature Installer patches the HU, which means that it changes the certificate signature stored in HU to load custom FSC codes and edits some FDL codes to enable features. Reset HU to OE state before vehicle software update at dealer and restore after the update. For this, If your Feature Installer included OE backup and restore, then do a full restore with Feature Installer as it backs up the original certificates and FSC to a location on the HU. Therefore, before a visit to dealer, run the feature code again and revert all certs and FSC to factory with Feature Installer. After the dealer visit simply patch again the HU with the original feature code. If unable to do so, the HU needs to be flashed, the custom FSC codes wiped, and the OE set of FSC codes loaded to HU. This OE restore process is required before updating the vehicle with ISTA. With E-Sys it does not matter.

[Rob]

Good explanation