sgtloc

I discovered a quarter sized spot on my garage floor two days after purchasing my car last Nov. The SA on the phone said it was probably washer fluid as everything was topped off when I picked up car. Having been to this dance before, I blotted up the spot with a white towel and dipped the towel in coolant.
At the dealer after 2 1/2 hr wait thw SA said pressure test showed NO LEAK, I gave him the towel and he had a pow wow with manager, the result being new radiator, hoses and clamps. Everything replaced under original warranty.
I guess my point is there is no SLIGHT LEAK in a radiator , under pressure the coolant will exit very fast and serious engine damage will occur.

OP since they found your leak I would get it repaired before you drove too much further.

ImolaRedM

Many newer cars (not just BMWs) with the plastic radiators are more prone to leak.

That said, every BMW I have owned since a 1977 E12 all the way to my 2007 E60 have had the light come on each fall as the weather gets cooler. Top it off and you're set. If it happens again I would get the cooling system pressure checked. The coolant sensor is sensitive and unlike some other cars that I have owned, these sensors will tell you when you're low and not just when you're bone dry.

v_therussian

I've had some hoses replaced due to low coolant re-appearing several times regardless of my top-offs. This was last winter. The price that the dealer showed me was about a grand (a little less, actually), but it was under warranty. If it happened out of warranty, it'd probably be about 100+ for the replacement hose and maybe a couple of hours of getting grease on (and off) my elbows. A good indie mech IMHO should be able to pin-point a leak in a cooling system with his eyes closed. At the very least, those who claim to "specialize in foreign cars".

neoe60

I had this problem too. It turned out to be a radiator leak, dealer replaced under warranty.

tex_phil

I had it for 3 months, I found out it was the radiator return hose. I ordered the hose and sensor for about $90. I put it off for a long time, long time as in going thru 3 of the BMW coolant containers in that time frame. I wanted to take it to a shop because I couldn't reach the hose at the bottom. One day I said screaw it, I didn't want a shop to break something else. So I replaced it myself which took alot of effort and I no longer have the leak. It was leaking quite a bit but all is good now.

mrich1353

I had a similar warning earlier this year on my recently sold 2006 530XI. My message indicated low coolant and to service immediately. Ended up being the water pump. The car had about 60,000 miles and was under a certified warranty.