On my 2005 325ci 2.5L 35k miles I sometimes get a intermittent “check coolant” warning light on my dashboard. I use only OEM BMW Coolant and when I top it off the light goes off but sometimes returns from time to time. It does not stay on. My code reader shows no present faults. Coolant system is flushed professionally every 6 months or so. I know others have this problem in my research. Everything seems to be pointing at a possible faulty sensor?
Any ideas and service advise?
Hello Mr. Vizzusi, a scan tool without BMW software will not be much help in this case, with the BMW software you can see the signal from the sensor to the control unit. The failure you are describing is fairly common on the E46 cars, the likely culprit is the coolant level sensor. I would have a coolant pressure test done on the system just to make sure that you do not have any small leaks, the other issue can be air trapped in the cooling system, to ensure that there is no air in the system: drive the vehicle with the heat on high fan speed and the airflow to defrost until the engine is at operating temperature, this usually takes about 20-30 minutes. If you have full hot air coming from the defrost vent for 5 minutes you are ok. Please let me know if you have any other questions. Good luck. Thank you..