Sensors are activated/deactivated according to asensor activation policy (SAP), which is a decision function whose domain is the language of the system. An SAP is minimal for diagnosability if it is at the point where the system is diagnosable, but any additional deactivation prevents correct system diagnosis. Given that the system is diagnosable when all sensors are always activated, we find in this paper that minimal SAP for diagnosability does not always exist. We therefore develop algorithms to compute a minimal SAP under which the system is pseudodiagnosable. Adhering to such a policy extends the window of opportunity for proper system diagnosis indefinitely, but with the compromise that later policy amendments are allowed.