diff --git a/ampel-firmware/ampel-firmware.ino b/ampel-firmware/ampel-firmware.ino
index 9e2ee0c5ded00bb8a85163b5ecc577cac4d323f5..c5e82c868a13ce2eca3fd5365e9364c903a50d52 100644
--- a/ampel-firmware/ampel-firmware.ino
+++ b/ampel-firmware/ampel-firmware.ino
@@ -78,7 +78,7 @@ void setup() {
 #ifdef AMPEL_WIFI
   WiFiConnect(SENSOR_ID);
 
-  Serial.print(F("WiFi STATUS: "));
+  Serial.print(F("WiFi - Status: "));
   Serial.println(WiFi.status());
 
   if (WiFi.status() == WL_CONNECTED) {
@@ -150,7 +150,7 @@ void loop() {
   uint32_t duration = millis() - t0;
   if (duration > max_loop_duration) {
     max_loop_duration = duration;
-    Serial.print("Max loop duration : ");
+    Serial.print(F("Debug - Max loop duration : "));
     Serial.print(max_loop_duration);
     Serial.println(" ms.");
   }
diff --git a/ampel-firmware/co2_sensor.cpp b/ampel-firmware/co2_sensor.cpp
index e9c40c79c322383bd9f771203e33ef7abc02b14a..7110776f7ab9362e431917afa8ebc84cd8bcb653 100644
--- a/ampel-firmware/co2_sensor.cpp
+++ b/ampel-firmware/co2_sensor.cpp
@@ -116,8 +116,8 @@ namespace sensor {
   }
 
   void logToSerial() {
-    Serial.println(timestamp);
-    Serial.print(F("co2(ppm): "));
+    Serial.print(timestamp);
+    Serial.print(F(" - co2(ppm): "));
     Serial.print(co2);
     Serial.print(F(" temp(C): "));
     Serial.print(temperature, 1);
diff --git a/ampel-firmware/csv_writer.cpp b/ampel-firmware/csv_writer.cpp
index 26c0b00e11a8146188521829758cef84333efe3b..653630335527800481fb4907025e494e2de3fd58 100644
--- a/ampel-firmware/csv_writer.cpp
+++ b/ampel-firmware/csv_writer.cpp
@@ -115,11 +115,7 @@ namespace csv_writer {
     // Open dir folder
     Serial.println("Filesystem content:");
     showFilesystemContent();
-
-    if (FS_LIB.exists(filename)) {
-      Serial.print(filename);
-      Serial.println(" has been found.");
-    }
+    Serial.println();
   }
 
   File openOrCreate() {
@@ -145,7 +141,7 @@ namespace csv_writer {
       if (written_bytes == 0) {
         Serial.println(F("Nothing written. Disk full?"));
       } else {
-        Serial.println(F("Wrote file content:"));
+        Serial.print(F("CSV - Wrote : "));
         Serial.print(csv_line);
         last_successful_write = ntp::getLocalTime();
       }
diff --git a/ampel-firmware/lorawan.cpp b/ampel-firmware/lorawan.cpp
index 6d86c8a15ea81ac5a0d6b3c36a21a3f8795f0d22..7e027703ebd6505577005de734c3272beb785789 100644
--- a/ampel-firmware/lorawan.cpp
+++ b/ampel-firmware/lorawan.cpp
@@ -82,18 +82,18 @@ namespace lorawan {
         u1_t nwkKey[16];
         u1_t artKey[16];
         LMIC_getSessionKeys(&netid, &devaddr, nwkKey, artKey);
-        Serial.print(F("netid: "));
+        Serial.print(F("  netid: "));
         Serial.println(netid, DEC);
-        Serial.print(F("devaddr: "));
+        Serial.print(F("  devaddr: "));
         Serial.println(devaddr, HEX);
-        Serial.print(F("AppSKey: "));
+        Serial.print(F("  AppSKey: "));
         for (size_t i = 0; i < sizeof(artKey); ++i) {
           if (i != 0)
             Serial.print("-");
           printHex2(artKey[i]);
         }
-        Serial.println("");
-        Serial.print("NwkSKey: ");
+        Serial.println();
+        Serial.print("  NwkSKey: ");
         for (size_t i = 0; i < sizeof(nwkKey); ++i) {
           if (i != 0)
             Serial.print("-");
diff --git a/ampel-firmware/mqtt.cpp b/ampel-firmware/mqtt.cpp
index 4f189bb35c69e0b2385ce2be1b54e98eb3098446..ebb4ad24182c9eeec721c44ca59e892c7056a54c 100644
--- a/ampel-firmware/mqtt.cpp
+++ b/ampel-firmware/mqtt.cpp
@@ -41,7 +41,7 @@ namespace mqtt {
   void publish(const String &timestamp, int16_t co2, float temperature, float humidity) {
     if (WiFi.status() == WL_CONNECTED && mqttClient.connected()) {
       led_effects::onBoardLEDOn();
-      Serial.print(F("Publishing MQTT message ... "));
+      Serial.print(F("MQTT - Publishing message ... "));
 
       char payload[75]; // Should be enough for json...
       snprintf(payload, sizeof(payload), json_sensor_format, timestamp.c_str(), co2, temperature, humidity);
@@ -185,7 +185,7 @@ namespace mqtt {
       // No WIFI
       return;
     }
-    Serial.print(F("Attempting MQTT connection..."));
+    Serial.print(F("MQTT - Attempting connection..."));
 
     led_effects::onBoardLEDOn();
     // Wait for connection, at most 15s (default)
diff --git a/ampel-firmware/wifi_util.cpp b/ampel-firmware/wifi_util.cpp
index 60fd8fa691c98a0db45c33aff73caff0194cf496..dc496293345f5b3f743e6ed369d5e792376514d9 100644
--- a/ampel-firmware/wifi_util.cpp
+++ b/ampel-firmware/wifi_util.cpp
@@ -23,7 +23,7 @@ void WiFiConnect(const String &hostname) {
   WiFi.setHostname(hostname.c_str());
 #endif
 
-  Serial.print("\nConnecting to ");
+  Serial.print(F("WiFi - Connecting to "));
   Serial.println(config::wifi_ssid);
   WiFi.begin(config::wifi_ssid, config::wifi_password);
 
@@ -35,11 +35,11 @@ void WiFiConnect(const String &hostname) {
   if (WiFi.status() == WL_CONNECTED) {
     led_effects::showKITTWheel(color::green);
     Serial.println();
-    Serial.print("\nWiFi connected, IP address: ");
+    Serial.print(F("WiFi - Connected! IP address: "));
     Serial.println(WiFi.localIP());
   } else {
     //TODO: Allow sensor to work as an Access Point, in order to define SSID & password?
     led_effects::showKITTWheel(color::red);
-    Serial.println("\nConnection to WiFi failed");
+    Serial.println(F("Connection to WiFi failed"));
   }
 }