thank you for your reply.
I've tested this and there is a brief Warning state before the Down, but this is by design and is a side effect of the Retry (SNMP Compatibility Option).
If you want the sensor to go down immediately (instead of retrying the query) head to the SNMP Compatibility Options settings group (in the settings of the parent device in PRTG) and configure:
SNMP Compatibility Options
|Failed Requests||Do not retry|
This should speed up the time it takes for the sensor to go down when the query fails (i.e. When it times out).
Luciano Lingnau [Paessler Support]