[Benjt2]

Alright so I have a 2013 335i PWG, just recently my low coolant light came on, I had a flush early last year, so I checked and yeah its low, still some in res. But not a lot. Car is on a stage 2 custom tune.

How often do head gaskets fail? And Turbos? Idk where I'm losing coolant but I haven't found any leaks yet and the only thing I have noticed is my exhaust smells different then what i remember idk though. I don't know how to start diagnosing this and I want to before it gets worse and starts causing a lot more damage. Any help or insight will be greatly appreciated and I can give out as much info as needed.

Thanks to anyone who has anything to say!

[chowser51]

Did you try purging the system of possible air bubbles?

Did it go low again after you topped it off?

[BMWinAZ]

If your headgasket failed you should see the „milkshake" on your oil filler cap and also have a smokey exhaust. Check your oil filter housing gasket. I had a leaky one on the Mini and really didn't see much dripping while the engine was not running. On an F30 all the undercladding would easily mask the drips. The source of the leak only became apparent when my mechanic and I looked at the engine while it was running.

[BMWinAZ]

Another source of a low coolant light could come from running the heater for the first time after a coolant flush. If you or your shop don't run the heater right after refilling the coolant, turning the heat on for the first time a few weeks or months later, can cause low coolant levels due to the heater core siphoning off coolant. Happened to me a few years back in my old E83 X3.

[harmanonline85]

I have a 2013 328xi and i always get the low coolant warning in winters. I got it checked and there were no leaks and the coolant level was right upto the mark but still it shows low coolant warning on idrive. Sometimes it goes away after the car runs for a while but sometimes it stays there. Any suggestions/inputs?

[Billfitz]

It's probably a defective sensor, but to be sure you need to run a diagnostic to see what codes come up.

[harmanonline85]

Originally Posted by Billfitz

It's probably a defective sensor, but to be sure you need to run a diagnostic to see what codes come up.

I will get it checked this weekend. Thanks for your help!!

[harmanonline85]

Originally Posted by harmanonline85

I will get it checked this weekend. Thanks for your help!!

Update- Had to get my coolant expansion tank changed since the sensor was faulty...got it replaced and now no warnings😌😌

[cfm56d7b]

Originally Posted by harmanonline85

Update- Had to get my coolant expansion tank changed since the sensor was faulty...got it replaced and now no warnings😌😌

Replacing the faulty sensor is much less disruptive and less expensive than replacing the head gasket. Thanks for sharing the root cause.