Can clarify please how can I know if my Pi's SDA ou SCL GPIO are bust or are not in the correct mode? I used to work with my pcf8951 but I have the same problem I couldn't detect the address of my device and the red led is on , how to know also if it is the converter that is broken ?

for my dashboard I developed a Qt application. the complete system reads the signal from all the sensors and output the result on a GUI application on the screen. When the engine is running the signal that are coming from light, Gear, fuel level and are connected to the GPIO pins that are not configured as interrupt works normally only the one GPIO that is configured as an interrupt is causing the problem and it is detecting noise. This seems so weird to me ! why is the problem comes only when configuring the pin as interrupt

I just edited my post sorry for my english, hope it is clear now. It has been like 2 months that I am facing this problem. this is my post on electrical engineering forum electronics.electronics.stackexchange.com/questions/571035/… First I though it is because of how I was doing the conditioning of my sensor but when starting to locate the problem i found out that the GPIO is detecting noise even if the sensor if not connected ! just having a wire that connectes a pull up from the GPIO to 3.3v causes problem

to locate the problem, I am just powering the Pi with the official supply power, I didn't even connect the output of the sensor or any thing to the GPIO of the Pi , the pi is just connected to the official power supply, a micro HDMI and a USB for the screen and nothing else, nothing is connected to any GPIO. when running the engine nothing will be detected but just by adding simply an external pull up it starts detecting noise :(