diff --git a/backend/internal/latest/faults.go b/backend/internal/latest/faults.go
index a7e6531..2cd0852 100644
--- a/backend/internal/latest/faults.go
+++ b/backend/internal/latest/faults.go
@@ -146,6 +146,12 @@ func sidecarDownSince(passes []store.LanePass, ok map[string]int64, cutoff int64
 			since = reached
 		}
 	}
+	// No Lane's retained pass log shows a sidecar reach: the honest age is
+	// the window itself — "at least twelve hours" — not the epoch, which
+	// humanAge would render as tens of thousands of days.
+	if since == 0 {
+		since = cutoff
+	}
 	return since, true
 }