Which timer expiration can lead to an EIGRP route becoming stuck in active?

Explanation:
As noted above, when a route goes into the active state, the router queries its neighbors to find a
path to the pertinent network. At this point, the router starts a three minute active timer by which
time it must receive replies from all queried neighbors. If a neighbor has feasible successors for
the route, it will recalculate its own local distance to the network and report this back. However, if a neighbor does not have a feasible successor, it also goes into active state. In some cases,
multiple routers along multiple query paths will go into active state as routers continue to query for
the desired route. In most cases, this process will yield responses from all queried routers and the
sought after route will transition back into the passive state within the three minute SIA query
timer. In the case that none of the queried routers can provide a feasible successor, the route is
cleared.
In some cases, a response is not received between two neighbor routers because of link failures,
congestion or some other adverse condition in either the network or on the queried router, and the
three minute active timer expires on the router originating the query. When this happens, the
querying router that did not receive a response logs a “DUAL-3-SIA” or “stuck-in-active” error for
the route and then drops and restarts its adjacency with the non-responding router
Reference. http://www.packetdesign.com/resources/technical-briefs/diagnosing-eigrp-stuck-active