Strange readings from 4067 MUX

Hi Everyone,

Fairly new to Arduino, but have started a project to build a digital dashboard for my car.

I have added a 16 channel MUX to allow me to have more than 6 analog inputs on my uno.

Once I built the MUX I tested it reading the serial monitor and got the following readings, I can’t understand why there is a constant voltage to channels 8+. Surely this can’t be normal.

There is absolutely nothing plugged into the input side of the MUX so I would have hoped for every channel to show 0%.

Potentiometer at channel 0 is at 0.00%%
Potentiometer at channel 1 is at 0.00%%
Potentiometer at channel 2 is at 0.00%%
Potentiometer at channel 3 is at 0.00%%
Potentiometer at channel 4 is at 0.00%%
Potentiometer at channel 5 is at 0.00%%
Potentiometer at channel 6 is at 0.00%%
Potentiometer at channel 7 is at 0.00%%
Potentiometer at channel 8 is at 17.69%%
Potentiometer at channel 9 is at 18.18%%
Potentiometer at channel 10 is at 18.28%%
Potentiometer at channel 11 is at 18.18%%
Potentiometer at channel 12 is at 18.08%%
Potentiometer at channel 13 is at 18.28%%
Potentiometer at channel 14 is at 17.99%%
Potentiometer at channel 15 is at 18.08%%

What are peoples thoughts on this?

Thanks
Joe

(deleted)

Ahh excellent. Thank you.

I remember reading about this but I hadn't considered it.

Thanks for your help,