The "Code-A-Wash" is the component inside the kiosk that generates codes and sells the packages, so there is no way to add a card reader. If you are asking about the older style hex-headed coinbox that we used to sell as a Code-A-Wash III Coinbox, I'm sorry, but those units were never developed with a card reader option.
On some of those older-style coinboxes, we have had some sites install an RFID reader (Xpress-Wash) and tie those into a
coin mech to activate the machine, but I don't know of anyone that's developed an auxiliary card reader for them.
For the AMTT, AMTT-CS, PaySmart and Enteract coinboxes, we can have a card reader option, and we use a device called InstaGuard which handles card processing.