Prince (EP6 / N13)

A 1.4–1.6 litre all-aluminium four developed jointly by BMW and PSA Peugeot Citroën, and the clearest case in the catalogue of one engine with two identities: PSA sells it as the EP6 in its THP and VTi forms, BMW as the N14, N18 and N13 in the MINI and 1 Series. A MINI Cooper S and a Peugeot 207 GTi share an engine, and a fault documented under one designation applies directly to the other. This entry carries no single designer for that reason.

The timing chain is the defining failure. Chain and tensioner wear produce a cold-start rattle and, left alone, jumped timing; the same engine's variable valve lift hardware on the naturally aspirated variants adds a second mechanism with overlapping symptoms, so a rough-running VTi is worth distinguishing from a rough-running THP before parts are ordered.

Carbon on the intake valves is heavy on the direct-injected turbo variants, and high-pressure fuel pump wear is common. Oil consumption is expected rather than exceptional — check level before diagnosing anything else, since low oil accelerates the chain problem that ends the engine.