Key issue?

That code is VW code for "The network sees something missing". It doesn't really tell you anything about the real problem. The Central Electronics is one of the cars' primary network controllers, but it doesn't tell you what it sees as the problem. For that you would need a VAG compatible scan tool and be able to test the system to find out what module(s) are showing codes. From your description it is likely in the keyless entry and starting system but there are 4 different modules related to that which you would need to test. There are various scan tools out there that would work but by the time you get the scan tool, then the test information and determining the problem, you still need to get the module and program it into your car, then program in your keys so the system works. To do that most of the lower cost scan tools are out and you are into the mid range professional level tools in the $2-3K range. You might check out www.ross-tech.com to see what they have pricing wise.