I think I may need to replace my ECU. Radiator fan is constantly running in high mode soon as I start from cold. Have had the check coolant msg. I have replaced the coolant sensor on the expansion tank but still the same. Any suggestions welcome. Do I need to get fault codes read ? To make sure.

 

moved to W203 forum...

 

Have you checked the thermostat?

 

Hi. No as there appear to be a number of reasons for it. I've got a local Mercedes specialist so going to get my car hooked up on diagnosis machine to see what's going on. The engine temp is fine though. Rises normally when motor is running plus top and bottom radiator hose get hot as they should do.