The Subaru Forester 2.0 diesel turbo is a popular choice for those seeking a reliable and capable SUV. However, like any turbocharged engine, it's not immune to potential issues. In this article, we'll dive deep into the world of the Subaru Forester 2.0 diesel turbo, covering common problems, replacement options, and everything you need to know to keep your Forester running smoothly.

Understanding the Subaru Forester 2.0 Diesel Turbo

Before we jump into the nitty-gritty, let's get a good grasp of what we're dealing with. The Subaru Forester 2.0 diesel engine, often referred to as the EE20 engine, is a horizontally opposed, four-cylinder engine. This design, also known as a "boxer" engine, is a signature feature of Subaru vehicles, known for its smooth operation and low center of gravity, which contributes to improved handling. The turbocharger bolted onto this engine significantly boosts its power and torque, making it a capable performer both on and off the road.

This engine made its debut in the Forester lineup in 2008 and has been a popular choice for drivers looking for a blend of fuel efficiency and performance. The turbocharger works by forcing more air into the engine's cylinders, allowing it to burn more fuel and produce more power. This is especially beneficial when towing, climbing hills, or simply needing extra oomph for merging onto the highway. However, the added complexity of a turbocharger also means there are more components that can potentially fail, which brings us to the common issues.

The turbocharger itself is a complex piece of machinery, consisting of a turbine wheel and a compressor wheel connected by a shaft. Exhaust gases from the engine spin the turbine wheel, which in turn spins the compressor wheel. The compressor wheel then draws in fresh air, compresses it, and forces it into the engine's intake manifold. This increased air pressure allows the engine to burn more fuel, resulting in a significant boost in power. The system also includes various sensors, valves, and hoses that regulate the turbocharger's operation and ensure it's working efficiently.

Common Problems with the Subaru Forester 2.0 Diesel Turbo

Okay, let's talk about the elephant in the room: what can go wrong with your Subaru Forester 2.0 diesel turbo? Here are some of the most common issues reported by owners:

1. Turbocharger Failure

This is arguably the most significant concern. Turbocharger failure can manifest in several ways, including:

• Loss of Power: You might notice a significant decrease in acceleration and overall engine performance. The car will feel sluggish and unresponsive, especially when trying to accelerate quickly.
• Excessive Smoke: Blue or white smoke from the exhaust could indicate oil leaking into the turbocharger. This is a serious issue and should be addressed immediately.
• Whining or Screeching Noises: Unusual noises coming from the turbocharger area can be a sign of worn bearings or other internal damage. These noises often increase with engine RPM.
• Check Engine Light: The dreaded check engine light might illuminate, indicating a problem with the turbocharger system. A diagnostic scan will be needed to confirm the issue.

Several factors can contribute to turbocharger failure. Oil starvation is a major culprit. Turbochargers operate at extremely high speeds (over 100,000 RPM), and they rely on a constant supply of clean oil for lubrication and cooling. If the oil supply is inadequate or the oil is contaminated, the turbocharger's bearings can wear out prematurely, leading to failure. Regular oil changes with the correct type of oil are crucial for preventing this issue. Foreign object damage is another potential cause. If debris enters the turbocharger, it can damage the turbine or compressor wheels, leading to imbalance and failure. This can happen if the air filter is not properly maintained or if there's a problem with the intake system. Overheating can also damage the turbocharger. Excessive heat can cause the turbocharger's components to warp or crack, leading to failure. This can happen if the engine is worked too hard for extended periods or if there's a problem with the cooling system. Finally, general wear and tear can simply cause the turbocharger to fail over time. Like any mechanical component, the turbocharger has a limited lifespan, and it will eventually need to be replaced.

2. Diesel Particulate Filter (DPF) Issues

The DPF is designed to trap soot and other particulate matter from the exhaust. However, it can become clogged over time, leading to:

• Reduced Engine Performance: A clogged DPF can restrict exhaust flow, leading to a decrease in power and fuel efficiency.
• DPF Warning Light: The DPF warning light on the dashboard will illuminate, indicating that the filter needs to be regenerated.
• Forced Regeneration: The engine might enter a forced regeneration mode, where it injects extra fuel to burn off the soot in the DPF. This can lead to increased fuel consumption and a hot exhaust smell.
• DPF Failure: If the DPF is not properly maintained, it can become permanently clogged and require replacement.

The DPF needs to regenerate periodically to burn off the accumulated soot. This usually happens automatically while driving at highway speeds. However, if you mostly drive short distances at low speeds, the DPF may not get hot enough to regenerate properly, leading to clogging. You can try to force a regeneration by driving on the highway for an extended period, but if the DPF is severely clogged, it may need to be professionally cleaned or replaced. Using the correct type of engine oil is also crucial for preventing DPF problems. Low-quality oil can produce more soot, which can clog the DPF more quickly. Regular servicing and maintenance can help to prevent DPF issues. This includes checking the DPF's condition, monitoring its pressure differential, and performing forced regenerations when necessary.

3. EGR Valve Problems

The Exhaust Gas Recirculation (EGR) valve recirculates a portion of the exhaust gas back into the engine's intake manifold. This helps to reduce emissions by lowering combustion temperatures. However, the EGR valve can become clogged with carbon deposits over time, leading to:

• Rough Idling: The engine might idle roughly or stall.
• Poor Acceleration: The engine might hesitate or stumble during acceleration.
• Increased Emissions: The engine might produce more smoke and pollutants.
• Check Engine Light: The check engine light might illuminate, indicating a problem with the EGR system.

The EGR valve is exposed to hot exhaust gases and carbon deposits, which can cause it to become clogged and malfunction. Regular cleaning or replacement of the EGR valve can help to prevent these problems. Using high-quality fuel and performing regular engine maintenance can also help to reduce carbon buildup in the EGR system. If you notice any of the symptoms mentioned above, it's important to have the EGR valve checked by a qualified mechanic. Ignoring these problems can lead to further engine damage and increased emissions.

4. Injector Issues

Fuel injectors are responsible for delivering fuel into the engine's cylinders. Over time, they can become clogged or worn, leading to:

• Poor Fuel Economy: You might notice a decrease in your car's fuel efficiency.
• Misfiring: The engine might misfire, causing it to run roughly.
• Increased Emissions: The engine might produce more smoke and pollutants.
• Difficulty Starting: The engine might be difficult to start, especially in cold weather.

Fuel injectors are precision components that can be sensitive to fuel quality and contamination. Using high-quality fuel and adding fuel injector cleaner to your fuel tank periodically can help to keep the injectors clean and functioning properly. If you notice any of the symptoms mentioned above, it's important to have the fuel injectors checked by a qualified mechanic. They can test the injectors to see if they are delivering the correct amount of fuel and clean or replace them if necessary. Regular fuel filter replacement is also important for preventing injector problems. A dirty fuel filter can allow contaminants to reach the injectors, causing them to become clogged or damaged.

5. Sensor Malfunctions

Modern engines rely on a variety of sensors to monitor their performance and adjust their operation accordingly. If a sensor malfunctions, it can lead to a variety of problems, including:

• Reduced Engine Performance: The engine might not run as smoothly or efficiently.
• Increased Emissions: The engine might produce more smoke and pollutants.
• Check Engine Light: The check engine light might illuminate, indicating a problem with the sensor system.

Some common sensor problems in the Subaru Forester 2.0 diesel include issues with the mass airflow (MAF) sensor, oxygen (O2) sensors, and crankshaft position sensor. A faulty MAF sensor can cause the engine to run lean or rich, leading to poor performance and increased emissions. Faulty O2 sensors can also affect fuel economy and emissions. A faulty crankshaft position sensor can cause the engine to misfire or stall. Regular maintenance and diagnostic scans can help to identify and address sensor problems before they cause major issues. When replacing sensors, it's important to use high-quality parts from a reputable supplier. Cheap aftermarket sensors may not be accurate or reliable, which can lead to further engine problems.

Replacing the Turbo on a Subaru Forester 2.0 Diesel

If your Subaru Forester 2.0 diesel turbo has failed, you'll need to replace it. This is a significant job, and it's generally recommended to have it done by a qualified mechanic. However, if you're a confident DIYer with the necessary tools and experience, you can tackle it yourself. Here's a general overview of the process:

1. Disconnect the Battery: Always disconnect the battery before working on any electrical components.
2. Remove the Old Turbo: This involves disconnecting various hoses, pipes, and sensors, and then unbolting the turbocharger from the exhaust manifold. Be sure to label all the connections to make reassembly easier.
3. Inspect the Oil Lines: Check the oil feed and drain lines for any blockages or damage. Replace them if necessary.
4. Install the New Turbo: Carefully install the new turbocharger, ensuring all the gaskets and seals are in good condition. Tighten the bolts to the correct torque specifications.
5. Reconnect Everything: Reconnect all the hoses, pipes, and sensors, referring to your labels to ensure everything is in the correct place.
6. Prime the Turbo: Before starting the engine, prime the turbocharger by cranking the engine for a few seconds without starting it. This will allow oil to circulate through the turbocharger and lubricate the bearings.
7. Start the Engine: Start the engine and let it idle for a few minutes. Check for any leaks or unusual noises.
8. Test Drive: Take the car for a test drive to ensure the new turbocharger is working properly.

Important Considerations:

• Turbocharger Quality: When replacing the turbo, don't skimp on quality. Opt for a reputable brand to ensure reliable performance and longevity.
• Cleanliness: Keep everything clean during the replacement process to prevent dirt or debris from entering the turbocharger.
• Proper Tools: Use the correct tools for the job to avoid damaging any components.
• Torque Specifications: Tighten all bolts to the correct torque specifications to ensure a secure and leak-free connection.

Tips for Maintaining Your Subaru Forester 2.0 Diesel Turbo

Prevention is always better than cure! Here are some tips to help you keep your Subaru Forester 2.0 diesel turbo running smoothly and avoid costly repairs:

• Regular Oil Changes: Change the engine oil and filter regularly, using the correct type of oil recommended by Subaru. This is arguably the most important thing you can do to protect your turbocharger.
• Use High-Quality Fuel: Use high-quality diesel fuel from a reputable source. Avoid using fuel from unknown or unreliable sources, as it may contain contaminants that can damage the fuel system and turbocharger.
• Maintain the Air Filter: Replace the air filter regularly to prevent dirt and debris from entering the turbocharger.
• Avoid Short Trips: If possible, avoid making frequent short trips, as this can prevent the DPF from regenerating properly. Try to take the car for a longer drive on the highway occasionally to allow the DPF to burn off accumulated soot.
• Let the Engine Warm Up: Allow the engine to warm up for a few minutes before driving hard, especially in cold weather. This will allow the oil to circulate properly and lubricate the turbocharger bearings.
• Let the Engine Cool Down: After a long drive or heavy use, let the engine idle for a few minutes before turning it off. This will allow the turbocharger to cool down and prevent oil from coking in the bearings.
• Regular Servicing: Have your car serviced regularly by a qualified mechanic. They can check the condition of the turbocharger, DPF, EGR valve, and other components and identify any potential problems before they become serious.

Conclusion

The Subaru Forester 2.0 diesel turbo can be a reliable and enjoyable vehicle, but it's essential to be aware of the potential issues and take steps to maintain it properly. By following the tips outlined in this article, you can help to ensure that your Forester runs smoothly for many years to come. Remember, regular maintenance, high-quality parts, and a little bit of preventative care can go a long way in keeping your turbocharger and engine in top condition.