Originally Posted by cesanche
I did the first time it overheated, but it really was below the min level. It was the 50/50 mixture, not the BMW coolant.
I looked again and I just don't see any leaks, so just wondering what could be setting off those codes.
I'm in the same boat. Coolant was a little low when I got the car back from a local guy walnut blasting and replacing the oil filter gasket. I added some Preston 50/50 that I've had on the shelf for a while and, about 100 miles later while cruising on the highway at 65mph, yellow to red to park on the shoulder. I let it cool off for about 5 minutes, started the car back up and all was good, no more temperature alarms. Drove it the 4 miles home and parked it. No leaks, no evidence of coolant splashing against anything I can see. I haven't driven the car or checked for codes since (been out of town for work) and was literally JUST about to order a new water pump and thermostat when you posted about a fluid difference.
Just speculation, but I wonder if a fluid flush and fill, all with the same type of fluid, would solve yours and my particular issues.
And, a little rant about how piss poor a design this is. A part that can cause catastrophic failure of the engine if not immediately diagnosed has no way to diagnose failure except with replacement and crossing ones fingers. Absolutely shameful.