A manufacturing mix-up led to the installation of head gaskets intended for the Ford Mustang EcoBoost, which has a different cooling passage design.

Buying a used Ford Focus RS (Mk3, 2016–2018) is a thrilling prospect for any driving enthusiast, but it requires careful homework. While it is a "four-door super hatch" with 350 hp and advanced all-wheel drive, certain mechanical pitfalls and ownership histories can turn a dream car into a financial nightmare.

Beyond the head gasket, keep an eye on these common "Focus quirks":

The most infamous issue with the Focus RS concerns the head gasket in .

This flaw causes coolant to burn, leading to white smoke from the exhaust, misfires, and potentially catastrophic engine failure (hydrolock).