BMW's low coolant warning typically comes on due to the low coolant level in the engine bay's expansion tank.
Checking the coolant level on a BMW is easy and takes less than five minutes. It is crucial to follow the correct procedure to avoid injuries and get an accurate reading.
- Engine coolant level light on
- Message on iDrive stating Low engine coolant level
- Engine Overheats
- Coolant warning on, then off after driving
- Engine coolant level too low
- Risk of engine damage! Top up the coolant at the earliest opportunity; see the owner's handbook. Caution: Risk of scalding!
How to Check BMW Engine Coolant Level
Follow these easy steps to check the coolant level on any BMW.
For this procedure, you will need OEM BMW Engine Coolant recommended in your owner's manual and mixed at 50/50.
- Park your BMW in a safe location and set the parking brakes.
- Allow the engine to cool down. Make sure the engine is cooled down before you remove the cap from your coolant reservoir or risk getting burned.
- Open the hood. Pull the hood release under the dash twice.
- Locate the coolant expansion tank in the engine bay. As you open the hood, look at the left of the engine bay. This is the typical coolant expansion reservoir location. Some BMW models, such as the 3-series, have the coolant expansion reservoir on the engine bay's right side.
Remove the coolant reservoir cap. Turn it slowly counterclockwise. It will allow residual pressure to release without blowing off the cap.
Determine the coolant fluid level. There are two different float designs. The red float may have two balls, indicating the low and the second indicating the full level. The level is full when the bottom of the float reaches flush with the top of the cap.
- Add OEM BMW Engine Coolant mixed at 50/50. If the float is all the way down, you need to add coolant. If the float is sticking up, your BMW coolant level is full. In other words, the BMW coolant level is correct if the red float is aligned with the top edge of the filler opening. A schematic diagram stamped on top of the coolant reservoir, illustrating the min and max level. Rember, the level reading should be performed on a cooled down the engine for proper measurement.
- Only use the BMW OEM engine coolant (PN: 82141467704) or a coolant that meets the requirements listed in your owner's manual. BMWs have specific coolant requirements to prevent build-up and corrosion of aluminum components, therefore do not use off-the-shelf antifreeze without checking compatibility.
- The cap may not be holding the pressure and could be leaking coolant. Replace the cap. Also, clean the cap as there can be a buildup of solids, not allowing the rubber to seal the system and cause a leak.
- Typically, you don't need to add more than one quart/liter to top off the system. To make the float move from the minimum level to the maxim, you need less than a quart of coolant.
- If you have to add more than one quart, you may have a coolant leak. If you are constantly adding coolant to your BMW or have to add more than one gallon of antifreeze, you may have a major coolant leak or a serious engine problem such as a blown head gasket.
- BMW uses a closed pressurized coolant system with an expansion tank. It operates differently than most coolant systems that have an overflow reservoir.
- Always check the BMW coolant level when the car is cold, and the engine is turned off. The coolant system pressurizes, and if you remove the cap right after the engine has been running, it will still be hot.
- The hot coolant will cause injuries. To avoid getting burned, let the engine cool down for at least thirty minutes. If you are stuck on the side of the road and have no choice but to add coolant, remove the expansion cap very slowly.
- Keep your face and body as far aways you can.
- Allowing the BMW to idle and setting the heat on allows the air pockets in the cooling system to escape. If you suspected an air pocket in the engine and used this method, recheck the coolant level with the engine off. This will ensure you didn't overfill the system.
- If your BMW is under warranty, take your car to the dealer, and they will top off the cooling system free of charge.
Coolant level full, I still get low coolant warning light.
It is possible to get a Coolant Level too Low warning still even if you add coolant. The first thing that you need to inspect is the coolant level sensor if your BMW has one.
There may be an electrical issue with the sensor causing it to trigger the warning message.
If you are extremely low in coolant, you may get the low coolant warning light even if you add coolant. The car was either neglected or was extremely low in the coolant.
Run the car for one minute and recheck the coolant level. It is possible that you need to add more coolant.
Is the BMW coolant warning message on, even though the coolant level is correct?
This may be caused by outside temperature fluctuations or when using certain incompatible aftermarket coolant brands.
Other possibilities include a defective water pump, bad engine temperature sensor, or bad coolant level sensor.
Older BMWs had a translucent coolant reservoir with a line that shows the high and low levels. Back then, it wasn't necessary to remove the cap to get a coolant reading.
BMW redesigned the cooling system, and now they use an expansion tank. Instead of the transparent tank, they implement the float design ( the rod that pops up).
What BMW engine coolant should I use?
Use the OEM BMW Engine Coolant recommended in your owner's manual mixed 50/50.
BMW Coolant Alternatives
Not all aftermarket coolant is compatible with BMW cars. Here are a few coolant/antifreeze brands that are compatible with BMW:
Regardless of the coolant brand you use, including OEM BMW Coolant, always pre-mix it at 50% coolant and 50% water.
Full strength coolant is not mixed, and you will need to mix it yourself before adding it to the cooling system. Use distilled water instead of tap water.
Tap water will work, but it is not recommended because it can introduce impurities and minerals and cause corrosion to the cooling system.
You do not need any extra additives. The 50/50 mixture ratio can be used year-round.
Should I drive my BMW with the coolant warning light on?
NO. If the temperature gets above normal or you get a warning light that the engine is overheating, stop driving your BMW. Get it towed to a mechanic ASAP.
Frequently Asked Questions
When I check the coolant level, my BMW does not have a floating dipstick.
- The coolant level may be shallow, causing the float to be much lower than the min. In this case, it may be hard to see the float. Use a flashlight to look inside the coolant reservoir. If the float device is not present, it may be removed or broken.
Would BMW's low coolant level trigger the check engine light?
- No. Low coolant level warning should not turn on the service engine soon or check engine light. Unless the coolant system is almost empty, the engine temperature sensor may malfunction, triggering the check engine light.
What happens if you overfill the BMW cooling system?
- If you overfill the cooling system, it may cause it to be overpressurized. Excessive coolant will be released via the release valve on the cap.
What color is the BMW coolant?
- In most cases, the BMW coolant is a blue color.
Is it ok to mix or use a different brand coolant on BMW?
- Yes, but it's not recommended. With that said, it is better to have some coolant than driving a BMW with no coolant at all. Once you get your car to a mechanic, you may want to do a full system flush and install the correct BMW coolant.
Intermittent Cooling Warning Light
- If BMW coolant too low warning light comes on and then turns off, the level may have dropped slightly. Check the coolant level and add as necessary.
How can I tell if I have a coolant leak?
- When you have a BMW coolant leak, you will notice a distinct sweet smell that wasn't there before. You may smell coolant in the cabin. Or you may smell the coolant leak when the car is parked. After driving the BMW for a few minutes, open the hood and inspect for a coolant leak.