The Tesla Model S vehicle fire that occurred in Shanghai this past April, prompting international media attention, was caused by a single battery module and is not a system defect, the company said Friday.

Tesla provided the update on the cause of the fire in a post Friday on its Weibo social media account. A team of investigators analyzed the battery, vehicle history, software and manufacturing data. The fire was caused by a single battery module at the front of the vehicle, Tesla said.

The company has issued a software update that will change battery charge and thermal management settings in Model S sedans and Model X SUVs.

This software update was first announced in May following the company’s investigation into another Model S fire in Hong Kong. In that incident, a Tesla Model S caught fire March 14 while parked near a Hong Kong shopping mall. The vehicle was sitting for about a half an hour before it burst into flames. Three explosions were seen on CCTV footage.

Tesla said, at the time, that the software update was being done out of “an abundance of caution.” The update is supposed to “protect the battery and improve its longevity.” The over-the-air software update will not be made to Model 3 vehicles.

The company added that while the probability of a Tesla electric vehicle fire is lower than a gasoline-powered vehicle, it takes any incident seriously.

Two other companies, Chinese automotive startup Nio and Audi, have issued recalls to due to risk of battery fire. In Audi’s case, there hasn’t been any reported fires. But the company went ahead and issued a voluntary recall in the U.S. for the E-Tron SUV after it found that moisture can seep into the battery cell through a wiring harness. There have been five cases worldwide where this has caused a battery fault warning.

Nio is grappling with a design issue in an older battery pack module. The company, which began deliveries of its ES8 SUV in June 2018, is recalling nearly 5,000 of the vehicles after a series of battery fires in China and a subsequent investigation revealed a vulnerability that created a safety risk.

A Nio-led team of experts that included the supplier of the battery pack module, investigated a reported fire involving an ES8 in Shanghai. The team concluded there was a vulnerability in the design of the battery pack that could cause a short circuit. In this case, battery packs in the vehicles involved were equipped with a module specification NEV-P50.

Vehicles with 70kWh battery packs produced after October 20, 2018 are equipped with the NEV-P102 modules and have different internal structural designs. These packs don’t have the same risk, Nio said.

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