Exhaust Gas Recirculation (EGR) systems trap exhaust gases and, as the name implies, recirculate them back into the engine. This helps cut down on Nitrogen Oxide (NOx) being released into the environment. The EGR cooler makes sure those hot exhuast gasses won't melt the engine's air intake by exchanging heat with engine coolant.
Since late October, Fiat-Chrysler (FCA) has received 119 customer assistance records, 6 field reports, and 1,478 warranty claims filed about EGR cooler problems. An internal investigation showed that the coolers can crack due to "thermal fatique" which is usually how they fail considering they don't have any moving parts.
The cracks allow engine coolant to leak out and since coolant is flammable + exhaust gases are super heated, all it takes is one small spark to start a large engine fire.
FCA says the recalled SUVs began production in December 2012 and ended in January 2019. It would have been nice to see the automaker be more proactive with this problem considering they recalled 160,000 Ram 1500 trucks for the same EGR cooler leaks last fall.