Hello, I found a libary on the Internet for the IAQ wich does not works its stopping at the
Wire.endTransmission(); When I am removing the SCL the program goes on.
Its in the IAQcore.cpp at line 172
I am using this libary GitHub - hafu/IAQCore: Arduino library for iAQ-core indoor air quality sensors also using the Example. I am having the IAQ Core P
The Arduino Wire library halts at Wire.endTransmission() when the SCL or SDA are shortcut to GND or shortcut to each other. Try to fix your I2C bus.
To test your I2C bus, use a I2C Scanner sketch.
The "iAQ-Core P" is a 3.3V sensor. When you are using a Arduino Uno, then you have a 5V Arduino board. If so, how did you connect a 3.3V sensor to a 5V board ? A 5V Arduino board can lift the SDA and SCL signals above 3.3V because the internal pullup resistors are enabled in the Wire library. Your sensor might already have been damaged.
The Arduino IDE is now at version 1.8.11, and it is still possible that an external event can halt a sketch with the Arduino Wire library for AVR microcontrollers. That should have never happened. In my opinion it means that the Arduino software is still not ready to be released.