The oil pump is driven by a separate, smaller chain from the crankshaft, behind the timing chain at the front of the engine. This chain runs on plastic guides, and under heat cycles the plastic cracks, flakes off and finally disintegrates. From then on the chain works against the aluminium, the tension is lost, and the stretch progresses fast.

It causes damage along two paths, and the less known one comes first. The broken pieces of plastic are sucked into the oil pickup tube, block the way of the oil there, and destroy the bearings before the chain has even jumped. The other path is the chain or the tensioner letting go: then the oil pressure disappears within seconds, and the engine can seize without stopping.

The warning is not the lamp. This fault does not always light a warning, so the noise is what to listen for: between 1500 and 2500 revs a high, whistling whine comes from the lower part of the engine, and at a cold start a rattle of one to five seconds is audible. The maker issued its own service bulletin for the whining noise on the N20 and the N26.

On the factory chain the fault is reported above 80 000 miles, that is above roughly 129 000 kilometres, but in the American settlement the maker took it on earlier as well: below 70 000 miles, that is 113 000 kilometres, the full cost, and above 100 000 miles or eight years nothing at all. The affected set is the N20 and N26 engines built between 2012 and 2015.

The repair costs between 4000 and 6000 dollars, because the work on the timing and on the oil pump go together. If someone has replaced the timing chain, the oil pump chain has to be replaced with it: if the job is left half done, the engine has to come apart again in a few years.