A comfortable executive diesel cruiser popular with business users. The 2.0 TDI is the most fuel-efficient A6 option (4.3-4.9 L/100km). Early cars use the EA189 engine (involved in dieselgate), post-2014 facelift models use the improved EA288. Main concerns: high-pressure fuel pump (CP4) failures can contaminate the entire fuel system, DPF clogging on city-driven cars, timing belt requires replacement at 210,000 km or 5 years, and the S-tronic/Multitronic gearboxes need careful maintenance. Manual gearbox versions are significantly more reliable. Verify brake servo recall (2012-2014) completed.
Pump failure can contaminate entire fuel system with metal shavings - more- less
The Bosch CP4 high-pressure injection pump is a known weakness in many VAG TDI engines. If the in-tank fuel pump wears out, the CP4 can run dry and fail catastrophically. Metal shavings then contaminate the fuel rails, lines, and injectors. If caught early (pump only), repair costs around €2,500. If the entire fuel system is contaminated, expect €6,000-8,000+ for complete replacement of pump, injectors, rails, and lines. Avoid forcing multiple start attempts if the car suddenly won't start. Use quality diesel and consider fuel additives with lubricity enhancers. More common after 100,000 km.
DPF clogging (city driving)€150 - €1,500
Diesel particulate filter clogs without regular motorway driving - more- less
The DPF needs temperatures above 600°C to regenerate (burn off accumulated soot). This only happens during sustained motorway driving. Cars driven primarily in cities or for short trips will experience DPF clogging. Below 75% blocked: a forced regeneration at a garage costs €90-150. Above 75% blocked: the DPF needs professional cleaning (€150-200) or replacement (€1,000-1,500). Warning light should not be ignored. Regular 30+ minute motorway drives are essential preventive maintenance. DPF typically lasts 100,000-200,000 km with proper use.
S-tronic/DSG mechatronic failure€1,500 - €4,000
7-speed dual-clutch gearbox has known mechatronic unit issues - more- less
The DL501 (0B5) S-tronic gearbox fitted to quattro models has a well-documented mechatronic failure rate. Symptoms include jerky gear changes, limp mode, EPC warning light, sticking in gear, or loss of reverse. Issues typically appear between 60,000-120,000 km. Dealer repair quotes often exceed €6,000-10,000 for complete gearbox replacement. Independent specialists can repair the mechatronic unit for €1,500-3,500. Electromagnetic plate kit replacement costs around €1,300. Ensure transmission fluid is changed every 60,000 km. Manual gearbox models avoid this issue entirely.
Multitronic CVT wear (FWD models)€2,000 - €5,000
CVT gearbox chain stretches, TCU fails on front-wheel-drive models - more- less
Front-wheel-drive A6 C7 models before 2014-2016 used the Multitronic CVT instead of S-tronic. Early versions had reliability issues, though later units improved significantly. Symptoms of wear include jerking at 30-50 km/h, RPM fluctuations, and excessive rolling back on hills. Chain stretch and TCU (transmission control unit) failures are common. Can last 200,000+ km with proper care, but oil changes every 50,000-60,000 km are essential. Aggressive driving, towing, and short trips accelerate wear. Car cannot be flat-towed. Phased out by Audi from 2014-2016 in favor of S-tronic.
EGR valve carbon buildup€250 - €1,200
Exhaust gas recirculation valve clogs with carbon deposits - more- less
Carbon deposits accumulate in the EGR valve over time, particularly with city driving. Symptoms include rough idle, reduced power, increased fuel consumption, and check engine light. On the 2.0 TDI, the EGR is located at the back of the engine, making labor intensive. Professional cleaning costs €200-300. Full EGR valve replacement at an independent shop runs €700-1,200, dealers quote €1,500-2,300. DIY cleaning is possible but requires removal. Using quality fuel and regular motorway driving helps prevent buildup. Typically becomes an issue after 80,000-120,000 km.
The 2.0 TDI uses a timing belt (not chain) that must be replaced. Audi's official interval is 210,000 km, but many specialists recommend 5 years or 150,000 km, whichever comes first. Time-based degradation occurs regardless of mileage. Independent garage cost: €400-600 including water pump, tensioner, and pulleys. Dealer cost: €800-1,200. A snapped belt causes valve-piston contact, turning a €600 job into a €3,000+ engine rebuild or replacement. The EA288 engine has two timing belts (main and oil pump) - both should be replaced together. Check service history carefully.
Fuel injector failure€400 - €1,500
Piezo injectors can clog or fail, especially with poor fuel quality - more- less
Fuel injectors deliver precise fuel amounts to the combustion chamber. Clogging or failure causes rough idle, misfires, poor acceleration, and increased fuel consumption. Individual injector replacement costs €300-400 each (parts + labor). Full set of 4 injectors runs €1,000-1,500 at independent shops, €1,500-2,000+ at dealers. Bosch aftermarket injectors (OEM supplier) cost around €90 each. Often injectors can be cleaned and refitted rather than replaced. Use quality diesel fuel and consider injector cleaning additives. More common after 150,000 km.
Cylinder head gasket (EA288)€1,500 - €3,000
Metal head gasket on post-2014 EA288 engines can fail with aggressive driving - more- less
The EA288 engine (post-2014 facelift) uses a thin metal cylinder head gasket that can fail under aggressive use. Typically occurs after 100,000 km with hard driving, or 150,000-200,000 km with normal use. The gasket design is thinner than ideal and doesn't tolerate sustained high revs well. Symptoms include coolant loss, white smoke, overheating, or oil/coolant mixing. Head gasket replacement is labor-intensive: €1,500-2,000 at independent shops, €2,500-3,000+ at dealers. Not an issue on the earlier EA189 engines.
Water pump/thermostat failure€800 - €1,500
Plastic cooling system components have limited lifespan - more- less
The EA288 engine has a plastic water pump housing with relatively short lifespan. Thermostat can stick, causing overheating or poor cabin heating. Some failures reported as early as 30,000-50,000 km, though most occur between 80,000-150,000 km. Parts cost €350-500 for water pump with thermostat. Labor is significant (6+ hours) due to accessibility. Independent shop total: €800-1,200. Dealer: €1,200-1,500. Often replaced during timing belt service as preventive measure (recommended). Warning signs: temperature fluctuations, coolant loss, poor heater output.
Turbocharger wear€1,800 - €3,500
Turbo can fail after 100,000-150,000 km, earlier if oil service neglected - more- less
The turbocharger typically lasts 100,000-125,000+ km with proper maintenance. Blue smoke from exhaust, whistling noises, or loss of power indicate turbo issues. Worn shaft bearings, seal leaks, or snapped turbine shafts can occur. Turbo replacement at independent specialist: €1,800-2,500. Dealer with OEM parts: €3,000-3,500+. Dealers often insist on new manifold with turbo, pushing costs to €5,000+. Regular oil changes with correct specification (VW 507.00) are essential for turbo longevity. Avoid switching off engine immediately after hard driving - let turbo cool down.
Air suspension failure (if equipped)€600 - €2,500
Air springs and compressor fail on cars with adaptive air suspension - more- less
Cars equipped with adaptive air suspension will eventually need repairs. Air springs crack and leak (rubber bladder degradation), compressor wears out, or valve blocks fail. Symptoms: car sitting low on one corner, compressor running constantly, suspension warning light. Per-spring replacement: €600-1,000. Compressor: €800-1,500. Full system overhaul: €2,000-2,500. Arnott aftermarket springs offer lifetime warranty at lower cost than OEM. Some owners convert to conventional springs (€1,500-2,000) to avoid future issues. Not all A6 C7 models have air suspension - check spec carefully.
Reliable drivetrain, but emissions systems and automatics need attention
The 2.0 TDI engine itself is robust and can exceed 350,000 km when well-maintained. The main risks are the emissions control systems (DPF, EGR) which suffer with city driving, and the automatic gearboxes (both S-tronic and Multitronic) which require diligent fluid changes and can be expensive to repair. Manual gearbox models are significantly more reliable. Budget for timing belt replacement if not recently done, and verify the car has been driven regularly on motorways.
Pre-Purchase Inspection Checklist
General checks
Service history Complete Audi dealer or VAG specialist records essential. Verify timing belt replacement date/mileage.
Tires Check tread depth, age, and uneven wear patterns.
Cold start Must start engine completely cold. Listen for unusual noises, note smoke color.
Body condition Check for rust, accident damage, paint mismatch. Inspect wheel arches.
Test drive Minimum 30 minutes including motorway to trigger DPF regeneration and warm up gearbox.
Specific for this vehicle
DPF status check via diagnostics Use VCDS or dealer tool to check DPF soot loading percentage. Above 50% indicates heavy city use. Above 75% means regeneration or cleaning needed.
Gearbox operation (automatic models) Drive for 20+ minutes until gearbox is at operating temperature. Feel for jerky shifts, hesitation, or clunking. Check for EPC light.
Check for fuel system codes Use diagnostics to check for fuel pressure faults or injector codes that could indicate CP4 pump issues.
Verify timing belt service Check service records for timing belt replacement. If approaching 5 years or 150,000 km and not done, factor €600-1,200 into purchase price.
Cold start smoke test Start engine completely cold. Blue smoke indicates turbo seal wear. White smoke suggests coolant leak (head gasket). Black smoke points to injector issues.
Air suspension test (if equipped) Look for uneven ride height. Listen for compressor running constantly. Check for suspension warning light.
Verify brake servo recall completed (2012-2014) Cars built Jan 2012 to Aug 2014 may have defective brake servo diaphragm. Contact Audi with VIN.
Check transmission fluid service history S-tronic/Multitronic require fluid changes every 60,000 km. Missing records is a red flag.
Recalls and Technical Service Bulletins
Brake servo diaphragm (Jan 2012 - Aug 2014)Verify completed
Airbags and seatbelt tensioners (May 2016 - Oct 2016)Verify completed
Dieselgate software update (EA189 engines)Check if applied
Coolant recirculation pump (V50) - TSBKnown issue
S-tronic jerky downshift - TSB software updateCheck for symptoms
Contact Audi with the VIN to verify all recalls have been completed. The brake servo recall is particularly important for 2012-2014 models. EA189 engines (pre-facelift) should have the dieselgate emissions fix applied.
Warranty Status
Factory warranty (2 years)Expired on all C7 models
S-tronic extended coverageCheck with Audi dealer
Dieselgate extended warranty (EA189)May still apply - check with dealer
All A6 C7 models are outside their original factory warranty. For EA189-engined cars that received the dieselgate fix, some extended warranty coverage may still apply to emissions-related components. S-tronic gearboxes may have extended coverage in some markets. Contact Audi dealer with VIN to confirm any remaining coverage.
This report is for informational purposes only and does not constitute professional advice. Estimates may be inaccurate. Always have a qualified specialist inspect the vehicle before purchase. We accept no liability for decisions made based on this information.