Oil alarm. Vesselview states low oil onboard tank HELP

[KramerSP]

2012 Mercury 250 Pro XS SN 1B917123. Had a low oil alarm go off. Filled remote tank to 3/4. Ran motor with cowling off and unscrewed onboard oil tank cap about 2 turns. Oil seeped out of tank while in the water and level (I didn't make a mess, had rags on hand). Still getting low oil fault with loud alarm and message on vesselview mobile stating onboard tank is critically low. Checked tank again and it is 100%full. Can it be the sensor on top of the tank or do I need to replace the whole tank? Code 714-21

[Tim619]

The sensors on those tanks are infamous for failing. Eventually they deteriorate and won't float any more. My understanding is that the tank assembly will need to be replaced if this is the case.

[JOE54]

complete tank replacement required

[Mackl]

Unfortunately I had the same issue recently. And have a new tank on order.

[Mackl]

On a 2014 Merc 250 Pro XS

[wmitch2]

When mine did that it was the sensor in the oil tank on the motor. It's built into the tank so you can't just replace the sensor, you have to do the whole tank.

[EuropeanAM]

As Joe suggested- Engine Mounted (Reserve) oil tank assembly will need to be replaced. The sensor itself seldom fails... but wise to replace both at the same time.