Fluid Sensor issue (Error 1014)

Your float test was the right instinct, but moving under a finger is not the test. The float has two separate jobs: move freely, and carry its magnet close enough to the reader. Either one failing gives the same low-water error.

1. Does it actually float? Fill the tank, invert it slowly, watch the float rise on its own. If it pivots when poked but sits low or sinks, the float is the fault. Usually a hairline crack letting water in, or scale on the guide pin.

2. Is the magnet still there and still aligned? Tank out, run a small fridge magnet along the outside of the tank where the float sits. You should feel a pull through the plastic. No pull where you can feel the float means the magnet has come loose inside the float, and that tank is done.

3. Test the robot side with the tank out. Machine on, hold a fridge magnet against the reader area in the tank bay for a few seconds. If the warning clears, the reader is fine and the tank is the problem. If nothing changes at all, the reader or its wiring is the problem.

4. The reader sits in the tank bay on the Combo models, not inside the tank, and it is board-mounted. No field replacement. If step 3 points there, check the contact pads and the ribbon at the bay for corrosion or a cracked solder joint first, then it is iRobot support or a board-level repair.

One caution: warm water agitation is the right move, but never hotter than warm, and rinse with distilled if your water is hard. Scale film on the guide pin will bind the float again within a week.

Most of these end at step 2 or 3, and the cheap fix is a replacement tank rather than a robot. Do the two magnet tests before spending on either, because they are the only thing that tells you which part is wrong.