diff --git a/source/Core/Threads/PIDThread.cpp b/source/Core/Threads/PIDThread.cpp
index b928692c..c7b27118 100644
--- a/source/Core/Threads/PIDThread.cpp
+++ b/source/Core/Threads/PIDThread.cpp
@@ -248,6 +248,11 @@ void detectThermalRunaway(const TemperatureType_t currentTipTempInC, const uint3
 
   static bool haveSeenDelta = false;
 
+  // Check for readings being pegged at the top of the ADC while the heater is off
+  if (!thisCycleIsHeating && (getTipRawTemp(0) > (0x7FFF - 16))) {
+    heaterThermalRunaway = true;
+  }
+
   if (haveSeenDelta) {
     return;
   }