BMW 440i "Low Coolant" light

My BMW 440i has 27,000 miles on it. This morning, which was 25 F outside, the car gave the low coolant light. Topped the fluid off, and the rest of today it’s been fine. Checked under the car and found no leaked fluid and the car heats fine. What other things could have caused the low fluid light? Is it possibly weather-related? It’s Texas, so it rarely gets this cold, so I’ve been turning the heat up real high the past couple of days.
Likewise, it seems odd that a car this new (27,000 miles) should have a leak like this.
Any thoughts? Basically, I’m wondering if it sounds serious enough to drop off with dealership ($$$) or if I shouldn’t worry about it.

You bet! get this car to the dealer ASAP so you could use your warranty.

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As the coolant gets cold, it shrinks. That can cause the low coolant light to go on. Add a small amount and the light goes out. All is well. Next summer when it is 95 degrees the coolant expands and a litle bit dribbles out the overflow tube setting you up for a low coolant light next winter.

Had this exact issue with my Saab for most years. Never had another car do that. I blame it on a small air volume in a small overflow tank.

Have the dealer look at it. Enjoy coffee and snacks at the BMW dealer while you wait. Watch a little tv, relax.


Yes, get it to the dealer while it’s still under warranty.


At least take it to the dealer to get it documented. Even if they say no problem found, you will have a record in case something happens just after the warranty ends.

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That symptom would be unusual at 30K in most new cars, but some cars save engine compartment space (to make room for a turbo for example) by reducing the size of coolant system storage, and that might be an explanation for your 440i. Some coolant loss is normal, but it is usually on the order of a 1/2-1 cup or so in 30K miles. One cup low wouldn’t turn on a warning light on most vehicles. It’s possible the warning sensor is faulty also.

Coolant evaporates, I see vehicles with 20,000 to 30,000 miles with empty coolant reservoirs. The coolant should be topped off during each service visit but it seems that our lube techs are unaware of coolant reservoirs that are located under plastic panels.

When our X3 still under full warranty had this same issue (low coolant around 30K) we looked in the manual and it said to add in BMW coolant. We phoned the Boston-metro area dealer and asked them if we could bring it in and have them add it back. They said “Just add water.” The manual said “Do not add water.” We took it in and they added water as we watched. We got rid of the X3 and for that and other reasons switched brands. I’m sure you will be fine in Texas with any added liquid in the coolant tank, but you may want to peek at the manual for BMW’s recommendation.

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Really? A Boston-area BMW dealership shop suggested to add plain water to top off the cooling system reservoir?

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your overflow tank has a large surface area and water can easily evaporate. Top if off and keep watching the fill level.

I’m having a similar problem with my 2016 535i M Sport. I bought it in August 2019. In October 2019 the low coolant warning came on. I waited a week and it would go on and off throughout the week. I put coolant in myself then it went off. It went on again and I took it to the dealership. I live in NH. The low coolant warning has been going on and off since October. In December the ENTIRE ENGINE was replaced. I thought I’d never see that warning again. One week later it came on again. When they replaced the engine they found that an engine head bolt had been stripped and was essentially not doing anything - just floating there. Why then would the warning light come on again within a week? The dealership said they would take the car back but I have to repurchase from them and they can’t find a car I can afford that I like half as much as this one. Thoughts? Thank you!

Who is Jennifer?

They are doing you a favor . I can assure you that you don’t want to pay for a repair like this on a used BMW . Find something on that lot that seems to operate like it should and is not a European luxury vehicle . People with limited funds have no business with used vehicles like BMW, Volvo and Mercedes . After you get another vehicle start saving your money and then find a new vehicle with warranty.


Judgement about my life choices, aside I should have been clearer. I want to know why the warning light still came on after the engine was replaced under the CPO warranty. I can afford this car and other luxury cars of its ilk. I can’t afford a 2017 5 series for $48k.

It’s me. I’m new to this community and trying to find out why my low coolant warning won’t stop even after an engine replacement. Did it truly “burp” this time like they are saying?

And that is why so many vehicles like this are leased and then turned back in because of the expensive problems they can have.
As for your life style , that is your business but it is a simple fact that used European luxury vehicles can be large money pits.

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dealer paid for repair? They certainly do not replace a motor on a hunch. Now they need to do it again? Something sounds fishy. If this is a warranty repair, then I would go up a level and ask bmw why it’s so hard to fix things

Because the sensor for the warning light is not on the engine but in the coolant expansion tank, and they obviously have not changed that.

Thank you. The sensor is working correctly because it has been low in coolant. After the engine repair and about 300 more miles they say it came on again because it burped. Is that likely or are they missing something? I’ve just picked my car up today after 3 weeks without it. I’m waiting on them to find me a compatible replacement while I continue to use it but I’d genuinely like to slice this mystery!

Level went down after 3 weeks? So, they added more coolant. Now you can see if it continues to go down.