A manufacturing issue was identified in a small batch of 2021-2023 Mini Hardtop 2 Door Cooper SE vehicles. These electric cars were found to have a high voltage battery housing that did not meet the company’s assembly specifications. This discovery came to light after a concerning incident in the U.S. in October 2023, where one such vehicle experienced what is known as a thermal event—a significant overheating.

Following this incident, BMW initiated a thorough engineering analysis to pinpoint the cause. It was found that during certain production periods, there was a flaw in how the battery housing was sealed. Specifically, an inadequate amount of sealing compound was applied between the two halves of the battery module’s housing. This oversight made it possible for water to seep into the battery enclosure.

Water entering the high voltage battery compartment can trigger what is called an isolation fault. This type of fault compromises the battery’s integrity, leading to performance issues and safety concerns. Initially, such water ingress prompts the vehicle to display a warning message, alerting the driver of the fault and advising them to have the vehicle checked at a MINI service center.

Should the water exposure continue, the situation can escalate. The accumulation of moisture can cause multiple isolation faults, potentially causing the vehicle to stall. In more severe cases, particularly after long periods of inactivity, these faults could cause the battery to overheat significantly. Such overheating, while rare, could lead to a thermal event, even if the car is not in use.

To address this issue, BMW is recalling affected vehicles to inspect, and if necessary, repair the sealing of the battery housing. This includes a thorough leak test to ensure the integrity of the battery enclosure. Owners of the affected Mini Cooper SE models will be notified by mail with instructions to visit their dealer. Notification letters are scheduled to be sent out on June 21, 2024. The recall has been officially recorded under the NHTSA campaign number 24V-302.

Vehicle owners are encouraged to respond to the recall notice promptly to ensure their safety and the proper functioning of their vehicle.