diff --git a/examples/MQ-3/MQ4.ino b/examples/MQ-3/MQ-3.ino
similarity index 77%
rename from examples/MQ-3/MQ4.ino
rename to examples/MQ-3/MQ-3.ino
index 613a5a8..ef2b91b 100644
--- a/examples/MQ-3/MQ4.ino
+++ b/examples/MQ-3/MQ-3.ino
@@ -1,7 +1,7 @@
 /*
   MQUnifiedsensor Library - reading an MQ4
 
-  Demonstrates the use a MQ4 sensor.
+  Demonstrates the use a MQ3 sensor.
   Library originally added 01 may 2019
   by Miguel A Califa, Yersson Carrillo, Ghiordy Contreras, Mario Rodriguez
  
@@ -18,22 +18,22 @@
 
 //Definitions
 #define pin A0 //Analog input 0 of your arduino
-#define type 4 //MQ4
+#define type 3 //MQ3
 
 //Declare Sensor
 
-MQUnifiedsensor MQ4(pin, type);
+MQUnifiedsensor MQ3(pin, type);
 
 void setup() {
   //init the sensor
-  MQ4.inicializar(); 
+  MQ3.inicializar(); 
 }
 
 void loop() {
   //Read the sensor
-  int read =  MQ4.readSensor();
+  int read =  MQ3.readSensor();
   //Print measurements
-  Serial.print("MQ4: ");
+  Serial.print("MQ3: ");
   Serial.print(read);
   Serial.println(" PPM");
   //delay 1s to next measure