General Motors Co. is expanding its safety recall of the all-electric Chevy Bolt to include newer models, an action that will cost an additional $1 billion to remedy a problem that has increased the risk of battery fires in this particular vehicle.

The expansion adds another 73,000 Bolt electric vehicles to GM’s recall campaign and includes 2019 models not covered under the previous action, as well as 2020-2021 model-year vehicles, the company said Friday.

GM’s stock, which closed at $48.80 Friday, was down 2% in after hours trading.

The Detroit auto maker last year recalled about 69,000 older model-year Bolts, saying it was aware of five fires involving the cars and advising owners not park the vehicles in garages until they can get them fixed. In July, it recalled the same Bolts for a second time because of a potential battery defect that could result in a fire.

At the time, GM said it had since learned of one battery fire that occurred after the vehicle had received a software update intended to fix the problem.

While the Chevy Bolt is considered a relatively low-volume model, the expense of fixing defects related to the battery-fire risks are mounting for the car company, which has bet big on shifting more of its lineup to electric vehicles. GM has said that the earlier recalls involving the Bolt have cost it about $800 million so far.

Auto makers are accelerating their shift away from gas-powered vehicles by adding more plug-in models to their lineup, a transition that has been driven in large part by tougher auto emissions regulations globally.

The technology, however, is still maturing and several new-model launches have already been marred by concerns about the lithium-ion batteries catching fire, a risk that has long been present in other consumer electronics.

A 2019 Chevrolet Bolt EV after it caught fire July 1 in Thetford, Vt., The image was later released by the Vermont State Police.

Photo: -/Agence France-Presse/Getty Images

In the newer Bolts, GM said it discovered two manufacturing defects in the battery cell that could increase the risk of fire. The company said it is working with battery supplier LG Chem Ltd. to increase production of the replacement parts and will notify owners when they are available. GM said it plans to replace the entire battery module with a new one in the affected vehicles.

For now, the car company is asking Bolt owners to park their vehicles outside and limit charging the battery to 90% to reduce the fire risk. It is also recommending owners avoid depleting the battery to below 70 miles of driving range.

Write to Nora Naughton at Nora.Naughton@wsj.com