A8 4.2 D3 fails to start
 

I´ve a 2006 4.2 A8 and sometimes it doesn´t start in the first attempt. I turn the key to starting directly or first to ignition and then (after 2-3 seconds) to start, and it makes a small crank but it stops inmediatly and doesn´t start. Then I turn the key anti clock wise, start the procedure and it starts ok. This happens sometimes, not always, and it doesn´t depend on engine temperature.

I´ve checked several times with vag com and has no error codes. Only one for an alarm sensor on passenger door.

Has anyone experienced this? Maybe the battery needs replacement?

Thanks in advance

How old is the battery ?
Anything over 4 years is pushing your luck.

Could also be CPS.