Обновление связей элементов и разделов в 1С-Битрикс

<?php
// Удаляем привязку к разделу "Новинки" у элементов, созданных более 3 месяцев назад
$section_new = 123; // ID раздела "Новинки"
$objDateTime = new \Bitrix\Main\Type\DateTime();
$objDateTime->add('-3 month');

$arFilter = [
    "IBLOCK_ID" => CATALOG_IBLOCK_ID,
    "ACTIVE" => "Y",
    "<=DATE_CREATE" => $objDateTime->format("Y-m-d"),
    "SECTION_ID" => $section_new
];

$arSelect = ["ID"];
$res = CIBlockElement::GetList([], $arFilter, false, false, $arSelect);

$elementIds = [];
while ($element = $res->Fetch()) {
    $elementIds[] = $element["ID"];
}

if (!empty($elementIds)) {
    $result = CIBlockElement::GetElementGroups($elementIds, true, ["ID"]);
    $elementSections = [];
    while ($group = $result->Fetch()) {
        $elementSections[$group["IBLOCK_ELEMENT_ID"]][] = $group["ID"];
    }

    $el = new CIBlockElement();
    foreach ($elementIds as $elId) {
        if (isset($elementSections[$elId]) && ($key = array_search($section_new, $elementSections[$elId])) !== false) {
            unset($elementSections[$elId][$key]);
            $el->Update($elId, ["IBLOCK_SECTION" => $elementSections[$elId]], false, false, true);
        }
    }
}
?>