Originally Posted by tag824
Nothing to worry about, what you're hearing is the low pressure pump priming the fuel system. It should only make that noise for a couple of seconds. Completely normal and part of the update.
no wonder my has that wacking sound, too
...i didn't get annoyed since the car has been performing normal since...
the problem is that i got it CPO last May and haven't received the recall notice, last time engine light on with all the symptoms and had to replace all 6 fuel injectors (flash of course failed the previous day)