diff --git a/ampel-firmware/co2_sensor.cpp b/ampel-firmware/co2_sensor.cpp
index 6e0e01eb6102ccd60586a618fd38d73f726fa213..6fcf2f86863bbf6a726b90fa56aa1f7a1ab4e36b 100644
--- a/ampel-firmware/co2_sensor.cpp
+++ b/ampel-firmware/co2_sensor.cpp
@@ -30,21 +30,6 @@ namespace sensor {
   char timestamp[23];
   int16_t stable_measurements = 0;
 
-  /**
-   * Define sensor states
-   * BOOTUP -> initial state, until first >0 ppm values are returned
-   * READY -> sensor does output valid information (> 0 ppm) and no other condition takes place
-   * NEEDS_CALIBRATION -> sensor measurements are too low (< 250 ppm)
-   * PREPARE_CALIBRATION_UNSTABLE -> forced calibration was initiated, last measurements were too far apart
-   * PREPARE_CALIBRATION_STABLE -> forced calibration was initiated, last measurements were close to each others
-   */
-  enum state {
-    BOOTUP,
-    READY,
-    NEEDS_CALIBRATION,
-    PREPARE_CALIBRATION_UNSTABLE,
-    PREPARE_CALIBRATION_STABLE
-  };
   const char *state_names[] = {
       "BOOTUP",
       "READY",
diff --git a/ampel-firmware/co2_sensor.h b/ampel-firmware/co2_sensor.h
index d9eff8724f018e885f260060aaed58678c814092..eb2612ddefc5898c29c89062a5de812dab43bc6e 100644
--- a/ampel-firmware/co2_sensor.h
+++ b/ampel-firmware/co2_sensor.h
@@ -24,6 +24,24 @@ namespace sensor {
   extern float humidity;
   extern char timestamp[];
 
+  /**
+   * Define sensor states
+   * BOOTUP -> initial state, until first >0 ppm values are returned
+   * READY -> sensor does output valid information (> 0 ppm) and no other condition takes place
+   * NEEDS_CALIBRATION -> sensor measurements are too low (< 250 ppm)
+   * PREPARE_CALIBRATION_UNSTABLE -> forced calibration was initiated, last measurements were too far apart
+   * PREPARE_CALIBRATION_STABLE -> forced calibration was initiated, last measurements were close to each others
+   */
+  enum state {
+    BOOTUP,
+    READY,
+    NEEDS_CALIBRATION,
+    PREPARE_CALIBRATION_UNSTABLE,
+    PREPARE_CALIBRATION_STABLE
+  };
+
+  extern state current_state;
+
   void initialize();
   bool processData();
   void startCalibrationProcess();