[Foxlovescars]

Hey guys:
Out on the road tonight away from home and my cluster says "Low Coolant." I know where it goes and how to get to it. My question is: can I add Prestone 50/50 to my blue European fluid? At a convenience store on the Interstate and need a quick answer!
Thanks in advance,
Frank from Florida

[Coastali8]

Don’t ignore the warning. Don’t add non BMW approved coolant. Don’t open the expansion tank. (You can take a look and see if the coolant is actually low and if it’s maybe just a sensor failure just by looking at the semi transparent expansion tank) Take it to the BMW dealer for repair.

[MolarBear]

Very likely a sensor issue not coolant. Get someone to help you open the bonnet. Check the coolant is in the middle of the container and not below. If so it's a faulty sensor. Book in to the dealer to get the sensor checked - I'm taking mine in on Thursday. The light will go on once a week currently.

[MGRMLN]

As is previously mentioned, the coolant tank on i8's are located below the highest point of the ICE engine. This means the entire system needs to be pressurized in order for the coolant to reach the uppermost part of the motor. If you open the coolant reservoir, you will introduce bubbles in the coolant causing areas of the motor to overheat, leading to catastrophic results. Go to the dealer or a qualified shop that has pressurized coolant gear, like shops that work on water cooled Porsches. They have a similar system I'm told.

If you open the front, and the reservoir bottle is at half or above, you have a bad sensor. It is built into the tank itself so the entire thing will need to be replaced. My 2015 had this issue.

[Foxlovescars]

Thanks for the great posts.

Didn't get a quick a quick-enough answer last night on the road so just left things alone. When I got home last night I lifted the hood and saw two reservoir tanks; the square one under the front windshield and the round one closer to the fan. I DID take the cap off of the round one.

Attached is a diagram of what I am referring to. The round one (part #12) IS the reservoir, correct? If in fact, the system is not pressurized and I screwed up, should I drive to the dealership or have it flat-bedded there to replace the sensor?
Thanks again for the educated responses.
Frank

[Coastali8]

Yes the round one #12 is the high temp coolant reservoir.

If the reservoir is empty or significantly below the fill line you have a leak somewhere and need to take the car to the dealership. Flatbed is probably a good idea unless you can get there on electric as you don’t want to overheat the gas engine. If the tank is empty you can’t just fill the tank because you will have air that will be trapped in the system.

If the tank is just a tiny bit below the fill line I would add BMW approved coolant or distilled water up to the full line on the reservoir and see if that extinguished the low coolant warning. Your car is 6 years old and could be a small amount of coolant was lost to evaporation.

If the coolant is still at the full level on the tank then you probably just have a sensor issue and could drive the car to the dealership for repair.

[Foxlovescars]

The fluid level is just above half-full and I don't see a mark anywhere on the bowl showing the fill level. Any thoughts?
Thanks,
Frank

[Coastali8]

Yes,
My thoughts are it’s just a sensor issue.
Take the car to the dealership for repair.

[Foxlovescars]

Thanks everyone for the information. There is also a very informative video from Pat on Youtube concerning the fix. I ordered the coolant reservoir from BMW of Atlanta and will have my local BMW dealer install it, cut and re-solder the wiring (where the fluid tends to leak down into) and re-pressure the whole system.
Thanks again,
Frank

[MolarBear]

Did they definitely diagnose that as a fault? It was just a software update for me!

[mwhfgjvcg]

Issue was solved after software update.