Aquamist HFS-3 and MINI Tank GB

[LASRGUY]

The button on the gauge should turn the gauge on. If you wired in the fail safe, it will give a CEL if the gauge isn't on. Probably a waste gate error. Once you get the gauge to turn on, you should set the WL pot full ccw and the WH pot full cw to avoid getting the CEL until you have time to go through the process of calibrating the low flow and high flow set points.