E90 overheating - tested the water pump seems to be ok.

Hi Everyone



I am new to posting but have spent may hour researching how to maintain my 2003 Z4. Thank you for everyone that posts useful information.



I bought a 2006 323 about a month ago and have not had any problems with it. On the way home yesterday the yellow overheating water light came on shortly followed by the red. I pulled over and let the vehicle cool down and limped home.



I ran the diagnostic by checking the operation of the water pump by bleeding the system and the water pump seems to be working fine. The water pump failure seems to be the main problem that is mentioned.



I have read that the thermostat fails in the open position and that would result in the car running cold. I should also get a check engine light. Hence I do not think it is the thermostat.



When I started the car this morning to have a brief look at it, the cooling fan activated intermittently but not at full speed. I don't think there is a problem with the fan as it was running full speed when the car was overheating the day before.



Does anyone have any ideas as to why the car is overheating?

Is there a way to check the temperature sensor?



Thanks for your help.

E90 overheating - tested the water pump seems to be ok.