diff --git a/firmware/heater_control.cpp b/firmware/heater_control.cpp
index b1f6689..2753cc5 100644
--- a/firmware/heater_control.cpp
+++ b/firmware/heater_control.cpp
@@ -117,12 +117,22 @@ HeaterState HeaterControllerBase::GetNextState(HeaterState currentState, HeaterA
             break;
         case HeaterState::ClosedLoop:
             // Check that the sensor's ESR is acceptable for normal operation
-            if (sensorTemp > overheatTemp)
+            if (sensorTemp <= overheatTemp)
+            {
+                m_overheatTimer.reset();
+            }
+
+            if (sensorTemp >= underheatTemp)
+            {
+                m_underheatTimer.reset();
+            }
+
+            if (m_overheatTimer.hasElapsedSec(0.5f))
             {
                 SetFault(ch, Fault::SensorOverheat);
                 return HeaterState::Stopped;
             }
-            else if (sensorTemp < underheatTemp)
+            else if (m_underheatTimer.hasElapsedSec(0.5f))
             {
                 SetFault(ch, Fault::SensorUnderheat);
                 return HeaterState::Stopped;
diff --git a/firmware/heater_control.h b/firmware/heater_control.h
index 02149a2..4b7a017 100644
--- a/firmware/heater_control.h
+++ b/firmware/heater_control.h
@@ -76,6 +76,12 @@ private:
     Timer m_preheatTimer;
     Timer m_warmupTimer;
 
+    // Stores the time since a non-over/underheat condition
+    // If the timer reaches a threshold, an over/underheat has
+    //    occured
+    Timer m_underheatTimer;
+    Timer m_overheatTimer;
+
     static const int batteryStabTimeCounter = HEATER_BATTERY_STAB_TIME / HEATER_CONTROL_PERIOD;
 };