$s2 -> array(4) { [0]=> string(7) "Renault" [1]=> string(4) "Opel" [2]=> string(8) "Mercedes" [3]=> string(4) "Audi" }


Error line:
Notice: Array to string conversion in C:


array(0) { }

//$dat_subcat_id = array();
	Error ->	  $dat_subcat_id = mysqli_query( $con,"SELECT * FROM subcategory  WHERE subcategory IN ('".$s2."') ")
                      or die( mysqli_error($con) );

					 $count2=0;
				$subcat_id = array();
				  while($row = $dat_subcat_id->fetch_array())
		 {

				$subcat_id[$count2]= $row['subcat_id'];

				$count2++;


				}
				var_dump($subcat_id);