Isuzu 4JJ

Isuzu's 3.0-litre common-rail diesel — the engine of the D-Max and MU-X, and, because Isuzu supplies engines widely, of a number of light commercial vehicles under other badges.

It has a strong reputation for durability in heavy use, which is the point of it: these are working vehicles, and the engine is built for load rather than refinement. The failures that occur are overwhelmingly duty-cycle and maintenance failures — injector wear where fuel quality is poor, turbocharger variable-geometry mechanisms sticking with carbon, and EGR blockage on vehicles doing low-speed work.

On the later emissions-equipped versions the diesel particulate filter joins the list, with the same short-journey problem as everywhere else and the same oil-dilution consequence. Given the work these vehicles do, the useful diagnostic question is usually what the vehicle is used for rather than how far it has travelled.