Например, можно так:
$fh = fopen("file.csv", "r");
while (false !== $row = fgetcsv($fh, ...)) {
foreach ($row as &$rowItem) {
$rowItem = mb_convert_encoding($rowItem, "utf8", "cp1251");
}
unset($rowItem);
...
}
fclose($fh);
P.S.
Toster Driven Development
