Audi A4 (B7: 2004-2009)

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 and 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, but this is not related to the clutch pack update. The seven-speed software was implemented in the Audi A4 (B7) from the start of production. 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 100k 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 transmissions in the Audi A4 (B7) have seven virtual gears, while the Tiptronic has six gears.

• The way these two transmissions operate is different. You can see the gear changes in the Tiptronic if you look at the RPM gauge, while the Multitronic is stepless in “Drive” mode. In “Sport” mode, it will pretend to have seven gears and will behave just like a regular automatic transmission.

• 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.

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.

1.8 Turbo 20v – short-lived ignition coils

Dead ignitions coils are a typical problem with the 1.8T 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 10k miles. As I see it, this was a big mistake.

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 oil is used and replaced regularly, the 1.8T should have no issues with engine sludge. The 1.8T engines in the B7 were filled with decent oil from the start, so you shouldn’t have too much trouble finding one without any sludge.

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

2.0 FSI / TFSI (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 TFSI or FSI engine can be 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 TFSI & 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.

FSI & TFSI engines – 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 gases from the combustion chamber is blown past the piston rings into the crankcase. These gases 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 gases 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 TFSI and 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 and TFSI engines are happiest to do long trips and they should be revved up regularly to 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 and TFSI 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.

Timing chain spaghetti

The timing chain system introduced by Volkswagen Group in all their “V” engines around 2004 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 risky second-hand purchase.

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. Other “V” engines will be similar.

Have a look at the video below. This is what the timing chain spaghetti in the 3.0 TDI looks like.

 

Click here to learn more about timing chains and how to check them when buying a second-hand car. In any case, the timing chain system should not be showing any symptoms of problems in the Audi A4 you are planning to buy if you want to avoid massive service costs.

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.

There are some differences between the Audi “V” engines and some are better than others. Here’s a brief description of what to look out for:

3.2 FSI

There have been cases of problems with the top two chain tensioners. As usual, the symptoms of a failing tensioner include rattling noises at start up or the “Check Engine” light in severe cases. If left untreated, a loose timing chain may jump a couple teeth, which often results in broken parts – the usual “failed timing chain” horror story.

Thankfully, the top two tensioners are the easiest to replace and can be accessed without removing the engine from the car. In my opinion, you may get away with replacing just them when the chains become loose, rather than the entire timing system (chains, tensioners and chain guides). Will you take a gamble?

 

4.2 40v (Audi S4)

This engine was the first one to be fitted with the timing chain spaghetti. In my opinion, this engine is the worst one of the lot because of plastic chain guides that may fail prematurely (at around 100k miles).

Another two problematic components that I can think of are the camshaft adjusters and the chain tensioners. I think you should avoid these engines unless you can find one that had the timing chain guides replaced recently.

 

4.2 FSI (Audi RS4)

The 4.2 FSI is based on the older 4.2 40v engine used in the Audi S4 (B6 and B7). The good news is that the chain guides are now metal and much stronger. The chain tensioners also seem to be better than in the 3.2 FSI engines. This engine is the best (or the least worst) choice, in my opinion.

 

2.7 & 3.0 TDI

A used V6 TDI may suffer from the same top tensioner problems as the 3.2 FSI. The good news is that the tensioners were updated in 2007. The bad news is that some cars produced in 2007 can still have the older parts. I’m talking about 2008 model year cars (produced in 2007). Basically, it’s difficult to tell which B7 cars have the updated parts and which don’t. In any case, the 2008 model year has a chance to have them. Will you take a gamble?

 

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 it.

3.0 & 2.7 TDI – leaky fuel injectors

The 3.0 TDI appeared in 2004 and was the first engine made by Volkswagen Group to utilize Common Rail injection. “Pumpe Düse” injectors were scrapped in favour of Common Rail technology because of tightening emissions regulations (PD does not work well with Diesel Particulate Filters). Bye, bye Pumpe Düse. Hello Common Rail.

Some of the early Common Rail V6 TDI engines were fitted with flawed piezo-electric injectors that could wear out prematurely and over-fuel the engine. The extra fuel from such “leaky” injectors does not burn fully and may be visible as white smoke coming out the exhaust after a 5-10 minutes standstill with the engine idling.

The white smoke may also appear after a cold start. Another symptom, which is not immediately visible, is rising engine oil level because of the unburnt fuel diluting the oil. 

The injectors were updated a few times and all the issues were finally resolved in 2006. Hopefully, any faulty injectors would have been replaced by now in cars manufactured before 2006.

However, leave the car you are planning to buy idling for 10 minutes and look out for any smoke. Better safe than sorry. If the car was manufactured in or before 2006, find out if the injectors have been replaced.

Here’s a video of a smoking 3.0 TDI:

 

TDI PD engines – 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).

2.0 TDI PD – “porous” cylinder heads

When first released, the 2.0 TDI engine was not a very good unit, in my opinion. There have been cases of unexplained coolant loss in some of the early 2.0 TDI engines. Those engines were fitted with revision “A” cylinder heads. 

I believe that porosity was present in these heads, which made them susceptible to developing micro-cracks and allowing the coolant to enter the combustion chambers.

Symptoms of a leaky cylinder head are as follows:

• coolant loss with no external leaks

• difficulties starting the engine after a long standstill (coolant accumulating in the cylinders and possible mild hydrolock)

• white smoke after starting the engine (coolant vaporized during combustion)

The cylinder heads were updated a couple times – revision “B” wasn’t much better as I see it, and revision “C” managed to solve the problem. The revision letter can be found on the cylinder head (upside down) and can be checked once the plastic engine cover is removed.

Revision “C” was introduced in 2006, therefore, I recommend avoiding cars produced before 2007 unless the cylinder head has been updated to revision “C”.

Production of the 2.0 PD engines stopped in 2008 as they were superseded by Common Rail engines, which are free from this problem.

Here’s a video showing engine starting issues due to coolant accumulating in the cylinders:

 

In my opinion, the BMM engine variant is the saving grace of the early 2.0 TDI engines. The BMM is an 8-valve version of the 2.0 TDI engine that was available in cars produced between 2005 and 2008. This 8-valve engine is actually closely related to the older 1.9 TDI. The potential cylinder head leaks do not affect this engine.

It gets a bit confusing when you try to determine which cars have the BMM variant. That’s because it has 140 PS and identical torque as the 16-valve 2.0 TDI. 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 sticker on the timing belt cover.

The engine code can also be found on a sticker under the boot carpet. Another indicator is the engine cover, which is different in the BMM variant.

Keep in mind that the turbo fitted to the BMM engine is a bit small so it tends to run pretty hot. If you want it to last, use good quality synthetic oil and don’t slack on oil changes. Also, let the turbocharger cool down before turning the engine off. Be aware that all BMM engines have Diesel Particulate Filters (DPF).

2.0 TDI PD – oil pump drive inspired by Ikea

The 2.0 TDI cars with longitudinal engines, like the Audi A4, are fitted with balance shafts that smooth out the engine vibrations. In such engines, the oil pump is integrated with the balance shaft module that sits at the bottom of the engine. The balance shafts are driven off the crankshaft by a short timing chain. The oil pump is then driven off the balance shafts through a hexagonal shaft.

Imagine a 6mm Allen key driving the oil pump. The hex shaft in these engines is just one millimetre thicker than the 5mm hex keys Ikea provides to assemble their furniture. Now, imagine what happens when the hex shaft that drives the oil pump rounds off…

The oil pumps in the 2.0 TDI can fail in two ways:

1. The hex shaft rounds off and starts slipping. The oil pump then stops delivering oil to the engine, which can seize if the vehicle is not stopped immediately. While rounded Ikea hex keys prevent you from putting together your new TV stand, a rounded off 2.0 TDI hex key will kill your engine very quickly.

2. The chain drive fails – the sprocket that drives the oil pump loses its teeth when the chain tensioner fails. The end result is the same as above.

There have been cases of both types of failures in the early 2.0 TDI engines. I believe this is because the balance shafts put a lot of stress on the chain that drives them, and the high vibration environment causes the hex shaft, which drives the oil pump, to wear at the edges.

At the beginning of 2006, a gear drive for the oil pump was employed and the hex shaft was strengthened. This fixes both problems – stronger hex shaft and no chain to fail. In my opinion, this is a very good reason why you should avoid cars the 2.0 TDI engines that were manufactured before 2007.

To conclude, here’s some food for thought:

The system used in the 2.0 TDI, as described above, is driven at twice the engine speed. This is necessary for the balance shafts to work. The older 1.9 TDI engines had an oil pump driven at half the engine speed and had no balance shafts. Guess which one is going to last longer…

2.0 TDI PD – injector issues (170 PS version only)

The early 170 PS 2.0 TDI engines were fitted with faulty piezo-injectors made by Siemens. There was a recall for these parts, so hopefully, the vast majority if not all of the bad injectors were replaced by now.

If you are planning to buy a car with the 170 PS 2.0 TDI, find out if it had the fuel injectors replaced. This issue only affects PD engines coded BRD. The later Common Rail units are fine.

Summary of problems & additional information

• The Audi A4 B7 is a heavily facelifted Audi B6 model with a new range of engines available. The production of the B7 sedan and the estate models ended in 2008 while the convertible remained available until 2009.

• You should avoid cars with the Multitronic. Leave the CVT for mopeds and look for a car with the Tiptronic if you like automatic transmissions.

• The 1.8T engine can be tuned for a lot more power relatively easily. Despite being a dated design, the 1.8T is probably one of the best petrol engines available in the Audi B7 chassis.

• 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 TFSI engines. Apart from the risk of buying a car with a worn cam follower, they are decent engines.

• The 3.2 FSI, 4.2 40v or 4.2 FSI: Buying a used car with one of these engines is risky. Because the timing chain system is so complex, buying them second-hand is not advised unless there is documented proof that the timing system was serviced. You don’t want to be the person that has to pay for fixing it. I think that these engines are good when they are new but start becoming risky once they approach around 100k miles. If you are still thinking of buying a car with one of these engines, the 4.2L Audi S4 is the worst choice, while the 4.2 FSI Audi RS4 will probably be the best one (or the least worst). In any case, try to avoid high mileage cars and watch out for any symptoms of timing system wear.

• Carbon build-up is likely going to be an issue with the FSI or TFSI engines at some point, especially if you only drive short distances. To some degree, carbon build-up affects all gasoline direct injection engines that don’t have a dual injection system. What I’m trying to say is that it’s a problem not limited to the FSI or TFSI engines. Other manufacturers faced the same issue.

• The first revision of the 3.0 TDI was not very reliable, in my opinion. Going forward, the injectors were improved in 2006 and the chain tensioners in 2007. It’s difficult to tell which B7 cars have the updated tensioners and which don’t. In any case, the 2008 model year has a chance to have them. However, I still don’t recommend this engine because most of them will be high mileage units by now, and having to replace the timing chain system will make you cry.

• The 2.5 TDI, despite its bad reputation, 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 injectors. The 2.5 TDI engines in the B7 model have all the issues sorted out and they should be much more reliable than the older 2.5 TDI engines used in the Audi A4 (B6).

• There is also the 1.9 TDI PD available in the B7 chassis. It’s a good unit and much more economical than the 2.5 TDI. Just avoid the super-high-mileage cars due to increased risk of camshaft wear in PD engines.

• As for the 2.0 TDI engine family, it’s a bit of a minefield. If you really want one, the BMM engine variant is probably the best choice if you don’t mind the diesel particulate filter (DPF).

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

• Some engines in the Audi A4 (B7) are fitted with timing belts and some use timing chains. Click here to learn more about timing belts and chains.

Petrol engines – specs & performance figures

Diesel engines – specs & performance figures

Petrol engines – technical details

Diesel engines – technical details