Programming and Relearning

AH54.21-P-0004-01X Notes On SCN Coding Of Control Units


The "Software Calibration Number" (SCN) is specified by law in Europe and USA for all control units relevant to exhaust emission as of model year 2002.
Accordingly the software and coding of such a control unit must be clearly identifiable by means of the SCN. As a number the SCN consists of 16 numbers. The first 10 places correspond to the object number to be coded (mostly object number of control unit software). The next 2 places designate the manufacturing plant or field organization, in which the vehicle has been coded. The last 4 places are a number of the variants of the coding string of the vehicle-specific as-built configuration. This number is serially numbered for each newly formed variant.

If special equipment has been installed or removed in the vehicle (e.g. retrofitting a telephone), these retrofit codes must be added to the central system before requesting the SCN coding data. The appropriate national organization must be contacted (MPC) for this.