The system failure which prompted a shutdown of Toyota’s domestic plants earlier this week was caused by a parts ordering system update, sources have told Reuters.

There were 14 plants affected, along with 28 vehicle assembly lines.

The automaker stopped production for a full day as investigations were made.

A cyberattack was considered ‘unlikely’, a Toyota spokesperson said previously.

Reuters estimates that the cost of the stoppage could be around $356 million of revenue.

Toyota has not given details of what went wrong, clarifying only that it was not a cyberattack.