diff --git a/firmware/core/peripheral.cpp b/firmware/core/peripheral.cpp
index 5147d69..e01ef80 100644
--- a/firmware/core/peripheral.cpp
+++ b/firmware/core/peripheral.cpp
@@ -48,8 +48,9 @@
         }
         break;
     case DoorPreparedOpen:
-        if (millis() - preparedTimer > DoorOpenTimeOut) {
+        if (millis() - preparedTimer > DoorPreparedOpenTimeOut) {
             digitalWrite(lockMagnetPin, HIGH);
+            openedTimer = millis();
             state = DoorOpened;
             Serial.println("DoorOpened");
             sendEventPacket(DoorDidOpen);
@@ -61,6 +62,18 @@
             state = DoorLocked;
             Serial.println("DoorLocked");
             sendEventPacket(DoorDidClose);
+        } else if(millis() - openedTimer > DoorOpenedTimeOut) {
+            Serial.println("DoorOpenTimedOut");
+            state = DoorOpenTimedOut;
+            return true;
+        }
+        break;
+    case DoorOpenTimedOut:
+        if (!detect()) {
+            digitalWrite(lockMagnetPin, HIGH);
+            state = DoorLocked;
+            Serial.println("DoorLocked");
+            sendEventPacket(DoorDidClose);
         }
         break;
     }
diff --git a/firmware/core/peripheral.h b/firmware/core/peripheral.h
index 18d9500..5d29c6b 100644
--- a/firmware/core/peripheral.h
+++ b/firmware/core/peripheral.h
@@ -9,16 +9,17 @@
 
 #define DetectorSwitchDelay 80
 #define LongPressThreshold 3000
-#define DoorOpenTimeOut  5000
+#define DoorPreparedOpenTimeOut  5000
+#define DoorOpenedTimeOut  20000
 
 class Door
 {
     enum DoorStateDef
     {
-        DoorLocked, DoorPreparedOpen, DoorOpened
+        DoorLocked, DoorPreparedOpen, DoorOpened, DoorOpenTimedOut
     };
     DoorStateDef state;
-    unsigned long preparedTimer;
+    unsigned long preparedTimer, openedTimer;
     unsigned long lastDectTime;
     unsigned char lastDectVal;
     bool detect(); //return true if lock detected door opened