The attack occurred in an area rife with militia activity near the village of Kaita, which is close to Cameroonian border
"The battalion was carrying out a patrol... when 1 of its vehicles hit an explosive device," the peacekeeping mission MINUSCA said in a tweet.
MINUSCA head Valentine Rugwabiza condemned "the use of explosive devices by armed groups," but no militia was directly blamed for the attack.
MINUSCA said it has launched an investigation into the explosion.
Central African Republic has been rocked by violence since 2013 when mainly Muslim Seleka rebels ousted then president Francois Bozize, prompting reprisals from mostly Christian militias.
The conflict has uprooted more than one million people, according to the U.N.
Violence waned after a shaky peace accord was signed in February 2019 between the government and 14 armed groups, but the situation remains volatile. Large areas of territory are still outside government control in one of the world's poorest countries.
U.N. peacekeepers were deployed to CAR in 2014. The mission currently counts just over 14,200 uniformed personnel and has suffered 147 fatalities, its website says.