Audi A6
V6 naturally aspirated engine with 130 kW and smooth delivery. Timing chain on gearbox side, involved replacement. Adequately powered for the vehicle's weight.
Smooth Multi-Cylinder — Relaxed Cruising
177 hp 2.4L with a pleasantly smooth character. Cruises effortlessly without sporting ambitions. Factor in the known weak points.
Engine Weaknesses 6
The BDW is a chain engine. Chain tensioners can fail prematurely, causing the chain to stretch and timing to shift. Repair costs range from €1,000 to €3,500 depending on the extent of work.
Symptoms: Rattling at cold start from the engine bay, fault code P0346 (camshaft position sensor), rough idle
The BDW 2.4 V6 develops timing chain rattle at cold start from around 200,000 km due to chain stretch. An oil change can help temporarily but does not solve the problem permanently. Chain tensioner replacement is often possible without removing the engine.
Symptoms: Rattling at cold start that subsides after a short time. If ignored for long, noise becomes permanent.
The camshaft adjuster seals on the 2.4 V6 are known weak points. Oil leakage and resulting malfunctions of the adjustment mechanism require expensive repair (up to €1,750 at an Audi dealer).
Symptoms: Oil stains under the vehicle, oil smell, camshaft adjuster fault code, slight power loss or rough running
Individual ignition coils fail on the 2.4 V6 BDW, often triggered by faulty ignition cables or damaged connectors. Secondary damage to spark plugs or even the catalytic converter is possible.
Symptoms: Misfires, juddering under load, engine warning light, rough idle at certain rpm
The 2.4 V6 BDW can show elevated oil consumption (initially up to 1 l/2,000 km). Switching to 5W-40 oil often resolves the issue. The cause is usually valve stem seals or piston rings.
Symptoms: Oil level drops noticeably between oil changes, occasional blue smoke at cold start or under load
Like other naturally aspirated V6 engines, the BDW 2.4 V6 shows elevated oil consumption due to aging valve stem seals. Around 0.5–1 l/1,000 km at high mileages is common.
Symptoms: Oil top-ups needed, faint blue exhaust smoke at cold start
Vehicle Weaknesses 12
The continuously variable Multitronic gearbox (01J/0AW) is considered the most serious weakness. Judder, rev fluctuations and complete failure. Early build years up to 2007 are particularly badly affected.
Blocked drain channels under the battery and sunroof allow water to enter the cabin. The comfort control module in the driver's footwell is damaged, leading to MMI total failure.
The Multitronic CVT tends to judder when pulling away, rpm fluctuations at partial load and, in the worst case, complete failure. All front-wheel-drive models are affected.
The high vehicle weight (up to two tonnes) accelerates wear of control arms, joints and anti-roll bar bushes. From around 150,000 km, extensive suspension work is virtually unavoidable.
Older A6 C6 examples show corrosion starting at the sills, door sill lower edges and tailgate. Where paint is damaged in the underbody area, corrosion progresses rapidly.
The cast-aluminium front control arms are prone to rubber bush wear. The long steel bolts in the wheel carrier corrode particularly badly and become extremely difficult to remove.
Pre-facelift vehicles (up to 2001) in particular show rust at the front wheel arches, door sill lower edges, and on the Avant at the roof edge above the windscreen.
Blocked drain holes under the battery lead to water ingress into the interior and can damage control units. Leaking cabin air filter housing seals exacerbate the problem.
The shaft seal between gearbox and propshaft on the A6 C5 eventually loses its seal. Gearbox oil drips onto the catalytic converter and burns off there. Often only diagnosed by smell or visual inspection from underneath.
The xenon headlights are susceptible to age-related failure. Bulbs and ballasts fail with increasing age. Rear lights absorb moisture through leaking seals.
The panoramic or sliding sunroof tends to leak, especially when the drain hoses are blocked. Result: water ingress into the interior.
The soft-touch coating on door handles, light switches and surrounds of the A6 C5 peels away at frequently touched spots, leaving a greasy surface. Almost all vehicles over 10 years old show this.