An investigation by Ford found that the F-150 Regular and SuperCrew cab vehicles in north America have been fitted with the faulty pretensioners, which can generate excessive sparks and gas that if ignited, could cause insulation or carpet to catch fire.
"Ford’s investigation found that some front seat belt pretensioners can generate excessive sparks when they deploy," the company said in a statement on its website. "When sufficient sparks are present, gases exhausted inside the lower portion of the B-pillar by the pretensioners may ignite. If this gas ignites, components behind the B-pillar such as insulation and carpet may subsequently catch fire."
So far there have been 17 reports of smoke or fire in the US and six in Canada, but no reported accidents or injuries.
Affected vehicles include F-150 vehicles built at Dearborn assembly plant from March 2014 to August 2018 and F-150 vehicles built at Kansas City assembly plant from August 2014 to August 2018.
There are approximately 1,995,776 affected cars in north America; 1,619,112 cars in the US and its federalised territories, 339,884 in Canada and 36,780 in Mexico.
All repairs will be carried out at no cost to the customer, Ford said.
In May this year BMW recalled 312,000 vehicles after the BBC's Watchdog found that they could cut out completely while being driven.