Back in May, Ford recalled 39,013 Expeditions and Lincoln Navigators from the 2021 model year that were built between December 1st, 2020 and April 30th, 2021.

At the time, the company said they had received 16 reports about a fire including 12 that occurred while the vehicle was parked with the ignition turned off. Ford began investigating the issue on March 24th, but hadn’t determined a cause so they issued a recall and told owners to park outside and away from buildings.

The company has now found a fix as well as announced plans to expand the recall to include 66,221 vehicles built between July 27th, 2020 and August 31st, 2021. The automaker believes the cause of the fires can be “traced to a change in manufacturing location by a supplier during the COVID-19 pandemic.” As they explained, “printed circuit boards produced at this facility are uniquely susceptible to a high-current short and were supplied to Ford and installed in Expedition and Navigator SUVs produced during the recall window.”

Also Read: Ford Expedition And Lincoln Navigator Owners Being Asked To Park Outside Over Fire Risk, 16 Incidents Already Reported

As part of the remedy, dealers will first inspect the battery junction box for signs of “melting damage.” If there are any indications of this, the entire component will be replaced.

After that inspection, technicians will “remove the engine fan ground wire from the battery junction box in affected vehicles with an 800-watt cooling fan system, which represents about one-third of the recalled vehicle population. For the remaining affected vehicles with a 700-watt cooling fan system, the repair is the same, except for the installation of an auxiliary box with a wire jumper.”

Ford noted repairs for models with the 800-watt cooling fan system can begin immediately, while parts for SUVs with the 700-watt cooling fan system are expected to be available in early September. That’s a bit of a wait, but owners will be notified when parts become available.

Ford has received a total of 21 reports about under hood fires, including five since the original recall in May. This is a serious problem and the company is advising owners to continue parking outside and away from structures until their vehicle is fixed.