'04 330i, 105k miles. Coolant light comes on once car is warmed up and at speed. Usually goes out after a minute or two of idling, then comes on again at speed. The most recent cooling system work was a new water pump about 3 months/4k miles ago...topped system up with BMW coolant mix then, no problems until now. Coolant level is fine. Temp gauge is normal. Replaced ET cap (cheap shot in the dark), but same results. Anyone experienced similar problem? Any ideas? Thanks!