  Pour une repr\'esentation galoisienne di\'edrale en caract\'eristique l on
\'etablit (sous certaines hypoth\`eses) l'existence d'une newform \`a
multiplication complexe, dont on contr\^ole le poids, le niveau et le
caract\`ere, telle que la repr\'esentation l-adique associ\'ee est congrue
modulo l \`a celle de d\'epart.
  Given a dihedral Galois representation in characteristic l, we establish
(under some assumption) the existence of a CM newform, whose weight, level and
Nebentypus we pin down, such that its l-adic representation is congruent modulo
l to the one we started with.
