[WagonR]

I just had the same thing happen on my X3 (2013 3.5i). Light came on, then went off. I looked at the fluid level in the reservoir; it was below the min level, but there was still collant in there. I got my coolant from BMW, it was $8 for a quart. It's concentrated and you dilute 50/50 with distilled water. Ended up adding 2/3 of a quart, diluted, to get the level in the middle of high/low. At $8 I figured I may as well go with the same BMW fluid that was already in the system. As X4guy said, do it in the morning when everything's cold.

The car is 5 years old with about 60,000 miles. If the issue persists I will be concerned. However, if it was the accumulation of 5 years/60,000 miles, then I'm not overly worried about a small amount of coolant lost.