Firstly..
"Four functions of the coolant warning light:
1. Engine coolant level too low -- light flashes slowly (0.5 Hz)
2. Engine compartment temperature too high -- light flashes slowly (0.5 Hz) (engine compartment blower might be faulty )
3. Engine coolant temperature too high -- light is lit; pointer on the right
4. Temperature sensor at water outlet faulty -- light flashes rapidly (1 Hz) ; pointer on the right
Note: The temperature warning in point three is indicated if the conditions "engine coolant temperature too high" and "engine coolant level too low" are present simultaneously."
Secondly
Check the coolant level, add if necessary - coolant caps ending in part number 00 are prone to failure, you need one ending 01 as a minimum. Check expansion tank for leaks / splits too. If its split then normally the coolant runs out via the rear boot floor and exits inboard of the offside rear wheel.