Citroën C6

The turbocharger on the 2.2 HDi UHZ wears sooner than in private-car use due to high mileage and commercial vehicle loading. Oil sludge from extended service intervals is a frequent cause. Flushing the turbo oil feed line at every oil change is recommended.

Symptoms: Whistling, power loss, blue exhaust smoke, oil in intake hose.

Copper seals and rubber seals on the 2.2 HDi injectors leak under high temperature swings and intensive load operation. Leaking injectors contaminate the oil and cause combustion gas blow-by.

Symptoms: Soot deposits around injectors, oil contamination in engine bay, rough idle.

Commercial operation with short trips is harmful to the DPF. The EOLYS-based FAP system only regenerates on sufficiently long journeys. In urban delivery use, regenerations frequently fail and the filter clogs prematurely.

Symptoms: FAP warning light, limp mode, strong fuel smell, increased fuel consumption.

The timing chain of the 3.0 HDi V6 (UHZ) stretches at higher mileages. In rare cases the camshaft sprocket spins on its taper, causing immediate engine failure. Timing tools are required for adjustment work.

Symptoms: Rattling from the timing area on cold start, rough idle, engine warning light with camshaft fault, in the worst case abrupt engine failure.

The 3.0 HDi V6 has two turbochargers that suffer bearing damage from oil sludge caused by infrequent oil changes or short-trip driving. When one turbo fails, power loss and high oil consumption result.

Symptoms: Whistling turbo noise, heavy blue smoke from exhaust, noticeable power loss especially in the upper rev range, increased oil consumption.

The vacuum actuator for the swirl flaps on the 3.0 HDi V6 has a rubber diaphragm that is cut and worn through by sharp plastic edges. The actuator then loses vacuum and the flaps are no longer controlled correctly.

Symptoms: Power loss at part load, reduced throttle response, swirl flap fault code, occasional limp mode under heavy load.

The Hydractive 3+ suspension on the C6 I fails from around 60,000–80,000 km with leaking spheres and cylinders. The car sinks on one or more corners and the ride becomes hard. Repair is labour-intensive and expensive; Citroën has discontinued spare parts.

The BSI and BSM central control units on the C6 I are no longer available from Citroën as spare parts. A fault in these ECUs can permanently immobilise the vehicle. Electronic problems with fault cascades (ABS, ESP, parking brake) appear from 50,000 km.

The automatic gearbox in the C6 I wears out its solenoid valves in the hydraulic block from 80,000–100,000 km. Jerky shifts and gearbox failures follow. A gearbox oil change with special ATF every 60,000 km is mandatory but is frequently ignored by previous owners.

The C6 I shows problems with brake lines at higher mileages (80,000–100,000 km) that can lead to pressure loss. Brake discs and pads wear above average, especially the front discs from 40,000–60,000 km.

The C6 I shows corrosion at wheel arch inner edges and on the underfloor, especially on vehicles without regular underbody sealing. Older examples from 2005–2007 are more severely affected.