over heat msg

[yarayal]

I have a small puzzle for you ... its about my 2007 bmw 530i

i was driving at a speed of 140km/h and suddenly a msg poped up saying "engine over heated, STOP immediately", i pulled over checked the car for any leaks but all appeared in good shape. at the same time another msg saying "low battery poped up".

the recovery came and took the car to the dealer, i didn't mention the over heating and only told them the battery needs replacing as i read on the net that low batter power can cause the car to show funny msgs like ABS or traction's control or airbag problems and sometimes over heat problems.
anyways they changed the battery, and told me that they saw on the log of the car that there was a over heat msg, they kept the car running for sometime it looks fine, but they also mentioned that normally if the car is under warranty they will change the water pump just in case. but since the warranty is over they asked me to drive the car and if the same msg pops out then ill need to change the water pump.

months passed and i drove over 1000km all looked good, then suddenly the same msg appeared, now the funny and weird thing is that once i pull over and check the coolent sub tank, it all looks good .. fan working properly water levels are normal. i start the engine and the msg is gone !!!!
now.... i drive over 200km sometimes 500km then only the msg will pop up... stop the engine and immediately start back, the msg is gone !!!






what do you think ?