diff --git a/test/pid_zone_unittest.cpp b/test/pid_zone_unittest.cpp
index 47b3f97..ea8ac91 100644
--- a/test/pid_zone_unittest.cpp
+++ b/test/pid_zone_unittest.cpp
@@ -317,9 +317,15 @@
     zone->addPidFailSafePercent(input2, values[1]);
     zone->addPidFailSafePercent(input3, values[2]);
 
-    zone->markSensorMissing("temp1");
+    zone->markSensorMissing("temp1", "Sensor threshold asserted");
 
     EXPECT_EQ(failSafePercent, zone->getFailSafePercent());
+
+    std::map<std::string, std::pair<std::string, double>> failSensorList =
+        zone->getFailSafeSensors();
+    EXPECT_EQ(1, failSensorList.size());
+    EXPECT_EQ("Sensor threshold asserted", failSensorList["temp1"].first);
+    EXPECT_EQ(failSafePercent, failSensorList["temp1"].second);
 }
 
 TEST_F(PidZoneTest, GetFailSafePercent_MultiFailedReturnsExpected)
@@ -336,11 +342,21 @@
     zone->addPidFailSafePercent(input2, values[1]);
     zone->addPidFailSafePercent(input3, values[2]);
 
-    zone->markSensorMissing("temp1");
-    zone->markSensorMissing("temp2");
-    zone->markSensorMissing("temp3");
+    zone->markSensorMissing("temp1", "Sensor threshold asserted");
+    zone->markSensorMissing("temp2", "Sensor reading bad");
+    zone->markSensorMissing("temp3", "Sensor unavailable");
 
     EXPECT_EQ(80, zone->getFailSafePercent());
+
+    std::map<std::string, std::pair<std::string, double>> failSensorList =
+        zone->getFailSafeSensors();
+    EXPECT_EQ(3, failSensorList.size());
+    EXPECT_EQ("Sensor threshold asserted", failSensorList["temp1"].first);
+    EXPECT_EQ(60, failSensorList["temp1"].second);
+    EXPECT_EQ("Sensor reading bad", failSensorList["temp2"].first);
+    EXPECT_EQ(80, failSensorList["temp2"].second);
+    EXPECT_EQ("Sensor unavailable", failSensorList["temp3"].first);
+    EXPECT_EQ(70, failSensorList["temp3"].second);
 }
 
 TEST_F(PidZoneTest, ThermalInputs_FailsafeToValid_ReadsSensors)