Hyundai and Kia's Theta II engine: metal debris, then a $1.3B settlement

Hyundai's Theta II GDI engine, built at the company's Alabama plant and shared with Kia's Optima, Sorento and Sportage, was assembled with metallic manufacturing debris left inside the block near the crankshaft. The debris blocked oil flow to the connecting-rod bearings, starving them of lubrication.

Under-lubricated bearings wore down and could cause the connecting rod to seize or, in some cases, punch through the engine block, leaking oil that could ignite and start a fire. A knocking noise was the main warning sign available to drivers before failure.

Hyundai issued an initial, limited recall in 2015 and expanded it in 2017 as Kia joined the recall effort for its shared-engine models; further expansions followed through 2018 as regulators and litigation pushed the scope wider. In May 2021 a federal court granted final approval of a $1.3 billion class-action settlement covering roughly 1.05 million Hyundai and 1.16 million Kia vehicles from model years 2011 to 2018, providing a lifetime engine warranty, a knock-sensor detection software update, and reimbursement for repairs and lost value.