Tuners often download a "stock" file from a vehicle, modify it using software like WinOLS, and then need to write the "new" tuned file back to the car.
Automatic Checksum Correction: Standard safety feature that verifies and corrects the file checksum before writing to the ECU to prevent bricking. kess 290 download new
: Download the software from reputable sources or authorized distributors. Original tools typically use the Alientech Suite modify it using software like WinOLS