The PSA XU is a family of internal combustion engines used in Citroën and Peugeot automobiles.

Displacement ranged between 1.6 and 2.0 L (1,580 and 1,998 cc), and all production XU gasoline engines had a bore of 83 or 86 mm (3.27 or 3.39 in).

Many versions were produced, from a double-barrel carburetted 8-valve to a 16-valve DOHC fuel injected model.

The XU10 has a cast iron block with a displacement of 2.0 L (1,998 cc), with a bore and stroke of 86 mm (3.39 in), making it a square engine.

Many versions were produced, from a double-barrel carburetted 8-valve to a 16-valve DOHC, fuel injected, turbocharged model.