Coolant level sensor is located in the header tank, 202 have a known fault where an air pocket can develop around sensor float which causes the light to come on, you need to run eng up to opperating temp and then accelerate car suddenly 5-10 times to speed of 3500-4000 rpm, stop and turn off, open cooling system only when coolant is below 90 c remove cap slowly and reduce pressure, top up to top off filler neck (completly full) with eng warm, refit cap. Repeat procedure if necessary.