B7 Audi A4
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The 7 Most Common B7 Audi A4 Engine Problems

Chandler Stark

Meet Trey

Trey is an automotive enthusiast and has a huge passion for Volkswagen and Audi vehicles of all kinds. His enthusiasm started with the MK5 GTI, and he has massively expanded his knowledge over the years. When Trey is not delivering high-quality and in-depth content, we can usually find him working in his garage on his modified Genesis coupe. Trey created VW Tuning several years ago, and he is the primary visionary behind the content.

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Audi introduced the Third Generation, B7 A4, in 2004 which was pretty much a heavily facelifted version of its predecessor, the B6 Audi A4. Production started in 2004 and ran through 2009, and was arguably one of the most popular A4’s Audi has put out yet. Some differences from its predecessor include updated steering and suspension settings, new engine choices, upgraded navigation system, and chassis electronics. The B7 Audi A4 was built on the VGA PL46 platform.

Like many other Audi’s and VW’s, there were many engine options to choose from when it came to the B7 Audi A4. The most popular engines in the US were the 2.0T and the 3.2L V6. The 2.0T FSI puts down 200hp and 207lb-ft of torque, while the 3.2L V6 naturally-aspirated puts down 252hp and 243lb-ft of torque. The transmissions that were available on these engines were a six-speed manual or five-speed automatic.

Before getting into the B7 Audi A4 problems, we want to state that this post will focus on the 2.0TFSI engine. With that said, please make sure any of the parts listed below fit your vehicle. If you need assistance with parts or DIY guides for other engines, please reach out in the comments!

Common B7 Audi A4 Engine Problems

  • Ignition Coil Pack and Spark Plug Failure
  • Carbon Build-Up in the Intake Valves
  • Excessive Oil Consumption
  • PCV (Positive Crankcase Vent) Valve Failure
  • HPFP (High-Pressure Fuel Pump) Failure
  • Defective Fuel Injectors
  • Premature Cam Lobe Wear

1. Ignition Coil Pack and Spark Plug Failure

Ignition coil packs and spark plug failure are common in many Audi and Volkswagen engines, especially in engines that have been modified. Both components are crucial in the engine combustion process. Ignition coil packs transform the lower voltage, supplied by the battery, into higher voltage for the spark plugs. Then once the spark plugs are essentially charged, they will create a spark/ignition in the combustion chamber which makes the engine produce power.

When either of these fail, there will predominantly be a CEL or MIL illuminating followed by engine misfires. Normally, coil packs and plugs fail due to normal wear and tear or modifying an engine. If you are planning on modifying the engine, we highly advise getting both upgraded coil packs and spark plugs because the factory ones aren’t made to sustain much more power than the OEM intended for them. A good general rule of thumb is to change both around 60,000 miles.

Symptoms of Ignition Coil Pack/Spark Plug Failure:

  • CEL/MIL illuminating with P0300 – P0304 fault codes
  • Engine misfires
  • Rough idle
  • Rough engine performance
  • Engine stalls
  • Trouble starting the engine
  • Engine surging

Ignition Coil Pack & Spark Plug Replacement Options:

When replacing ignition coil packs or spark plugs, it is important to change all of them, one per cylinder, at once. The reason we suggest this is because typically they will go out around the same time, which is around 60,000 miles unless they’re faulty. Replacing the ignition coil packs and spark plugs is pretty simple if you have the proper tools. Please ensure the spark plugs are gapped properly or else there will be further engine damage. A mechanic or dealer would charge around $400-$500.

Buy Here: B7 A4 Replacement 2.0T Ignition Coil Packs
Buy Here: B7 A4 Replacement 2.0T Spark Plugs
Purchase Here: B7 A4 3.2L V6 Replacement Ignition Coils
Purchase Here: B7 A4 3.2L V6 Replacement Spark Plugs
DIY Difficulty:

2. Carbon Buildup in the Intake Valves

Carbon buildup is very common in all direct fuel injection vehicles on the road today, therefore it is hard to avoid. We will give tips on ways to prevent it below. So how does this happen? Well, fuel is sprayed directly into the combustion chamber through the valves and intake manifold. Most of the time, not all of the fuel passes through the valves or becomes soot/deposits. Over time these oil deposits or soot will clog the intake valves effectively making the engine harder to “breathe”. Believe it or not, this can severely dampen engine performance.

This is more common in vehicles that drive short trips a majority of the time. For example, a vehicle that is driven back and forth to work, 20-minute commute, every day of the week has a higher chance to develop carbon buildup than a vehicle that takes longer trips regularly. The reason this is is that the vehicle that takes longer trips regularly, has more time to burn off the excess deposits or gunk out of the intake valves.

Symptoms of Carbon Buildup:

  • Decreased fuel efficiency
  • Noticeable engine performance loss
  • Engine misfires – cold start
  • Engine knocking
  • Stalling engine

Ways to Prevent Carbon Buildup:

  • Running your engine above 3500 RPMs for an extended period of time (30+ minutes)
  • Using the highest quality fuel possible (Typically 93+ Octane)
  • Get the valves walnut blasted every 60,000 miles or when they need them done
  • Manually cleaning the valves

Preventative maintenance for carbon buildup is essential for a high-performance vehicle. If you know your way around the engine and can get to the intake valves, we would highly advise checking on them every 40,000 miles. If there is a lot of buildup, there are two options: manually clean them or get them professionally walnut blasted. Once the “pipes are clean” you will be able to tell the difference in the engine’s performance.

3. Excessive Oil Consumption

Unfortunately, excessive oil consumption is common in many Audi and Volkswagen engines, and it is no exception in most A4 model years. When this occurs, the engine consumes more oil than what is acceptably set by the OEM. This can get quite costly if it is ignored. If the low oil light is illuminating more than normal, we highly advise getting a compression test.

This problem was very popular in Gen 2 EA888 engines, which were produced in 2008. Essentially the piston rings were too thin out of the factory causing the engines to guzzle more oil than normal. Many customers have found this to be an issue around the 60,000-mile mark and spend on average $6,000.

Symptoms of Excessive Oil Consumption:

  • Oil deposits under the hood
  • Irregular oil pressure warning light
  • Decreased fuel economy
  • Blue smoke coming from the exhaust
  • Shaved metal in the oil pan

As we’ve stated above, if your vehicle is consuming more oil than normal, take it into the shop immediately, regardless of what engine you have. This can cause oil deposits if ignored, which will put more stress on an already stressed engine. If it is ignored, this can cause major engine damage causing a bill of up to $5,000.

4. PCV (Positive Crankcase Vent) Valve Failure

PCV valve failure is common on many Volkswagen and Audi engines. A PCV valve’s purpose is to capture vapors made from the engine and recirculate them through the intake system to be burned off before entering into the environment. Essentially, it’s a part to reduce emissions given off by the engine.

Believe it or not, a failing PCV valve can cause a lot of engine issues, as seen with the symptoms below. It is not only bad for your engine, but it is also bad for the environment because the valve is not controlling the vapors produced by the engine. The valve can fail in a few ways: normal wear and tear, faulty out of the factory, or getting stuck open or closed.

Symptoms of PCV Valve Failure:

  • Engine misfires
  • Rough engine performance
  • Rough idle
  • Whistling noise in the engine
  • Lean conditions (P0171 or P0507 fault codes)

PCV Valve Replacement Options:

Regardless of the failure, the PCV valve will have to be replaced. Luckily, it’s not an expensive part and it’s a rather straightforward DIY. If you aren’t too DIY savvy, a local mechanic or dealer will charge around $200 to replace the PCV valve.

Buy Here: B7 A4 Replacement PCV Valve
DIY Difficulty:

5. HPFP (High-Pressure Fuel Pump) Failure

A pretty common problem with B7 Audi A4’s is the cam follower and HPFP failing. Most of the time the cam follower will fail, which leads to the HPFP failing. A cam follower is a part that serves as a barrier between the camshaft and the HPFP to ensure they don’t rub together and cause serious engine damage. An HPFP is as it says, it is a pump that takes in fuel and compresses it for the direct injection system. If you plan to modify your engine, we highly advise upgrading the HPFP because the factory unit will not pump as much fuel that may be needed.

Symptoms of HPFP Failure:

  • Check Engine Light (CEL or MIL) illuminating
  • Fault codes P0087 or P0192
  • Slow acceleration
  • Metal clanking noise in the engine

HPFP Replacement Options:

A general rule of thumb would be to replace the cam follower during every oil change. You may think this is excessive, but the last thing you would want for your engine is to have the camshaft and HPFP rub together. The cam follower is a $35 part that will save you much more money in future engine damages. If there happens to be HPFP failure, we would advise replacing the intake camshaft as well. This is not an easy DIY and a mechanic would charge $500.

Buy Here: B7 A4 Replacement HPFP
DIY Difficulty:

6. Defective Fuel Injectors

Defective fuel injectors are most common on the 2.0TDI engine in the B7 Audi A4’s. The early 2.0TDI PD engines came with faulty injectors made by Siemens. However, there was a recall on these injectors, so since these vehicles are over a decade old, the majority of the defective injectors have been replaced by now. Fuel injectors do as it sounds, they inject fuel directly into the engine’s cylinder to initiate engine combustion. If there are defective fuel injectors, fuel will not be pushed through the cylinders at the factory engine’s levels. This will lead to decreased fuel efficiency if ignored for an extended period of time.

Symptoms of Fuel Injector Failure:

  • Engine misfires
  • Rough idle
  • Difficulty starting the engine
  • Decreased fuel efficiency
  • Gas dripping out of the engine

Fuel Injector Replacement Options:

Again, since there was a recall on these defective injectors, the majority of the B7 Audi A4’s on the market SHOULDN’T still have these in. However, if you are in the market for one, make sure to get maintenance records to see if this has been addressed. If you are a DIYer, this is a rather simple one to do on your own to save some money.

Buy Here: B7 A4 Individual Replacement Fuel Injector
Buy Here: B7 A4 Replacement Fuel Injector Kit
DIY Difficulty:

7. Premature Cam Lobe Wear

B7 Audi A4 Cam Lobe

Cam lobe wear is something that is common on the 2.0T engines. A cam lobe is a part on the camshaft that pushes against the valves to open them as the camshaft spins. What ends up happening in the 2.0t engines, is some of these lobes start to “round out”, meaning there wouldn’t be enough lift provided by the lobes to keep the valves open. This would lead to intake/exhaust restrictions in that specific cylinder.

Not only can this limit the engine’s performance but it can also cause major engine damage. Engine bucking, popping, or backfiring will start to occur. If left undiagnosed, this could be catastrophic. Cam lobe wear should not be as common as it is in the 2.0t engines. Usually, these can go the lifetime of a vehicle, but not with the 2.0t engine.

Symptoms of Cam Lobe Wear:

  • Lifter tapping
  • Missed cylinder
  • Engine backfires
  • Rough engine performance
  • Clicking noises coming from the engine

Cam Lobe Replacement Options:

We highly advise checking maintenance records if you are looking to buy a used B7 Audi A4 to see if the camshaft has been replaced with an OEM unit or an upgraded unit (best case). Typically when there is premature cam lobe wear, the camshaft will have to be replaced, which is not a cheap or easy task to DIY. A local mechanic or dealer will charge north of $850-$1,500 to perform a service like this, depending on what parts are purchased.

DIY Difficulty: Difficult

B7 Audi A4 Reliability

Just like many other cars, if vehicle maintenance is followed religiously, the B7 Audi A4 is very reliable. The things you will want to focus on with this vehicle are the cam follower, using high-quality oil, replacing the belts, filters, plugs, and coil packs on time. We’ve seen many of these vehicles last up to 200,000 miles.

If you want to check out more Audi content, here is our write-up on The Most Common Audi A4 B8 Problems.

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