diff --git a/fw/Core/Inc/config.h b/fw/Core/Inc/config.h
index cb891da..c2d0f24 100644
--- a/fw/Core/Inc/config.h
+++ b/fw/Core/Inc/config.h
@@ -49,8 +49,8 @@ config_read(&config);
  * Device configuration data can be accessed using config_t struct.
  */
 #define CONFIG_DEFAULT_LED_ON					1
-#define CONFIG_DEFAULT_LED_ALERT1_LIMIT			1000
-#define CONFIG_DEFAULT_LED_ALERT2_LIMIT			2000
+#define CONFIG_DEFAULT_LED_ALERT1_LIMIT			1500
+#define CONFIG_DEFAULT_LED_ALERT2_LIMIT			3000
 
 #define	MODBUS_ADDR_LENGTH						2
 #define CONFIG_LED_ON_LENGTH					2
diff --git a/fw/Core/Src/main.c b/fw/Core/Src/main.c
index 532011e..79f6571 100644
--- a/fw/Core/Src/main.c
+++ b/fw/Core/Src/main.c
@@ -267,22 +267,15 @@ int main(void)
   MX_LPUART1_UART_Init();
   MX_TIM21_Init();
   /* USER CODE BEGIN 2 */
+
+  /* Turn on MAGENTA LED to signal startup state */
+  LL_GPIO_ResetOutputPin(LED_R_GPIO_Port, LED_R_Pin);
+  LL_GPIO_SetOutputPin(LED_G_GPIO_Port, LED_G_Pin);
+  LL_GPIO_ResetOutputPin(LED_B_GPIO_Port, LED_B_Pin);
+
   /* Enable I2C for sensors */
   LL_I2C_Enable(I2C1);
 
-  /* Enable UART for RS485 */
-  LL_LPUART_Enable(LPUART1);
-
-  /* Start the timer for measurement triggering */
-  LL_TIM_EnableCounter(TIM21);
-  LL_TIM_EnableIT_UPDATE(TIM21);
-  /*LL_TIM_GenerateEvent_UPDATE(TIM2);*/
-
-  /* I2C context init (for SHT4x and SCD4x) */
-  i2c_context_t i2c_context;
-  i2c_context.i2c = I2C1;
-  i2c_init(&i2c_context);
-
   /* Read config from EEPROM - if unsuccessful, set the default values*/
   int8_t config_read_status = config_read(&sensor_config);
   if (config_read_status != CONFIG_OK)
@@ -292,8 +285,22 @@ int main(void)
 	  sensor_config.led_co2_alert_limit2 = CONFIG_DEFAULT_LED_ALERT2_LIMIT;
 	  sensor_config.led_on = CONFIG_DEFAULT_LED_ON;
   }
+
+  /* Set the modbus address */
   modbus_slave_set_address(sensor_config.modbus_addr);
 
+  /* Enable UART for RS485 */
+  LL_LPUART_Enable(LPUART1);
+
+  /* Start the timer for measurement triggering */
+  LL_TIM_EnableCounter(TIM21);
+  LL_TIM_EnableIT_UPDATE(TIM21);
+
+  /* I2C context init (for SHT4x and SCD4x) */
+  i2c_context_t i2c_context;
+  i2c_context.i2c = I2C1;
+  i2c_init(&i2c_context);
+
   scd4x_start_periodic_measurement();
   uint8_t scd4x_is_connected = 1;
   uint8_t sps30_is_connected = 0;
@@ -321,8 +328,6 @@ int main(void)
   /* SPS30 Init Time: max 30000 ms 	(datasheet pg. 2) */
   LL_mDelay(1000);
 
-  /* Turn on LED to signal ready state */
-  LL_GPIO_ResetOutputPin(LED_B_GPIO_Port, LED_B_Pin);
 
   /* Enter the main loop */
   while (1)
@@ -347,12 +352,32 @@ int main(void)
 		  {
 			  sps30_read_measured_values(sps30_measured_data, 10);
 		  }
-
-		  /* Toggle LED for now */
-		  /* TODO: Remove LED Toggle */
-		  LL_GPIO_TogglePin(LED_B_GPIO_Port, LED_B_Pin);
-
 		  /* TODO: Process data and light a desired color of LED */
+		  /* TODO: Add hystheresis */
+
+		  if (CO2 <= sensor_config.led_co2_alert_limit1)
+		  {
+			  /* CO2 is OK -> BLUE */
+			  /* TODO: Decide if blue or green */
+			  LL_GPIO_SetOutputPin(LED_R_GPIO_Port, LED_R_Pin);
+			  LL_GPIO_SetOutputPin(LED_G_GPIO_Port, LED_G_Pin);
+			  LL_GPIO_ResetOutputPin(LED_B_GPIO_Port, LED_B_Pin);
+
+		  } else if ((sensor_config.led_co2_alert_limit1 < CO2) && (CO2 <= sensor_config.led_co2_alert_limit2))
+		  {
+			  /* CO2 is NOT OK -> YELLOW */
+			  LL_GPIO_ResetOutputPin(LED_R_GPIO_Port, LED_R_Pin);
+			  LL_GPIO_ResetOutputPin(LED_G_GPIO_Port, LED_G_Pin);
+			  LL_GPIO_SetOutputPin(LED_B_GPIO_Port, LED_B_Pin);
+
+		  } else if (sensor_config.led_co2_alert_limit2 < CO2)
+		  {
+			  /* CO2 is CRITICAL -> RED */
+			  LL_GPIO_ResetOutputPin(LED_R_GPIO_Port, LED_R_Pin);
+			  LL_GPIO_SetOutputPin(LED_G_GPIO_Port, LED_G_Pin);
+			  LL_GPIO_SetOutputPin(LED_B_GPIO_Port, LED_B_Pin);
+
+		  }
 
 		  /* Reset the TIM21 Elapsed Period Flag */
 		  tim21_elapsed_period = 0;