[kern417]

I think it has to be pretty low for the sensor to pick it up. Especially when the car is running and the coolant is expanded/constantly washing over the sensor.

My 440i was the same way. No warning and when I checked the tank it was damp but empty. I also had a similar issue with my X5 when the coolant tank started leaking. It didn't alert me until it was past empty.

[Araemo]

Originally Posted by kern417

I think it has to be pretty low for the sensor to pick it up. Especially when the car is running and the coolant is expanded/constantly washing over the sensor.

My 440i was the same way. No warning and when I checked the tank it was damp but empty. I also had a similar issue with my X5 when the coolant tank started leaking. It didn't alert me until it was past empty.

The sensor may be in the radiator or some other 'high point' of the cooling system besides the tank. However, that isn't reassuring.

[kern417]

Thanks for making me look that up. I don't see a single sensor on the realoem diagram, but I found another pic and my *assumption* is that the circled plug on the bottom should be the level sensor. I don't see anything on the smaller tank, which was the one that was dry on my car. The large tank was just low.

[Araemo]

Originally Posted by kern417

Thanks for making me look that up. I don't see a single sensor on the realoem diagram, but I found another pic and my *assumption* is that the circled plug on the bottom should be the level sensor. I don't see anything on the smaller tank, which was the one that was dry on my car. The large tank was just low.

I can 100% confirm there is no sensor for low coolant in the low-temperature loop (smaller tank is the reservoir for the low temperature loop, which circulates through the air/water intercooler and the AC hot side heat exchanger).

Mine was 100% dry due to a puncture in the front intercooler, and I had no indication of that until summer rolled around and my AC wouldn't work.

[kern417]

Originally Posted by Araemo

I can 100% confirm there is no sensor for low coolant in the low-temperature loop (smaller tank is the reservoir for the low temperature loop, which circulates through the air/water intercooler and the AC hot side heat exchanger).

Mine was 100% dry due to a puncture in the front intercooler, and I had no indication of that until summer rolled around and my AC wouldn't work.

Cool. That lines up with my issue as well. I guess since they decided it's not as critical to the engine and there are other sensors (IAT, etc.) that monitor it they don't need a level sensor.

[Araemo]

Originally Posted by kern417

Cool. That lines up with my issue as well. I guess since they decided it's not as critical to the engine and there are other sensors (IAT, etc.) that monitor it they don't need a level sensor.

It'd still be nice if there was some notice that it was out of spec. I have a suspicion when mine happened (December), and it wasn't noticed until the following spring (May-ish?), so I was probably running really high IATs for 6 months... though with the weather that year, 'really high' for the winter may not have been that high in the grand scheme of things. I would have been worried that the pump was damaged from running dry for so long, but they replaced the pump long before they found the leak, so it was moot.

[New Tari]

Its just normal to fill collant after certain period of time

[BLACK HAWK DOWN]

Originally Posted by New Tari

Its just normal to fill collant after certain period of time

No it is not.

[kaphouston]

I know this is a 3's and 4's thread BUT I thought I'd jump in here and let y'all know that my 2018 540i got the same low coolant message on Monday at 4200 miles. Have had the car 7 months. Had to add 24 oz (12 oz coolant/12 oz distilled water) to the larger reservoir. BOTH reservoirs were extremely low but only filled the larger one because the manual says ZERO about adding to the smaller intercooler. Took it to dealer today and left it with them. Where has 24 oz disappeared to? Why am I adding 24 oz at 4200 miles? There are other threads out there on this issue with '17/'18 G30's on another website. So I don't think this has to do with a specific model. I'm wondering if it's this B58 engine.

[G.Newt]

Originally Posted by kaphouston

I know this is a 3's and 4's thread BUT I thought I'd jump in here and let y'all know that my 2018 540i got the same low coolant message on Monday at 4200 miles. Have had the car 7 months. Had to add 24 oz (12 oz coolant/12 oz distilled water) to the larger reservoir. BOTH reservoirs were extremely low but only filled the larger one because the manual says ZERO about adding to the smaller intercooler. Took it to dealer today and left it with them. Where has 24 oz disappeared to? Why am I adding 24 oz at 4200 miles? There are other threads out there on this issue with '17/'18 G30's on another website. So I don't think this has to do with a specific model. I'm wondering if it's this B58 engine.

Most of us received the warning once, topped off, and haven't seen it since. The theory is that the coolant was under-filled from the factory. It is technically a "closed" system, not sure what that means as far as evaporation is concerned.

[B58togo]

Originally Posted by kaphouston

I know this is a 3's and 4's thread BUT I thought I'd jump in here and let y'all know that my 2018 540i got the same low coolant message on Monday at 4200 miles. Have had the car 7 months. Had to add 24 oz (12 oz coolant/12 oz distilled water) to the larger reservoir. BOTH reservoirs were extremely low but only filled the larger one because the manual says ZERO about adding to the smaller intercooler. Took it to dealer today and left it with them. Where has 24 oz disappeared to? Why am I adding 24 oz at 4200 miles? There are other threads out there on this issue with '17/'18 G30's on another website. So I don't think this has to do with a specific model. I'm wondering if it's this B58 engine.

Yes, it is the B58. Same cooling system in all models. My 240i also needed a total of 24 oz, but not until 19,550 miles. Now at just under 29k and have not gotten another warning.

[JimKden]

Originally Posted by G.Newt

Most of us received the warning once, topped off, and haven't seen it since. The theory is that the coolant was under-filled from the factory. It is technically a "closed" system, not sure what that means as far as evaporation is concerned.

yes, whenever the system is drained, the fill procedure calls for evacuating the air with a vacuum pump apparatus and bleeding in the coolant thru a 3 way valve. This is because the engine will not self bleed out the air. See the factory filling procedure that is, I believe, on this board. After operating a while the remaining air accumulates in the coolant tank. It needs to be topped off once or twice depending how quickly all the air ends up there. My car did the same thing not only new but when the air conditioning condenser was replaced because the radiator had to come out at that time.

[kern417]

Mine has definitely dropped. It was overfilled when I brought it in (over the max line), and now it is between the min and max line. I can also smell coolant sometimes when I'm driving. I'm waiting until spring to bring it in for eval.