It turns out that I had had wires of the OBS3+ in the wrong screw terminals. Rewiring the high and low turbidity readings within a reasonable range. The problem now is that the sensor is not reading accurately. High turbidity always reads about 3 NTU and low turbidity always reads about 1 NTU. I have measured with two handheald turbidity meters and they were both reading 11-12 NTU. I checked and the grove cable is connected to the AA0-AA1 terminal and the aux analog port is switched from 3V – 5V. I’ve attached a photo of my wiring. Thanks!