Please help - done a search - since yesterday morning been getting coolant level /temp warning on dash when first starting in the morning. Checked the levels looks ok - well above the max mark but I figure this is because it has expanded whilst heated. Same thing thing morning - goes away after a few minutes and is fine rest of the day even after a cool down. From searching is this the sensors being corroded/having muck stuck on them. How easy is it to get to the sensors? Just through the top of the coolant filler container? Any tips /advise would be much appreciated.