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Car Reviews  

Audi A6 (2004 - 2011)

Last updated 7 March 2014

 
4

What's good

5 star NCAP crash test rating, 4 star child protection.

Voted first 'World Car of the Year' in February 2005.

What to watch out for

Centre rear seat only really suitable for children plus only 1 star in NCAP pedestrian safety test.

Reports of engine vibrations from 2.0 TDI manuals after around 30,000 miles, apparently caused by "melted injector seals" from using the wrong fuel.

Some readers have reported as little as 1,000 miles a litre of SLX oil (at £13 a litre) from the otherwise excellent 3.0 V6 TDI.

Seemingly widespread problem with dual mass flywheels on A6 2.0 TDI which causes stalling. These can start to separate and the clutch can fail by 45k miles requiring expensive (£1200) replacement.

Also a problem with 2.0 TDI Multitronics stalling. Engine emissions system does not seem to be compatible with the engine braking provided by the latest Multitronics on descents. In November 2007 Audi software programmers were still scratching their heads.

Early 2.0TDIs PD 140s and PD 170s with balancer shafts have a chain drive to the oil pump and the chain drive can eventually snap. Later cars have a hexagonal shaft positive drive to the oil pump that is also a problem. Failed oil pump drives totally wreck the engines and if the car has not been 100% Audi maintained, Audi will not pay.

The oil pump is driven from a balancer shaft via a short hexagonal shaft. The peaks of this hexagonal shaft locate in six corresponding but minute grooves machined within the otherwise circular-bored oil pump drive shaft. Thus, the oil pump drive relies entirely on an interference fit of little more than 0.010" along the peaks of the hexagonal shaft. After about 50,000 miles, the shaft can round off, resulting in a totally destroyed engine and turbo, plus a bill of up to £9,000.

If the danger is known and the oil pump is removed by the garage in good time, a new replacement pump will cost over £500, plus the labour etc to remove and refit it. However, it is also possible to save the old pump and modify the drive at a fraction of the cost of a new one. Many local machine shops already have numbers of these pumps in for such rectification, the drive shaft of each having been on the point of rounding off.

The non balancer shaft BKD, AZV and BMN 2.0 engines (which found their way into the 2.0 PD Octavia, A3, Golf, and various SEATs) used a chain driven oil pump very similar, but not identical, to the old 1.9 130hp PD engine. This never seems to give any problems. It's the balancer shafts that cause the problems on the 'posher' VAG 2.0 PD diesels eg Passat, A4, Superb.

This 2.0 PD differs from the 1.9 in having twin Lanchester balancing shafts which contra-rotate at 2x crank speed. The first engines used a chain drive which was a complete disaster and the later engines a gear drive. All 2.0 PD got the geared drive towards the end of 2005.

The problem with the 2.0 PD engine is the drive from the slave balancer shaft to the oil pump, which is a piece of 6 AF hex bar which has inadequate engagement depth with the grooves in the slave shaft. It's the torsional oscillations caused by the balance shafts which destroy the oil pump coupling (the 6mm AF bit of hex) and the chain drive to the balancer shafts before the gear driven systems came out, though these still give problems with the hex key rounding.

The problem is with lack of concentricity of the drive socket into which the drive rod/hex fits. Chacking shows that all the drive sockets in the failed units were off centre by at least 0.1mm. All the replacement balancer units were dead centre and have not led to a repeat failure. Some replacement balancer units have now done 100k+ miles.

You will get this problem at some point if you have a 2.0TDi WITH balancer shafts. If your 2.0TDi does NOT have balancer shafts, you will be ok. If you fit the lastest balancer shaft/ pump assembley from VAG it will more than likely cure the problem for life as they have made the hex longer and centered it all properley.

CR engines are safe. Anything before that..Audi/VAG wont say exactley when they started to fit the units that actually work properly.

Fuel gauges suffer a fault of the needle stuck on empty when the tank is full (software upgrade required) and the parking brakes are intermittently not releasing, again requiring software upgrade.


Report of leaks through the pollen filter seal into the cabin.

29-1-2011: One reader's experience of A6 2.0TDI Multitronic: "I bought my A6 from Lincoln Audi with 5k on the clock today it has 112k. I have had problems with the car and spent over £3,000 in the past 6 months on DPF, into the garage 3 times before they gave up and changed it with no guarentee it would not happen again. Only last week Oil Pump Siezed and also took out Turbo. I was originally quoted £1600 for the turbo but after haggling and stating my case they charged me £770. the question is I paid £840 for the Oil pump with 10% goodwill. Perhaps I shouldn't complain but these cars should do at least 200k before major component failure thats why we customers pay all that extra money. Having collected my car today there was a note attached to the £2,022 bill stating that the dual mass flywheel is worn and should be replaced at a further cost of £1,099. My previous car was also purchased from Lincoln Audi and was an A6 2.0ltr Turbo Manual and after 15000 miles the Dual Mass Flywheel Seized up. Fortunately for me it was under warranty."

14-3-2011: 3.0TDI V6 quattros prone to water pump failure and also prone to losing coolant from the water cooled EGR valve.

29-7-2011: Timing chains of 3.2V6 petrol engines can fail under Longlife service regime, so much wiser to switch to 10,000 mile oil service intervals.

15-2-2012: Complaint of repeated timing chain failures on 3.2V6 FSI petrol engine.

21-2-2012: Swirl flap motor failure in both inlet manifolds of 2006 2.7TDI V6, and a quotation by the Audi dealer of £1,122 to replace.

25-7-2012: Oddball fault with 2007 A6 2.0TDI Multitronic, sometimes mistaken for a problem with the DMF. EGR valve can break (weld snaps clean off) resulting in loss of power and a noise.

22-9-2012: Rear dampers seem to be failing on 3.0V6 TDI quattros and Audi dealers ask £750 a side to replace them.

31-12-2012: Complaint of repeatedly warped front brake discs on a 2 year old A6 Avant 3.0TDi Tiptronic Quattro. Each set started to judder after around 3,000 miles and required replacing.

26-1-2013: On 2.7V6TDI, individual inlet manifold swirl flaps can break (but yet to hear of one being ingested by the engine). Audi is developing a fix so the whole inlet maifold does not have to be replaced (see 21-2-2012).

25-2-2013: Usual oil pump failure in 60k mile four and a half year old 2.0TDI Avant, leading to turbo failure due to oil starvation. But because the car had been Audi maintained all its life, all fixed for £1,000, after contributions from Audi and the dealer.

19-10-2013: Repeat oil pump drive failures on a 2008 A6 2.0TDI, first time in November 2012 and Audi denied liability due to independent servicing. Repair cost £3,500 at an independent garage. Owner took out an RAC Gold Warranty in January 2013. Then when oil pump failed again 30,000 miles later the RAC refused the claim on the grounds of 'manufacturing' defect.

25-10-2013: Another report of jerky, uneven running of 2006 2.0TDI around 2,000rpm. What had happened was that the EGR motor was ok but the vane attached to the motorised spindle had gone right through the vane. Hence the engine management didnt see an issue as the motor was working by turning the valve spindle but the vane had the small spindle right through the middle and didnt turn at all, hence the mal function of the engine with no errors on the electronic record. New EGR and power is back to like new.

Recalls

November 2005: Safety recall over problem with airbag trigger system software. Further problem over connecting the cars online to Germany for the updated software download.

28-9-2011: VOSA Confirmation of Injectors Recall.

Thank you for notifying Vehicle & Operator Services Agency (VOSA) of theproblems experienced with your vehicle. I can confirm theinvestigation into this fault is now complete.

Following detailednegotiations between VOSA and the vehicle manufacturer, VW-Audi Group (VAG) has agreed to replace all the injectors originally fitted to VAG group vehicles.

If any of the original injectors has already been replaced, VAGwill reimburse customers who have paid for this work themselves even if thework was completed outside of their authorised network.

If your vehilce is within the range of vehilces affected then all fourinjectors will be replaced free of charge.

To progress repairs and/or obtain a refund you should now contact the relevant VAG Customer Service Centre. Ifnecessary, they will arrange to have your vehicle inspected at anauthorised repairer free of charge. The contact telephone number you need to ring is 0800 0833914 and ask to speak toJenny Boyd or Stefan Elliott.

VOSA will continue to work closely with the VW-Audi Group to ensure that this issue is concludedas swiftly as possible.

31-12-2011: Apparently, all VAG models with the 2.0TDI engine from around 2005 fitted with Siemens peizo injectors are subject to a recall which involves replacing all the injectors FOC. Job takes around 3 hours. A short circuit within the injectors causes the fuel system to shut down and engine cuts out.

28-1-2012: Manufacturer recall to replace Siemens Piezoelectric injectors of 2006 - 2009 2.0 TDI BMN engines. All the injectors from the the 2.0 TDI PD engines that use piezoelectric Siemens injectors and Siemens ECUs are affected by this problem. The most problems are on the Passat BKD 2.0 TDI 140HP. No problem from 2009 and the introduction of the common rail 2.0 TDI engine (CEGA).

Unknown date: TSB relating to the EGR and EGR Cooler of 2.0TDI. A weld snaps, rersulting in loss of power.

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