Php Regex介于文本之间不起作用

I´m getting data with

$newtext = fread($rcon, 102400);

But this script is not working

$offset = stripos($newtext, 'ÿ');

But if i print it i could see the y

EYî ÿ5aa68

Why is it not working? Its kind of wired.. Because .. It is there..^^

Thanks for your help and time :)

$answer .= preg_replace ('/(BE.*?)ÿ/' , '' , $newtext);

or if you only want to remove between codes:

$answer .= preg_replace ('/BE(.*?)ÿ/' , '' , $newtext);

You can play tested here (expand SUBSTITUTION TAB): http://regex101.com/r/tO1aB8/1