Audi A4 (B6: 2000-2004)

Steering system issues

The power steering pump and the steering rack are some of the weak points in a second-hand Audi A4 (B6). Therefore, when buying one of these cars, look out for:

• groaning or whining noises from the power steering pump (often caused by low power steering fluid level)

• play in the steering wheel and noises when turning the steering wheel – check when the car is standing still with the engine turned on

• any leaks from the power steering system – check under the car if possible

Multitronic CVT transmission failures

The Multitronic is a type of “Constant Velocity Transmission”, which uses cones and a drive chain to achieve stepless gear ratio changes. This makes for a very smooth transmission (when it works). Have a look at the video below, which explains how CVT transmissions work.

Apart from their smoothness, another key benefit of CVT transmissions is that they can make the car accelerate while the engine RPM remains constant. This is an advantage because the engine can then operate at an RPM that is most efficient while the car is accelerating. When you floor it, the RPM climbs close to the redline and stays there to get the most power out of the engine.

In theory, the Multitronic is relatively simple and the principle of operation doesn’t have any obvious flaws. However, I would argue that in practice it was hopelessly unreliable – at least the first generation.

There were several revisions of the Multitronic transmissions and these are the key milestones:

2001-2006 – there have been cases of the first-generation Multitragic transmissions suffering from ECU failures, clutch plate issues and excessive internal wear at low mileage.

The first generation had six virtual speeds in manual shift mode. Some improvements were made during the first years of production but that wasn’t enough. As I see it, Audi managed to sort out all the problems only around 2006.

2007 and onward – at this point, the problematic clutch pack was finally upgraded from six plates to seven plates, and the ECU programming was updated. One more virtual speed had been added earlier, making the Multitronic a “seven-speed” transmission. However, the important difference was the clutch pack upgrade in 2006.

2006 was a milestone year, but the most reliable transmissions are likely to be the newest ones as I’m sure Audi made further improvements since 2006. The number of virtual speeds was increased again to eight speeds a couple years later.

It’s not all roses though. Even the updated Multitronic transmissions have a relatively short lifespan – anything above 100k miles is risky and anything above 150k miles is a ticking time bomb.

If you’d like an Audi with an automatic transmission, the Tiptronic is a better choice. The Tiptronic was a conventional automatic transmission used by Audi.

My recommendations:

• First generation Multitronic (2001–2006) – no, just no.

• Updated Multitronic (2007 and onward) – more reliable but still not recommended. The Multitronic is not something you want to own outside of manufacturer’s warranty.

If you are still hell-bent on getting a car with the Multitronic, look out for:

• jerky operation and rough take off (juddering)

• engine revs fluctuating when driving at a constant speed

• prolonged delay when taking off

• vibrations while driving

• when coming to a standstill: car lunging forward or revs dipping down like the engine is going to stall

• any noises from the transmission

• a sensation that the gearbox is slipping

• poor operation when cold (test drive the car when the transmission is cold)

• any weird behaviour in reverse gear

• flashing “PRNDS” letters on the instrument cluster screen (instead of just “D”)

If you want to improve your odds of trouble-free driving with the Multitronic transmission, you should:

• only consider cars manufactured in 2007 and later (updated clutch pack)

• only consider cars that have a perfect transmission oil change history

• avoid the cars with a towing bar (towing with the Multitronic is a bad idea)

• avoid cars that have more than 100,000 miles on the clock

• avoid the V6 and TDI engines (less torque = longer transmission life)

• don’t buy remapped cars

It’s not obvious at first glance if the car is fitted the Multitronic or the Tiptronic because the gear shift knob looks the same. There are a few ways to find out:

• Put your foot on the brake, then put the car into “D”. With your foot still on the brake, move the gear change knob to the right to enter manual shift mode. You will see which gear you are in and how many gears are available on the little screen between the RPM gauge and the speedometer. The Multitronic transmission in the Audi A4 (B6) has six virtual gears, while the Tiptronic has five gears.

• The way these two transmissions operate is different. You should be able to see the gear changes in a car with the Tiptronic if you look at the RPM gauge, while the Multitronic is stepless.

• The Multitronic transmissions were only fitted to front wheel drive cars. If the car has 4-wheel drive (Quattro), it has the Tiptronic. The majority of FWD cars will have the Multitronic but the Tiptronic was fitted to some as well.

Audi A4 Cabriolet – convertible roof

The fabric roof and the hydraulic system are reliable. The roof is operated by six hydraulic cylinders and a hydraulic pump in the boot of the car. Your three main concerns are weather intrusion (fancy name for a leaking roof), hydraulic fluid leaks and just general wear.

The things to check regarding the roof are:

• Check for any dampness in the footwells and carpets. Also, check in the boot underneath the spare wheel.

• The rear window can sometimes become unglued and start letting water in. Check if it is still firmly attached. If it isn’t, it can be glued back so this doesn’t cross out the car, but it is a reason to negotiate the price down. Check if the rear demister works.

• Open and close the roof a couple times to make sure that it works.

• Check the condition of the roof fabric.

• Check the condition of the roof seals. Ideally, they should be lubricated regularly – ask the previous owner about it.

• Check if the level of hydraulic fluid is correct. If it isn’t, then the car may have been neglected or there is a leak somewhere.

• Look for hydraulic fluid leaks.

• Get the car up to 60 mph with the roof closed and listen for excessive wind noise.

• Listen for squeaking or rattling noises while driving with the roof closed.

• Take the car to a high pressure (touchless) car wash and see if any water gets inside the cabin, in the boot or through the rear window.

A word of warning: If you’re not into DIY and you’re not willing to understand how the roof mechanism operates, you may pay for servicing more than you need to.

The roof on the Audi may be reliable but it is still relatively complex and some small things may at some point require fixing or adjusting. If you can’t diagnose or repair these little things yourself, trying to get the roof sorted out at a car repair shop may be expensive. Here’s an example:

One of the common reasons for the roof not working is worn brushes in the motor that operates the hydraulic pump. Brushes are typical components in most DC motors and they cost a couple of pounds. In the Audi A4, they can get stuck occasionally and eventually they will wear out.

You can buy them and replace them yourself (very cheap). You can have someone else do it (still relatively cheap) or you can go to the dealership and tell them that your roof doesn’t open. They’ll probably tell you that you need a new hydraulic pump for £2,000. How situations like this play out depend on your willingness and ability to diagnose simple problems.

2.0 FSI (1st gen. EA113) – cam follower wear

FSI stands for “Stratified Fuel Injection”, which is Volkswagen Group’s direct injection system. The FSI system is based on a high-pressure fuel pump, a fuel rail and solenoid injectors. It is similar to the Common Rail injection used in modern diesel engines but operating at 110 bar instead of 1500+ bar.

The high-pressure pump is driven directly off the camshaft by an extra cam lobe. This way, the rotating motion of the camshaft is converted into reciprocating motion of the fuel pump piston. In my opinion, this is all very cleverly designed with the exception of one small part. This unlucky part is the cam follower.

The cam follower is a little bucket thingy (a flat tappet) that sits between the pump and the cam lobe that drives the pump. It rides the cam lobe on a film of oil – it is in constant contact.

The problem with these engines lies in the fact that the cam follower can wear – even to the point of breaking a hole in the centre. The problem is exacerbated by infrequent engine oil changes and use of incorrect oil.

For this reason, buying a second-hand 2.0 FSI engine can be a bit of a gamble if there is no record of cam follower replacement(s). If you unknowingly buy a car with a badly worn cam follower, you are likely to soon replace not just the cam follower but also the camshaft and the high-pressure fuel pump.

Driving with a worn CF will quickly damage both the camshaft and the pump. In my opinion, VW Group should have made the cam follower a 30k miles service item. It is an inexpensive part and replacing it is easy. Usually, there is little or no symptoms of the problem until it’s too late.

The typical symptoms of a worn out cam follower in the 2.0 FSI engines are:

• Engine cutting out when accelerating at high RPM

• Error codes stored in the ECU and glowing “Check Engine” light – at this point serious damage is likely

It’s tough to say how long a cam follower will last. Some look fine after 70k miles and some are completely worn out after 50k miles. It all depends on the oil change intervals, oil quality, manufacturing tolerances and driver habits.

Cars that failed under warranty, as well as 2008 cars, are likely to have an updated camshaft (revision B), which should make the system last longer.

The bottom line is this – because all the EA113 engines are likely high mileage ones by now, look for cars that had the cam follower replaced or cars owned by people who are aware that the cam follower must be kept in good condition and should be inspected regularly.

If the seller agrees, you could also take the car to the dealership for a cam follower inspection. It is fairly straightforward to check for someone experienced.

2.0 FSI (1st gen. EA113) – carbon build-up

Direct petrol injection systems, like the FSI, are prone to carbon build-up on the engine intake valves. Excessive carbon build-up can reduce power, increase fuel consumption and make cold starts difficult. The “Check Engine” light may appear too.

Carbon build-up is a common problem for many direct injection petrol engines as the fuel is no longer injected into the intake manifold where it has a chance to wash away any carbon build-up from the intake valves.

The carbon deposits come from the Crankcase Ventilation System (CVS), which is connected to the intake. It’s a common design in most engines. In any piston engine, a small portion of the gasses from the combustion chamber is blown past the piston rings into the crankcase. These gasses contain oil vapour (hydrocarbons) and combustion by-products (more carbon).

From the crankcase, they are fed back into the engine through the intake manifold, where they form deposits. Also, there is the Exhaust Gas Recirculation (EGR) valve that redirects a portion of exhaust gasses back into the engine intake (even more carbon).

With direct injection, as the name implies, the fuel is fed directly into the cylinders. Detergent fuel additives don’t really work in the FSI engines as the injected fuel doesn’t go over the intake valves like in the older manifold fuel injection systems. Therefore, it doesn’t have a chance to wash away the carbon deposits.

Sooner or later, all FSI engines will have some carbon build-up. It is inevitable, Mr Anderson.

It seems that the main contributing factor that accelerates carbon build-up is driving short distances. If the engine rarely reaches a high enough temperature, the carbon deposits will not be burned off and they will start accumulating. Driving like an old lady doesn’t help either (no offence to any old ladies!).

The FSI engines are happiest to do long trips and they should be revved up regularly to help clean the gunk from the intake valves.

If the build-up becomes severe, the only option is manual cleaning. This requires the intake manifold to be removed. To conclude, gasoline direct injection is more efficient and will save you some money at the gas station. However, I feel that you’ll probably have to give it back paying for carbon cleaning – a zero-sum game, I tell you.

If you do lots of motorway driving and like to drive hard, you’ll probably be okay for some time. Many FSI engines reach a relatively high mileage before developing any problems related to carbon build-up. However, if you’re doing lots of short trips, then carbon cleaning may be on the horizon.

As a side note, there is a way of eliminating carbon build-up in direct injection engines. It requires additional fuel injectors that can wash off the gunk from the valves – a dual injection system. VW Group implemented this solution in 2011 with the introduction of the third generation of the 2.0 TFSI engines.

1.8 Turbo 20v – short-lived ignition coils

Dead ignitions coils are a typical problem with the 1.8 turbo engine. The ignition coil is a device that generates high voltage for the spark plug to initiate the combustion in the engine. In the 1.8T, there is one ignition coil per cylinder (coil-on-plug) and it sits on top of the spark plug. Each ignition coil costs around £40 each, and they can be replaced individually when they fail.

The symptoms of a faulty ignition coil are as follows:

• rough running

• engine hesitation

• loss of power

• possible “misfire” error codes

• excessive smoke from the exhaust

If you want to save some money, don’t buy the ignition coils at the dealership. Instead, you can get them cheaper online. BERU is the original equipment manufacturer for Volkswagen and Audi.

Overall, the ignition coils are not a massive problem as they are relatively easy to replace and not very expensive. Below is a demonstration of coil pack replacement.

1.8 Turbo 20v – sludge and dino oil

The 1.8T engine is hard on engine oil because of its small oil capacity and because the turbocharger generates a lot of heat. There have been cases of the early 1.8T engines developing oil sludge that could block the oil pump pickup and starve the engine from oil.

The manufacturer’s original recommendation was to use conventional oil, also known as dino oil, and replace it every 10,000 miles. As I see it, this was a big mistake.

Usually, a drop in oil pressure would first ruin the bearings in the turbocharger and then the camshaft bearings. In severe cases, such as continued driving despite a low oil pressure warning, the engine could seize.

In 2004, Volkswagen Group revised the maintenance manual to use only synthetic oil in the 1.8T. Synthetic oil has much better high-temperature stability and doesn’t sludge up nearly as easily as mineral oil. Provided the correct synthetic oil is used and replaced regularly, the 1.8T should have no issues with engine sludge.

On one hand, the 1.8T is a robust engine capable of reaching a very high mileage, on the other hand, it can die prematurely if not maintained properly. If you’re looking to buy a car with the 1.8T, look for one with documented oil change history using synthetic oil. A 2004 Audi A4 would be ideal.

P.S. Dino oil is just a name that stuck. Dino oil (mineral oil) comes from fossils, but not dinosaur fossils.

3.0 30v V6 – camshaft wear

There have been cases of premature camshaft wear in the 3.0 30v engines. It seems to me that this issue mainly affects cars made in 2002 and 2003. However, it could still happen to any 3.0 30v with poor maintenance history. The typical symptom of worn cam lobes is a ticking noise. In severe cases, the engine will run poorly and misfire.

I think that you should avoid cars made in 2002 or 2003 and the ones without a history of regular oil changes. When you find a car with the 3.0 30v V6 that you would like to buy, listen for any ticking noises coming from the engine. Listen to the engine when it’s cold and then check it again when it has warmed up.

Audi S4 4.2 40v – timing chain spaghetti

The timing chain system in this V8 engine is an engineering abomination, in my humble opinion. There are four timing chains and four chain tensioners.

Generally, when a timing chain is used, the intention is for it to last the “lifetime” of the engine. That’s probably why VW Group decided to put the timing chains at the rear of the engine, which makes it impossible to service them without removing the engine from the car.

As I see it, this systems is too complex to assume that nothing will go wrong over the “lifetime” of the engine, which makes it a very risky second-hand purchase.

Apart from just being overly complex, there have been cases of cracked plastic chain guides in the Audi S4 (B6). It seems that the sweet spot, or rather the bitter spot, for chain guide failures is around 100,000 miles. On top of this, I can think of another two components that fail too early in my opinion – the camshaft adjusters and the chain tensioners.

Just so you know, replacing all the key components in the timing chain system of the 4.2 40v engine costs is in the vicinity of £2,000 in an independent car repair shop. If you take the car to the dealership, you may be looking at £4,000.

Here’s what a broken timing chain guide looks like:

If you are going to buy a second-hand car with this engine despite my warnings, listen for any chain rattle during a cold start. Ideally, there should be none. If there is any rattle, it must not last longer than a second. Any longer than that and you may have to replace some parts in the near future.

Also, make sure there is a record of regular oil changes. Poor maintenance will accelerate the wear on the timing chain system as it is lubricated by engine oil.

Finally, the “Check Engine” light must not be on, and it’s worth connecting to the car through the OBD port to check if there aren’t any error codes related to camshaft timing stored in the car’s memory.

I’ve always wondered why VW Group designed such a complex system. I think that it might have something to do with the chain length. Generally, a shorter timing chain lasts longer because it’s less susceptible to stretching. Also, the fewer gears a chain has to go over, the longer it will last.

My theory is that VW Group decided not to use a single, long timing chain, which they thought would stretch too quickly. Instead, they decided to fit the engine with four short chains, which in theory should last longer than a single, long one.

In practice, I think that they added too much complexity to achieve this goal. These engines are good for a few years after leaving the factory, but as they get older and rack up the miles, the risk of having to replace parts in the timing system increases. You don’t want to be the person that has to pay for this.

2.5 TDI V6 – camshaft wear & EDC failures

Where do I start… Finding a 2.5 TDI engine without faults is like walking through a minefield, in my opinion. Okay, grab my hand and let’s go.

A typical problem with the early 2.5 TDI engines is premature camshaft wear. I believe that the primary cause was insufficient hardness of the cam lobes. The wear would then be accelerated by long oil change intervals and when unsuitable engine oil was used.

In 2001, the valvetrain was updated and the longevity of the camshafts improved somewhat, but with poor maintenance, the valvetrain components can still wear. Let’s not stop here though, we’re not out of the minefield yet.

In my opinion, even the post-2001 valvetrain components are not up to the job. Therefore, buying a second-hand car with one of these engines is a gamble. Unless you remove the valve covers, you cannot be sure that the four camshafts are in good shape. Only when badly worn, the problem becomes noticeable (loss of power and poor starting).

Another typical problem of the early 2.5 TDI engines was the reliability of the VP44 injection pump. There have been cases of the pump dying without a warning because of a problem in the Electronic Diesel Controller (EDC). The EDC was improved in 2001 and the newer pumps are generally fine.

In late-2003 (2004 model year), roller cams were introduced and this finally solved the problem of camshaft wear. Audi got it right just before the production of the 2.5 TDI stopped. Roller cams were then used in the 2.7 and 3.0 TDI engines, which have no issues with camshaft wear. The 2.5 TDI engines coded BAU, BCZ, BDG and BDH have rollers cams.

To be sure which engine is in the car you are planning to buy, you can remove the plastic engine cover and read the engine code from the engine block. The engine code can also be found on a sticker under the boot carpet. The boot sticker is easier to check, but it is not 100% reliable. You can let go of my hand now…

Conclusions

• I think that the 2.5 TDI was a pretty terrible engine when it was first released. Over the years, it was improved to a point where buying a second-hand car with one is not akin to shooting yourself in the foot. If you’d like a car with the 2.5 TDI, you should only consider engines coded BAU, BCZ, BDG or BDH. These will have all the issues corrected and should be quite reliable.

• Replacing the timing belt in this engine is more complicated than usual so expect to pay more too. The thermostat is in a stupid location, so it’s worth replacing it at the same time as the timing belt.

1.9 TDI PD – camshaft wear

PD stands for “Pumpe Düse“, which is Volkswagen Group’s brand name for unit injector technology used in their diesel engines. Here’s how it works: each fuel injector is a stand-alone unit, integrated with its own miniature fuel pump that is actuated by the camshaft.

The camshafts in PD engines have extra cam lobes used only by the unit injectors to generate high fuel pressure. Therefore, the injector timing is roughly linked to the camshaft timing while the precise moment of injection is then determined by an electric solenoid valve inside the PD injector.

You can recognize a PD engine by the lack of high-pressure fuel lines going to the injectors (the high pressure is generated directly in the injectors).

The extra cam lobes used by the unit injectors take a lot of space on the camshaft. Therefore, there is less room for the intake and exhaust cam lobes, which have to be narrower. This design puts a lot of stress on these cam lobes.

The oil film is what keeps them from wearing out and VW Group engineers are very specific about the oil requirements for their PD engines. Therefore, to avoid camshaft wear, it is essential that the correct oil is used and replaced regularly. With proper care, PD engines can last a long time.

The tell-tale sign of a badly worn exhaust cam lobe, which can wear if neglected, is a popping sound coming from the engine bay or the exhaust. Also, look out for any kind of knocking noises coming from the engine. The “Check Engine” light may come on in severe cases of camshaft wear.

All of this is applicable to the entire family of PD engines, but it seems to me that the most severely affected variant is the 1.9L 99hp engine used in VW Jetta (engine code: BRM).

Summary of problems & additional information

• Avoid the Multitronic in the Audi A4 (B6). In my opinion, the first generation of these transmissions had serious issues. Leave the CVT for mopeds and look for a car with the Tiptronic if you like automatic transmissions.

• Some used Audi A4 models develop problems with the steering system. When buying one of these cars, make sure there are no leaks, no noises and that there is no play in the steering wheel.

• If you’re trying to make up your mind whether to get the 2.4 V6 or the 1.8T, both engines are good choices. Their power output is similar but the 1.8T can be remapped for a lot more. The 1.8T will also be cheaper to insure and gets a bit better gas mileage. On the other hand, the 2.4 V6 sounds a lot better, and it is slightly less demanding maintenance-wise. At high mileage, there is no turbo to worry about and it doesn’t eat ignition coils like the 1.8T. The timing belt replacement in the 2.4L will be a lot more expensive than in the 1.8T though. When replacing the timing belt in the 2.4 V6, it’s worth replacing the thermostat at the same time.

• The 3.0 V6 is similar to the 2.4 V6 engine with a couple of differences:

  • The thermostat is in a somewhat more reasonable location – you don’t have to remove the front of the engine to get to it. I guess Audi engineers deserve a pat on the back.

  • All camshafts are driven by the timing belt. There are no camshaft chains like in the 2.4. The variable valve timing system in the 3.0 is slightly more complex.

  • The ignition system uses individual coil-on-plugs instead of a coil pack.

  • In my opinion, the 2.4 V6 is the better choice because the 3.0 V6 is more susceptible to camshaft wear and its VVT system is more complex.

• The 1.6 16v is the least complex, cheapest to maintain, and the most boring option. The 2.0 20v is less boring but may develop a drinking problem. Because of high oil consumption in some of those engines, it’s better to choose a different model, for example, the 1.8T.

• Watch out for worn cam followers (and camshafts, and pumps) in the 2.0 FSI engines. Carbon build-up is likely going to be an issue at some point, especially if you only drive short distances. I think that it’s best to avoid these engines as there are better options available in the B6 chassis. cough…1.8T…cough

• Timing chain system service in the 4.2 40v is inevitable and very expensive. I can’t recommend this engine unless you can find one that had a full timing chain system service recently (new chain guides, chains and tensioners). You don’t want to be the person who has to pay for this.

• In my opinion, the 130 PS 1.9 TDI PD (engine codes ASZ, AVF, BLT, AWX) is one of the best diesel engines Volkswagen ever made. It combines all the features desirable in a diesel engine – excellent economy, reliability and decent power. It can also be remapped to around 170 PS with no hardware changes. Good service history is a must when buying a TDI PD engine. Also, avoid the super-high-mileage cars due to increased risk of camshaft and injector wear.

• As for the 2.5 TDI, if you can find a BAU, BCZ, BDG or BDH engine (2004 model year), it should be nearly as reliable as the 1990s 1.9 TDI with a distributor pump. The 2.5 TDI is one of the last “old-school” mechanical diesel engines. It’s a direct injection engine with all its benefits, but it uses mechanical solutions to achieve this – a distributor pump and mechanical (spring) injectors. It’s the same technology as the TDI engines that came before VW Group introduced Pumpe Düse injection. The V6 TDI sounds better than the 1.9 TDI and because of its bad reputation, you might be able to get a good deal.

• Follow this link for an article that might help you decide if a modern diesel engine, like the 1.9 TDI PD, is the right choice for you.

• Keep in mind that Audi is a manufacturer of high-performance luxury cars. High performance usually goes hand in hand with increased complexity. When things go wrong, you can expect the servicing costs to be above average.

• All engines in the Audi A4 (B6), apart from the 4.2 V8, are fitted with timing belts. Read more about cambelts and timing chains.

Petrol engines – specs & performance figures

Diesel engines – specs & performance figures

Petrol engines – technical details

Diesel engines – technical details