[MONSTAR]

Hello -- just reaching 78k miles on my 2013 f30 328i (n26) and lately have received about 4 or 5 low coolant level warnings when starting my car.

Luckily, its usually when the car is cold so I turn off the engine and check the expansion tank to confirm that the coolant level is at the max line.

I've read the following posts already:

https://f30.bimmerpost.com/forums/sh...coolant+sensor

https://f30.bimmerpost.com/forums/sh...coolant+sensor

https://www.reddit.com/r/MechanicAdv...30_p143c_code/

https://www.bimmerfest.com/forums/sh...php?p=12737475

And have come to different conclusions. Some say that a new expansion tank is required. Some say that the sensor is built into the radiator and a new radiator+sensor is required. It doesn't seem that there's really ever any resolution posted anywhere.

The car appears to be operating normally. The oil temp gets up to 240ish or just under the 250 mark after sustained driving at 80mph on the freeway and quickly drops when coming to a stop.

Is it safe to continue driving and periodically checking the coolant level by eye?

Does anyone know if the sensor/radiator are needed or just the expansion tank....or all 3?

I will check tonight if I have any codes related to it.

Thank you

[kern417]

If the coolant isn't actually low, then it's safe to drive. I'd guess you need to replace the coolant level sensor, which is integrated into the reservoir (see the plug at the bottom).

PN: 17137642158

[MONSTAR]

Originally Posted by kern417

If the coolant isn't actually low, then it's safe to drive. I'd guess you need to replace the coolant level sensor, which is integrated into the reservoir (see the plug at the bottom).

PN: 17137642158

Thanks bud! I'll order that now and keep checking the level. I'm planning a maintenance day soon with an oil change, plug change, air filter clean, etc. so I'll probably do it then.

[Rayzor]

I am having the same issue with my f30 335i, ran the bleed test and the waterpump is working as it should. I am going to try and do a coolant flush and as a last resort replace the expansion tank. If you resolve the issue, please update the thread.

[MONSTAR]

Originally Posted by Rayzor

I am having the same issue with my f30 335i, ran the bleed test and the waterpump is working as it should. I am going to try and do a coolant flush and as a last resort replace the expansion tank. If you resolve the issue, please update the thread.

Sure man, I'll keep it in mind. I think its a good opportunity for me to switch to redline water wetter and distilled water

[Blemus2061]

Don't forget to make sure you don't have corrosion in the connector for coolant level sensor in the expansion tank. Sometimes leaks through connectors and corrodes the harness and needs to get replaced. There's a repair kit from bmw for that as well

[MacsRule]

Originally Posted by MONSTAR

Hello -- just reaching 78k miles on my 2013 f30 328i (n26) and lately have received about 4 or 5 low coolant level warnings when starting my car.

Luckily, its usually when the car is cold so I turn off the engine and check the expansion tank to confirm that the coolant level is at the max line.

I've read the following posts already:

https://f30.bimmerpost.com/forums/sh...coolant+sensor

https://f30.bimmerpost.com/forums/sh...coolant+sensor

https://www.reddit.com/r/MechanicAdv...30_p143c_code/

https://www.bimmerfest.com/forums/sh...php?p=12737475

And have come to different conclusions. Some say that a new expansion tank is required. Some say that the sensor is built into the radiator and a new radiator+sensor is required. It doesn't seem that there's really ever any resolution posted anywhere.

The car appears to be operating normally. The oil temp gets up to 240ish or just under the 250 mark after sustained driving at 80mph on the freeway and quickly drops when coming to a stop.

Is it safe to continue driving and periodically checking the coolant level by eye?

Does anyone know if the sensor/radiator are needed or just the expansion tank....or all 3?

I will check tonight if I have any codes related to it.

Thank you

For what it's worth, I got the same low coolant alerts and it ended up being the oil filter housing. The gasket failure was causing the coolant and oil to slowly leak. Make sure you check the filter housing and surrounding area before making a more costly repair.

[MONSTAR]

Originally Posted by Rayzor

I am having the same issue with my f30 335i, ran the bleed test and the waterpump is working as it should. I am going to try and do a coolant flush and as a last resort replace the expansion tank. If you resolve the issue, please update the thread.

Just wanted to update that I hadn’t pulled the trigger on ordering a replacement expansion tank yet. It’s been 2 weeks and I stopped getting the low coolant level warnings. I was checking daily before my commute to work and the level has been at the max line since this started.

It may have been caused by our fluctuating weather here in SoCal but I’m not sure. I will definitely update if the warning comes back and if I go through with diagnosing/replacing

[mechatony11]

I apologize for bringing up this old thread. I had a similar issue with my vehicle recently; the radiator coolant was mysteriously getting low. As I further checked the hoses, cracks in the radiator, or head gasket, there was no sign of leakage. It turned out that my radiator cap was damaged and it’s not holding the standard operating pressure anymore, so I immediately replaced it. I came across an in-depth article that may be worth reading. Search for "Mercedes-Benz Check Coolant Level Warning Light on YOUCANIC" and you will see an article that goes over common causes and possible fixes. You can read about it yourself. I hope this information can assist someone else with a similar issue.