Toyota is recalling 2 million vehicles in the U.S., saying an error during the manufacturing of a power window switch may cause a vehicle fire.

A dozen different Toyota models are involved in the recall, including the 2007 and 2009 Camry Hybrid, and 2008-2011 Highlander Hybrid SUVs.

The problem lies in the power window master switch, mounted on the driver’s side of the car. When the switch is built, its sliding electrical contacts are lubricated with a spray-on grease.

However, this grease “may have been applied inconsistently during the manufacturing process, not providing sufficient coverage,” Toyota said. “During normal operation, debris caused by wear from the electrical contact points can accumulate between the terminals where the grease was insufficiently applied, and a short circuit could form between the contact points by the debris and conductive moisture that may enter the module.

“If a short circuit occurs, the switch assembly may overheat and melt. A melting switch may produce smoking and, potentially, lead to a fire.”

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This isn’t the first time Toyota has problems with greasing its window switches.

“Earlier recalls for the part, which is made by a Japan-based supplier, Tokai Rika, were ordered because too much heat-resistant grease was used to coat the switches’ internal mechanisms,” reported The New York Times.

The current recall adds 6.5 million vehicles to Toyota’s worldwide list, bringing the global total of vehicles potentially affected by faulty window switches to 14 million. According to Toyota, about 2 million of these are located in the U.S.