diff --git a/include/attsensor.h b/include/attsensor.h
index dc46e72..76055af 100644
--- a/include/attsensor.h
+++ b/include/attsensor.h
@@ -40,6 +40,9 @@ class AttSensor  {
     // Return the number of Bytes added to the Payload
     virtual uint8_t numBytes(void) = 0;
 
+    // Calibrate a Sensor. Needs to be Implemented in the Child Class if supported
+    void calibrate(void) {};
+
     // Helper Functions to Put Values Into the Payload Array
     static void int32ToPayload(int32_t value, char *payload, uint8_t startbyte) {
       payload[startbyte]   = (value) & 0XFF;
diff --git a/lib/MHZ19C/MHZ19C.cpp b/lib/MHZ19C/MHZ19C.cpp
index 00801ac..50d15b6 100644
--- a/lib/MHZ19C/MHZ19C.cpp
+++ b/lib/MHZ19C/MHZ19C.cpp
@@ -29,8 +29,15 @@
 
 // Constructor - Inititalize Hardware UART
 MHZ19C::MHZ19C(void) {
-    Serial.begin(9600);
-    Serial.setTimeout(MHZ19C_READ_TIMEOUT);
+  Serial.begin(9600);
+  Serial.setTimeout(MHZ19C_READ_TIMEOUT);
+}
+
+MHZ19C::MHZ19C(pin_size_t calpin) {
+  this->calpin = calpin;
+  
+  Serial.begin(9600);
+  Serial.setTimeout(MHZ19C_READ_TIMEOUT);
 }
 
 void MHZ19C::initialize(void) {
@@ -41,6 +48,14 @@ void MHZ19C::initialize(void) {
   #endif
 }
 
+void MHZ19C::calibrate(void) {
+  pinMode(calpin, OUTPUT);
+  digitalWrite(calpin, LOW);
+  delay(7500);
+  digitalWrite(calpin, HIGH);
+  pinMode(PIN_PB4, INPUT_PULLUP);
+}
+
 uint8_t MHZ19C::getSensorData(char * payload, uint8_t startbyte) {
     write(MHZ19C_CMD_GET_PPM, 0x00);
     delay(50);
diff --git a/lib/MHZ19C/MHZ19C.h b/lib/MHZ19C/MHZ19C.h
index 2250445..55c12b6 100644
--- a/lib/MHZ19C/MHZ19C.h
+++ b/lib/MHZ19C/MHZ19C.h
@@ -38,6 +38,7 @@
 class MHZ19C : public AttSensor {
   private:
     uint8_t buffer[MHZ19C_SER_BUF_LEN];
+    pin_size_t calpin = PIN_PB4; // PB4 is the Calibration Pin on the Addon PCB
 
     void write(byte cmd, byte arg);
     uint8_t read();
@@ -47,7 +48,9 @@ class MHZ19C : public AttSensor {
 
   public:
     MHZ19C(void);
+    MHZ19C(pin_size_t calpin);
     void initialize(void);
+    void calibrate(void);
     uint8_t numBytes(void) {return 2;};
     uint8_t getSensorData(char *payload, uint8_t startbyte);
     void setSelfCalibration(bool state);
diff --git a/src/main.cpp b/src/main.cpp
index a2ca9d3..76dcc83 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -364,17 +364,14 @@ void setup()
 void loop()
 {
   // Handle long Button Press for Calibration with MH-Z19C Sensor
-  #if defined HAS_MHZ19C && defined BTN_PIN
+  #ifdef BTN_PIN
   if  (digitalRead(BTN_PIN) == LOW) {
-    // Press Button longer than 4 Seconds -> Start MH-Z19C Calibration Routine
+    // Press Button longer than 4 Seconds -> Start Sensor Calibration Routine (if applicable)
     unsigned long loop_millis = millis();
     if ((unsigned long)(loop_millis - btn_millis) >= 4000) {
       WS2812B_SETLED(1,153,0,153);
-      pinMode(PIN_PB4, OUTPUT);
-      digitalWrite(PIN_PB4, LOW);
-      delay(7500);
-      digitalWrite(PIN_PB4, HIGH);
-      pinMode(PIN_PB4, INPUT_PULLUP);
+      for (uint8_t i=0; i<NUM_SENSORS; i++)
+        sensors[i]->calibrate();
       WS2812B_SETLED(1,0,0,0);
     } else {
       delay(500);
@@ -383,7 +380,7 @@ void loop()
   #endif
     // Only Run the LMIC loop here. Actual Sending Code is in do_send()
     os_runloop_once(); 
-  #if defined HAS_MHZ19C && defined BTN_PIN
+  #ifdef BTN_PIN
   }
   #endif
 }
\ No newline at end of file