Within the past week, my Low Coolant Light has started to come on as soon as I start my '98 GP, and it stays on. After reading the following additional info, thanks in advance for any thoughts on why this might be happening.

Here's the additional info.

I got a new daily driver, so the car has been sitting a lot over the past 4 or so months.

I installed a new Optima Red Top battery within the past month.

I installed new radiator hoses, and serviced the cooling system within the past year.

No cooling system leaks, and the fluid level is fine.

This is a high mileage car, but I have maintained it very well.

No trouble codes are being thrown.

Thanks in advance for any ideas.