Audi A4

The timing chain of the 2.7 TDI V6 can stretch prematurely, especially with short-trip use and infrequent oil changes. Rattling at cold start is the warning sign. Full chain kit replacement costs €1,500–3,500.

Symptoms: Rattling or clattering right after cold start, engine management faults in memory, engine stalling in worst case

The EGR system on the 2.7 TDI V6 sits in the poorly accessible V-space between cylinder banks. Valve and cooler carbon up; the cooler can develop leaks and lose coolant.

Symptoms: Juddering and power loss, coolant loss without visible external leak, engine warning light with EGR fault code

The piezo injectors in the 2.7 TDI reach the end of their service life at very high mileages. Individual replacement is possible, but all 6 are often changed at the same time.

Symptoms: Rough running, elevated fuel consumption, smoke clouds at cold start, fault code for individual cylinders

Shutting off immediately after hard driving and insufficient oil warm-up at cold start accelerate turbocharger bearing wear. A failure leads to oil leaks and potentially total engine damage.

Symptoms: Whistling or grinding noise from the turbo area, bluish smoke, power loss, oil loss

The oil-to-water heat exchanger can develop leaks at high mileages, mixing coolant into the engine oil or passing oil into the cooling system. A relatively inexpensive replacement prevents engine damage.

Symptoms: Milky residue on the oil filler cap, coolant level drops without visible loss, oil looks milky-brown

The CVT Multitronic (type 0AW) is known for frequent failures through 2011. Juddering, imprecise shifting or complete failure from around 150,000 km. Expensive reconditioning or replacement required.

Water ingress through the rear lights can short-circuit the wiring harness and cause expensive electrical damage. A weak starter battery is a recurring issue since many systems draw power continuously.

The complex front axle shows wear at higher mileages in suspension components, control arm bushings and springs. Brake hoses regularly appear on repair lists.

On TFSI petrol engines the coolant water pump is a known wear point between 50,000 and 100,000 km. Loose hose clamps can also lead to coolant loss.

The S tronic dual-clutch gearbox is sensitive to frequent city driving and towing. Clutch judder and shifting problems occur. Regular gearbox oil changes extend service life.

Springs break through corrosion on the powder coating after stone chip damage. Front axle springs particularly affected. A broken spring can damage the tyre.

Rear brake calipers seize, particularly after winter periods. Defective seals allow water ingress and pistons corrode.