I have zx radio manual and it says after each of the first two attempts the radio will be locked for ten seconds At the end of the 10 second period the display will again read C.O.D AFTER THE THIRD INCORRECT ATTEMPT THE UNIT WILL BE LOCKED FOR 1 HOUR TO MAKE ANY FURTHER ATTEMPTS THE UNIT MUST BE SWITCHED ON AND LEFT UNTOUCHED FOR 1 HOUR. AFTER THE 20TH ATTEMPT THE UNIT WILL BE LOCKED PERMENANTLY IN THIS CASE CONTACT YOUR LOCAL CITROEN DEALER YOU NEED PROOF OF OWNERSHIP IF YOU DO GO SO DONT FORGET YOUR DOCUMENTS
STEVE ZX OWNER, October 2008