Community-reported known issues, by make and model.
The Focus ST 250's 2.0 EcoBoost and the smaller 1.6 EcoBoost in other Mk3 Focus models can develop a worn timing chain tensioner, causing a rattle on cold start that clears once oil pressure builds.
The EA888 2.0 TFSI engine (shared across A3, Golf GTI, Leon Cupra of this generation) can suffer timing chain stretch and premature high-pressure fuel pump cam follower wear.
The EA111 1.2 TSI engine used in the Polo (and shared across the VAG group) has a known weak timing chain tensioner that can fail suddenly, which in the worst case allows the chain to jump and cause serious engine damage.
The dry-clutch DQ200 7-speed DSG gearbox fitted to many smaller-engined Golfs of this era is known for mechatronic unit failures, causing jerky shifting or the gearbox to enter limp mode.
Early S55 twin-turbo engines in the F80 M3 and F82 M4 had a batch of cars with premature rod bearing wear, prompting a BMW service campaign to check bearing condition.
The twin-turbo N54 straight-six is a well-loved tuning engine, but the factory high-pressure fuel pump has a known failure mode that leaves the car struggling to start or running rough.
The N47 four-cylinder diesel (used across the E90 3 Series and other models of this era) is well known for premature timing chain stretch. Unlike most engines, the chain is at the transmission end, making it a much bigger job to replace.
Same 1.0 EcoBoost engine as used in the Fiesta of this era: a cracked cylinder head or head gasket failure linked to the coolant system, particularly the plastic coolant elbow near the thermostat housing.
The 1.0 EcoBoost three-cylinder engine is prone to a cracked cylinder head or blown head gasket, usually caused by the coolant system (a thin plastic coolant elbow) failing and allowing the engine to run low on coolant without an obvious warning.