YOKOHAMA-SHI, KANAGAWA, JAPAN - Nissan Motor Co. said it is now investigating reports that a small number of Leaf electric vehicle owners have experienced problems restarting the car after it has been shut down, Fortune reported. 

Nissan said this past weekend that the problem may be linked to a sensor in the air conditioning system. The automaker added it is actively working to identify the root cause of the problem and to develop a remedy. However, no safety recall is planned since the problem poses no safety risk.

Only 452 Leafs have been delivered to the U.S. The Leaf is built in Japan, and Nissan is struggling to keep pace with demand -- especially since the earthquake, tsunami and nuclear crises.