Coolant Level Warning Light 1.8 SRI manual 2013 55000 miler

Had the light come on for no reason last week,the levels bang on so lost no coolant.

Changed the level sensor with a genuine OE one off a Vauxhall de3aler on Ebay and it still randomly comes on,normally on start up then when it feels like it.

I've read about some Astra recalls online but no Insignias.

Any cures anyone please?