For a few weeks now, my 99 Buick Park Avenue (just got it second hand), the “coolant low check coolant level” light has been on. I had some room in the reservoir to add coolant, but it was really quite full. A week or so later, I checked radiator, that too was basically full. The thermostat needle hits the halfway mark, but only because I’m keeping trips short. What is likely to be wrong and what will it cost to fix?
There’s a coolant level sensor in the coolant reservior. Most likely this level sensor is faulty indicating the coolant level is low when it’s actually not. This level sensor can be replaced by removing the reservior.