Coolant system service light
 

Hello
im new to the forum I have a Volvo XC90 momentum 2016 model. The coolant system service light came on I took it to the dealer who replaced a sensor but a week late it came on again took it back to dealer who said it has two faults showing and they are not sure why so have now contacted Volvo for advice. I have only had the car a month and it is covered under Volvo selekt but does anyone know what causes this and is it a common fault on this model.