Following a system failure that forced Toyota to suspend production at all of its 14 Japan assembly plants, the company announced operations would resume Wednesday, Aug. 30. Twelve of the plants will get back to work Wednesday morning, with the other two resuming production in the afternoon.

In a statement, Toyota described the system failure affecting its Japan plants as “a malfunction in the production order system” that happened Monday, Aug. 28.

“It is our understanding that the malfunction of the system was not caused by a cyberattack. However, we will continue to investigate the cause,” the company said. “We would like to apologize once again to our customers, suppliers, and related parties for any inconvenience caused by the suspension of operations.”

According to analysts, Toyota could be tested in making up for output lost during the outage.

“Output was running at full capacity so there’s little additional room for production,” Seiji Sugiura, an analyst at Tokai Tokyo Research Institute, told Reuters.

Toyota’s Japanese plants account for about a third of the automaker’s global production, according to Reuters calculations. Plants in Japan produced an average of 13,500 cars per day in the first half of 2023.

Domestic production had been on the rebound for Toyota after a series of output cuts the company blamed on semiconductor shortages. Output was up 29% in the first half of the year, the first such increase in two years.

While the cause of system failure was unclear, corporate Japan has been on alert in recent days as businesses and government offices reported harassing phone calls. The government said the calls were likely from China, related to Japan’s release of treated radioactive water from the Fukushima Nuclear Power Plant into the Pacific Ocean.