Coolant System Warning Message (2nd try)

[brocca]

Hi there, it's me again. Still with the same problem. I have a W220 S430 1999 model and a "Coolant System - Visit Workshop" warning message appears on my console dash and the temperature climbs up as high as 100c. I've asked the forum for advice a while ago and was advised to check the Fan Unit, Water Pump & Thermostat. I've replaced all 3 units but the problem is still there. I suspect a faulty sensor - but which one and where? Would anyone know what it could be?
Thank you.
Bill

 

[andy@pcd-ltd]

Hi have you had the fault codes read

 

[television]

The water temp sensor is simple to fit and cheap and cheerful