This question is an exact duplicate of:
Arduino Uno user here
I am building a project with 4 analog inputs A0 dose not work. A1 A2 and A3 work perfectly fine! But for last input when I connect to A4 or A5, then they do not go to zero. They are stuck between 400 to 900. Even when connected to arduino ground it gives 400 instead of 0.
Am I missing something here cause the circuit for A4 connected to A3 gives perfect input value. They both work fine as output. Same situation with A5.
Is there another way to get one more Analog Input without multiplex?