Hi, I've rechecked and my calculator gives the code as 2322 based on your given serial number M391554 if this will not work it means either the radio has been re-coded and if so you will have to take it to a specialist and have it re-coded again or you are not entering the code correctly have a look at www.davidsonelectronics.co.uk/code_entry.htm this gives you step by step instructions on entering your code
nigel, May 2008
