Check_logfiles & 'NUL' characters


iam running into a problem where iam to stupid to solve it.
I have logfiles which should be monitored if a ‘NUL’ (hex x00) should not be found.

if i parse that logfile with

 # perl -ne '/\000/ and print;' /tmp/UDPLOG_Fr.TXT.crg
02.08.2019 00:00:53.157 #01 *** Paket: FG011315SD00K3AVBT1 00000000ANLZ005420190801235856720*r
02.08.2019 00:00:53.163 #01 *** Paket: FG011315AD00K3AVBT1 00000000ANLZ005420190801235856720*`
02.08.2019 00:00:55.003 #02 *** Paket: FG016172AD00F35110- 00000000ANLZ005420190802000054375*x

It show the lines with ‘NUL’ chararacters correctly, but no matter which pattern i use i dont get check_logfiles to report those lines.

Does anyone have an idea how to write a correct pattern for check_logfiles?