Here are the steps on how to check the coolant level in a BMW:
The coolant level should be between the "MIN" and "MAX" marks on the reservoir. If the level is below the "MIN" mark, you will need to add more coolant.
To add coolant, use a funnel to pour the coolant into the reservoir. Be sure to use the correct type of coolant for your BMW.
Look inside the reservoir for a float. The float is a small, plastic device that will move up and down depending on the level of coolant in the reservoir.
There will be a cap on the reservoir. Slowly turn the cap counterclockwise to release any pressure that may be built up in the system.
Check the coolant level without the cap. The reservoir side “MIN” and “MAX” markers should have coolant.
Open the hood and locate the coolant reservoir. It is typically a small, black tank located on the left side of the engine bay.