Audi A6 C7 2.0 TFSI

The EA888 Gen 2 engine (CDNB/CDNC codes, 2011-2014) has a well-documented piston ring design problem that allows oil to enter the combustion chamber. Affected engines consume 0.5-1.0 litre per 1,000 km or more. Audi acknowledged the issue and revised piston ring tolerances from mid-2013 onwards. A US class-action settlement covered 2012-2014 models, offering partial repair coverage. The fix requires removing the engine to replace piston rings and occasionally the short block. Post-2014 Gen 3 engines with combined direct/port injection have largely resolved this issue. If buying a pre-facelift car, check oil level before and after a test drive and ask about top-up frequency.

The EA888 Gen 2 timing chain tensioner has gone through at least seven revisions, indicating a persistent design weakness. The tensioner's ratchet mechanism wears over time, allowing the piston to retract when the engine is off and oil pressure drops. On the next cold start, the chain runs slack for several seconds, causing a distinctive rattle. If the chain jumps a tooth, the result is valve-to-piston contact and catastrophic engine damage. This primarily affects 2011-2013 production cars. The Gen 3 engine moved the timing chain to the flywheel side and uses a more robust tensioner design. Replacement involves the chain, guides, tensioner, and sprockets. Listen carefully for any rattle during cold start lasting more than 2-3 seconds.

Pre-2014 front-wheel-drive A6 2.0 TFSI models came with the multitronic CVT (0AW). This transmission requires fluid changes every 60,000 km, though Audi initially marketed it as lifetime-filled. Neglected units develop input shaft bearing wear, chain slippage, and solenoid failures. Symptoms include juddering at low speeds, hesitation, and a rubber-band throttle feel. A mechatronic unit replacement costs around 1,500-2,000 euros; a complete transmission rebuild or replacement can reach 3,500-4,500 euros. The CVT was discontinued in 2014, replaced by the more robust S-tronic DL501 dual-clutch. If buying a pre-2014 car with CVT, verify that transmission fluid has been changed at least once and test extensively at low speeds on inclines.

The EA888 engine uses an integrated electric water pump and plastic thermostat housing that degrade over time. The thermostat housing is prone to developing hairline cracks that cause slow coolant leaks, sometimes recurring even after replacement. The water pump typically fails between 80,000 and 120,000 km. Symptoms include coolant warning light, overheating, or poor cabin heating. It is recommended to replace both components together when either fails. The Gen 3 engine has slightly improved housings but is not immune to this issue.

Like all direct-injection petrol engines, the 2.0 TFSI accumulates carbon deposits on the intake valves because fuel is sprayed directly into the combustion chamber rather than across the valves. This is exacerbated by oil vapour from the PCV system coating the valves. Symptoms include rough idle, hesitation, reduced power, and increased fuel consumption, typically becoming noticeable after 60,000-80,000 km. Walnut blasting (media blasting the intake valves) is the standard fix and costs 400-800 euros depending on the shop. The Gen 3 engine's combined injection system (direct + port) partially mitigates this by using port injection at low loads to keep valves cleaner, but carbon buildup still occurs over time.

The A6 C7 uses a multi-link front suspension with aluminium control arms. The rubber bushings in these arms deteriorate over time, causing clunking over bumps, vague steering, and uneven tyre wear. This typically becomes noticeable around 80,000-120,000 km. Audi uses integrated control arm assemblies where the bushing cannot be replaced separately, so the entire arm must be swapped. The front suspension has four control arms per side. Replacing all eight arms with alignment costs 800-1,200 euros at an independent specialist using aftermarket parts, or 1,500-1,800 euros at an Audi dealer with OEM components.

Post-2014 A6 models equipped with the 7-speed S-tronic (DL501/0B5) dual-clutch gearbox can experience mechatronic unit failures. Internal electronics degrade from heat exposure, causing harsh shifting, loss of gears, limp mode, or no reverse. Audi has released an upgraded unit with a larger heat sink. Mechatronic repair with a specialist kit costs around 1,500 euros; full unit replacement at a dealer runs 2,500-3,000 euros. Regular fluid changes every 60,000 km and avoiding prolonged stop-and-go traffic help extend its lifespan. The DL501 is generally considered more robust than the multitronic CVT it replaced.