BMW of North America recently announced two recalls covering about 1m vehicles that contain parts implicated in car fires investigated by a TV news organisation.

Though the recalls span six production years and numerous models, one of the recalls involves a crankcase ventilation valve heater that can cause fires in vehicles that are not in operation, reminiscent of some of the mystery fires that were the subject of an ABC News investigation that aired on various programmes in the US in May.

The investigation in collaboration with ABC-owned stations in a number of US cities, found over 40 cases in the last five years in which BMW owners said that parked cars that were not then subject to recalls for fire-related issues spontaneously burst into flames. Some of them, they said, had been turned off for hours or even days.

An article on the ABC News website shows three cars in flames - a 2008 X5 that also destroyed its owner's house and garage, a 2011 3 series sedan and a 2005 Z4. Video can be seen by following this link.

Using the NHTSA recall database, ABC News found that 12 of those vehicles identified in the ABC News investigation were subject to one or both of the new recalls. In a written statement sent to ABC News, a BMW US spokesman acknowledged the voluntary recall.

"At BMW the safety of our customers is a top priority," said spokesman Hector Arellano-Belloc in the statement. "We understand the serious nature of a vehicle fire, which is why we are taking appropriate steps to repair our customers' vehicles."

Last May, an NHTSA spokesperson told ABC News the agency was monitoring BMW vehicle fired and urged anyone with information to contact it.

ABC News said one recall involves the positive crankcase ventilation (PCV) valve heater while the other recall involves wiring and electrical connectors in the system that controls air flow for heating and air conditioning.

The PCV valve heater recall affects 740,561 BMW vehicles from these models and years: 128i from 2008 through 2011; and the 328i, 525i, 528i, 530i, X3. X5 and Z4 from 2007 through 2011.

The blower motor system connectors recall affects 672,775 vehicles of these models and years: 323i, 325i, 325xi, 328i, 328xi, 330i, 330xi, 335i, 335xi and M3 from 2006 through 2011; 335is from 2007 through 2011; and the 335d from 2009 through 2011.

Connectors coated with tin potentially can corrode leading to increased current loading, heat and smouldering or fire. Some BMW harnesses have silver coated connectors instead and are not potentially at risk.

Some of the 3-series models are listed in both recalls, bringing the total number of vehicles affected to about 1m, ABC News said. Dealers will fix the vehicles for free from an expected start date of 18 December.

Joseph Santoli, a New Jersey-based attorney who has sued BMW in the past, described the new recalls to ABC News as a "step in the right direction" but says the mystery of the parked BMW fires was far from solved. In some cases, the vehicles had been so badly burned it was difficult to determine a cause, and in other cases, the fires were determined to have started elsewhere on the vehicle, Santoli said.

"I really think that they have to do a comprehensive study of what is causing all of these fires and they have to work much more closely with NHTSA," Santoli said of the car company.

He added that in some cases, consumers have been asked to sign blanket confidentiality agreements.

"That just compounds and exacerbates the problem," he said.

ABC News said that, according to chronology reports provided by BMW to NHTSA, BMW had looked into heat damage involving the heating and cooling system as early as 2007 but stepped up its analysis work in September. The issue with the valve heater first came to the carmaker's attention in 2009 and tests were performed in 2011 and 2012. The carmaker met with NHTSA in October and issued the recalls.

BMW told ABC News last spring that with almost 5m BMW vehicles on US roads, such fire incidents were rare, and suggested other causes might be to blame, such as a lack of maintenance, improper maintenance by unauthorised mechanics, aftermarket modifications, rodent nesting and even arson. The carmaker said that based on its investigation, they had "not seen any pattern related to quality or component failure. Vehicle fires can result from a wide variety of external reasons unrelated to product defect."

BMW has said that, so far, the voluntary recalls affect only 1m cars sold in the US and 15,000 in Canada and it is investigating if the campaign needs to be expanded to other markets.

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