DNFC engine faults.

In these engines the oil pump is adjustable, and the factory setting deliberately keeps the oil pressure low at low revs to reduce the drag of driving it. At low revs the stock pump works at around 1.8 bar, up to 2 bar at most. With a warm engine at idle this can fall further, and values below 1 bar have been reported. The camshaft adjusters feel the low pressure first, because the oil pressure itself is what holds the adjuster in place: this is where the clacking noise heard at idle comes from. The chain tensioner follows, which the same pressure tensions, and the timing chain therefore wears faster. The reference values for this engine family are 2 bar at idle, 3 bar at 2,000 rpm and 4.5 bar at 4,000 rpm. The turbocharger and the camshaft are lubricated from the same circuit. A strengthened oil pump raises the idle pressure by about 20 per cent. Repairing the pump costs between 800 and 2,800 euro, and replacing a worn chain is a further 1,200 to 3,500 euro.

The combined housing of the water pump and the thermostat is plastic, and it is bolted directly to the hot engine block. The many heat and cool cycles warp it, it becomes brittle, and then it develops a hairline crack: the fault is almost always the housing, not the pump itself. The signs are slowly disappearing coolant with no visible puddle, the coolant level light, a sweet smell from the engine bay, and later a pink stain under the car. The repair means replacing the pump and the housing together, and the intake manifold has to come off for it: 4 to 6 hours of work. It shows up on model years 2015 to 2025.