To change CO on the 15RC is only possible when lambda regulation is disable in the map.
The "writer" software is IAW15xEEPROMTool V0.04 (15M, 15P, 15RC), reader and writer in all, download and upload an eep file from EEPROM in ECU, it's an another data section as the map. To change use Tunerpro and matched XDF. Very fast and easy way to set CO. For software / XDF download visit the GuzziDiag website.