Tesla has determined the cause of a dramatic fire that engulfed one of its cars in a Shanghai parking lot in April, and says the battery was to blame.

Reuters reports that the automaker posted the news to its Weibo social media account, explaining that it tracked the issue back to a faulty module in the battery pack of the Model S. Details on the fault were not shared, but Tesla said it found no system defect.

Security camera footage of the incident shows smoke coming from under the car before it bursts into flames. Teslas are powered by thousands of cells that are grouped into a number of modules, which varies with the size of the pack. There are sixteen of them in its 85 kilowatt-hour capacity battery, for example, according to Electrek.

The Model S and X, pictured above, use a floor-mounted battery pack. (Getty Images)

Tesla said in the post that it has sent an over the air software update for the Model S and X to revised the charge and thermal management settings “to help further protect the battery and improve battery longevity,” which it previously announced in May.