Email header and q-encoding

[eluser]christophe2[/eluser]
Hello,

In order to use accents in my email header subject line, I try to q-encode the following string:
=?UTF-8?q?A bient=C3=94t?=

c394 being the hex value for ô.

I can't get the character to display correctedly. Can someone please let me know what I am doing wrong ?
I use standard CodeIgniter Email class.

Thanks for any help,

Christophe