As we reported about a month ago, the NHTSA was sniffing around the Chevrolet Bolt due to a small number of fires that occurred in the EVs while they were parked.

Now after launching its own internal investigation, GM is issuing a recall of the vast majority of Bolts produced.

The investigation was launched after there were two reported fires in Bolts, one a 2018 model year, the other a 2019. Things got more serious when the NHTSA reviewed some more records and found it had already heard of a fire in a 2017 Bolt as well. The fires occurred in Bolts while they were parked, had nearly full or full battery charge, and the flames spread from underneath the rear passenger seat.

Once alerted by the NHTSA, General Motors started its own investigation and identified fires in five total Bolt fires - two more than cited by the NHTSA. GM has traced the source of the fire to the Bolt's high-voltage batteries, which were produced in South Korea by LG Chem.

The recall includes Bolts from model years 2017 through 2019. 77,842 Bolts were made between 2017 and 2020, and the recall affects 68,667 units. The vast majority were sold within the US, as the Bolt proved unpopular in other markets. 50,295 owners across the nation were issued recall notices on Friday.

GM says they don't know what's causing the fires and are working to make that determination. They plan to have a fix after the first of the year. That means the dollar hit from a recall gets reported with 2021 financials instead of the already tarnished 2020 ones.

The General does not think all recalled cars are affected by the battery issue, but is casting a wider net for an abundance of caution. Bolts from 2017 and 2018 used the same Korean-sourced LG Chem batteries, but the usage was mixed for 2019: Some had LG batteries from Korea, while others had similar LG batteries made in Michigan. For 2020, the Bolt implemented different battery chemistry which improved range.

Until a fix is found, GM is informing customers with 2017 and 2018 Bolts to run their hatchbacks in Hilltop Reserve mode. In 2019 Bolts, the present instruction is for owners to set their Bolts to charge to a max of 90 percent. Accompanying videos have been created to show customers how to make these changes themselves and avoid a trip to the dealer.

a version of this article first appeared on TTAC