Tesla has issued a software update for more than 1.8 million vehicles in the US to fix a faulty notification system for unlatched bonnets, also known as hoods in the US.

In a recall notice, US safety regulators said a flawed part meant the cars might not be able to detect and alert drivers when the front cover piece is unlatched, risking it flying fully open when the car starts moving.

Tesla started investigating the problem in March, after complaints of "unintended hood opening events" emerged in China, where the part was made.

The recall affects a significant number of vehicles made by the company in recent years, including certain Model 3, Model S and Model X cars made since 2020.

Tesla's investigation found the issues were more prevalent in China than in Europe or North America, "for reasons unknown", according to National Highway Traffic Safety Administration (NHTSA) documents published about the recall.

In the US, the company said it knew of just three reports potentially related to the problem and was not aware of any accidents or injuries.

This month, "out of an abundance of caution while all engineering studies continue, Tesla made a determination to voluntarily recall affected vehicles," according to the NHTSA documents.

Tesla had started sending the software updates to customers in June. Just 1% of the vehicles involved in the recall are actually likely to have the defect, according to the notice.

It is the latest recall notice to involve Elon Musk's electric car company, which has ramped up production dramatically over the last few years.

The biggest involved safety updates for its auto-pilot system for more than two million cars late last year.

In 2021, the company also faced a recall related to faulty bonnet latches, some of which were misaligned and put the piece at increased risk of popping open.

In that case, the recall targeted about 119,000 Model S luxury sedans and required reassembly of the secondary latch.