Hi Valen,
Thanks for the reply! Yes the ADDR pin is connected to GND (forgot to mention it). But the “-1” is still all that’s returned. I used a multimeter to check the pins. I’m getting 5V (VDD), 5V (SDA), 5V (SCL), and about 3V from V-divider to ads1115 pin A0. When I remove or apply voltage to that A0 pin, it still just keeps returning “-1”. So it’s like the Arduino just isn’t measuring anything and -1 is the code saying so. I also checked all jumper wired for continuity and all good there.