This is still not correct, here you sould set the name of your temperature sensor i.e. “Chassis”. This will replace the %s in service_name = "Temperatur %s". If you do not need a name for your temp sensor, remove the %s in service_name and the item="Temperature %s" in the discover function. Also remove then the parameter item form the check function.
For the detect function. Looks like this works. From the cmk -vvII RPz
SNMP scan found hr_mem rzp snmp_info snmp_os snmp_uptime
Here you can see the plugins CMK has found.
Can you do the cmk -vvII with the --debug option please (cmk --debug -vvII RZp) and an snmpwalk on the cli over the OID .1.3.6.1.3.1.0.