OnlineTool After replacing an electronic control unit, you may need to restore a function that previously worked. Installing software and coding the unit may be insufficient: some functions require separate permission.
In systems using SFA, that permission is passed in a token. This guide explains the mechanism, the factory feature token package and how to check the result.
What SFA means
SFA means Secure Feature Activation. This mechanism manages individual control unit functions, allowing them to be activated or deactivated.
The installed unit must implement SFA. The same function name in two vehicles does not establish that its permission is applied in the same way. Choose SFA according to the installed system, rather than the model and year alone.
A token contains prepared permission data for a protected function. The program writes it to the relevant unit. Applying it includes checking whether it matches the vehicle and function.
Each function has an identifier used by the program. E-Sys calls an individual function a feature. A unit can have several listed features, each with its own state.
Activation, coding and programming
Programming installs a unit's software. Coding provides settings for the vehicle's equipment. SFA manages permission for a protected function.
After a repair, the unit may have the correct software and settings while a factory function remains inactive. If it uses SFA, check its state and the appropriate permission. Repeating coding does not create that permission.
A token does not install missing equipment or change the unit's software. The function also needs the appropriate unit, software and settings. SFA addresses its part of the job.
How SFA differs from FSC
Both FSC and SFA relate to permissions for functions. FSC uses its own codes and application procedures. SFA manages permissions through protected tokens.
One vehicle may use FSC and SFA for different functions. The correct method depends on the unit and the permission's purpose. Apply an SFA token through an SFA procedure; use the corresponding FSC procedure for FSC.
Identify the mechanism used in the installed unit and how it reports the required permission's state before selecting data.
What the SFA service provides
Preparation requires the complete VIN, the vehicle's 17-character identification number. It is used to prepare tokens for the available factory SFA features.
An SFA package is a set of these tokens. Its contents depend on the vehicle data. Receiving a package does not purchase any arbitrary new option: the tokens relate to particular factory functions of that vehicle.
If a newly prepared package is needed, request it for that vehicle's factory feature set.
Save the result for application later. Keep it in the job folder with a note of the vehicle and repair purpose so it is not confused with another car's results.
Why VIN is enough to request a package but not to work with units
The service uses VIN to prepare the result. When working with the vehicle, E-Sys also needs information about the installed units and software.
SVT Actual describes the actual unit configuration. E-Sys uses it to display the devices using SFA. After a replacement, work with data describing the equipment currently installed.
Retrieving a result by VIN is not a vehicle diagnostic check. Connect to the units to read feature states. This shows which features are active or inactive and which unit they belong to.
Example: restoring a factory function in E-Sys
The job is to restore a factory function after replacing a unit. The function has been identified as using SFA, and a suitable token response has been prepared for the vehicle.
The following procedure refers to the standard SFA module in E-Sys 25.10.01, on the Offline tab. It uses a prepared response. Reading and writing require a vehicle connection.
1. Read the vehicle data
Establish the connection and open SFA. Read or load SVT Actual. E-Sys builds a tree of units using SFA.
Read VIN from the vehicle. When SVT is loaded from a saved file, enter VIN in the relevant field. It must belong to this vehicle.
2. Read feature states
On Offline, use Read actual SFA state. E-Sys queries the units. Expand them to view their features and states.
This is the starting point for comparison: it shows the required feature's state before applying tokens.
3. Select the prepared SFA response
In the lower Secure Feature Activation section, select the response in File Name using …. This section contains Write SFA token, the action for writing SFA tokens.
The standard module processes all SFA units displayed in the tree. It does not provide selection of one individual unit, so understand which features the response covers before proceeding.
Check incl. DELETE Token before writing: it allows deactivation of features absent from the target set. Deactivating other features is not part of this restoration example.
4. Apply the response and read the states again
Write SFA token extracts tokens from the selected response and writes them to the corresponding units. Check the program messages, then use Read actual SFA state again.
For this job, the required feature should show an active state. Check its operation in the vehicle as well. Together, these checks establish that the permission was accepted and the function was restored.
If the function is still unavailable
First inspect the write result and the new feature state. If the token was rejected, keep the exact message with the unit and package details.
If SFA shows the expected state but the function still does not work, check software, settings and equipment. Requesting another package without examining the result does not explain the cause.
The job ends with two checks: the unit accepted the required permission, and the function works in the vehicle. Receiving a file confirms only that the data have been prepared.
Obtain factory SFA tokens
Provide the complete VIN for the available factory feature set. Apply the response through the SFA procedure and check feature states afterwards.
Orders are handled through the Telegram bot. Open the bot from the service page, check the selected service and follow its input instructions. Keep the result for the original procedure.