low salt indicator light “stuck” on

Dishwasher model: Ikea/Whirlpool DWH M10 W

The controls are in the top edge of the door (so are concealed while the machine is in use). There are five green lights along the top, each indicating a different wash program, plus two red lights – one to indicate low rinse aid and one to indicate low salt.

I’ve had this dishwasher a little over a month and it’s working just fine so far except for one small annoyance: after about a week of using it, the low salt indicator light came on and won’t go off again, even though the salt level is most definitely not low.

Any thoughts? Is it likely to be something serious that needs looking at?

d.