Are you sure you are entering the code correctly? The correct sequence is to toggle the 1 button until the first digit displayed is correct, then the 2 button for the second digit, etc Once the LCD display shows the correct code, press 5 You dont just tap the code in using the numbers like a calculator - that would be too easy! Yes I'm definitely putting the code in correctly. Although the unit was not properly flush with the dash fascia. Just pressed it this morning and heard a spring loaded part click into place, shall try again later today. I've heard disconnecting the unit from all power for over 24 hours sometimes works? Probably a stupid question but should the unit be completely locked into place before the keycode is accepted? Is this a function of the 6000CD player head unit? The other change is a scotch connector on the orange/black back light power wire of the unit to my trip computer which I installed yesterday, can't see how this would affect it though!