The Subaru Impreza is a popular compact car known for its reliability, practicality, and standard all-wheel-drive. For a period, Subaru offered a diesel engine option in the Impreza, specifically a 2.0-liter diesel. This engine, while not as common as its gasoline counterparts, provided a unique blend of fuel efficiency and Subaru's signature ruggedness. This article dives deep into the Subaru Impreza 2.0 diesel engine, covering its specifications, common issues, maintenance, and overall reliability.

Understanding the Subaru Impreza 2.0 Diesel Engine

The Subaru Impreza 2.0 diesel engine, often referred to as the EE20 engine, was a horizontally-opposed (boxer) four-cylinder diesel. This configuration is a hallmark of Subaru engines, known for its smooth operation and low center of gravity, which contributes to the car's handling. The 2.0-liter diesel engine was designed to offer a more fuel-efficient alternative to the gasoline engines, while still providing adequate power for everyday driving. It featured a common rail direct injection system, a variable geometry turbocharger, and a diesel particulate filter (DPF) to meet emissions standards. The engine typically produced around 148 horsepower and 258 lb-ft of torque, providing a good balance of performance and economy. It was primarily available in European markets, where diesel vehicles were more popular.

Key features of the Subaru Impreza 2.0 diesel engine included:

• Horizontally-Opposed Configuration: This design helps to reduce vibrations and provides a lower center of gravity, improving handling.
• Common Rail Direct Injection: This system ensures precise fuel delivery, improving efficiency and reducing emissions.
• Variable Geometry Turbocharger: This turbocharger optimizes performance across the rev range, providing good low-end torque and responsive acceleration.
• Diesel Particulate Filter (DPF): This filter traps and burns soot particles, reducing emissions and meeting environmental regulations.

Common Issues and Problems

Like any engine, the Subaru Impreza 2.0 diesel is prone to certain issues. Understanding these common problems can help you maintain your vehicle better and address issues before they lead to major repairs. Here's a detailed look at some of the typical problems encountered with this engine:

Diesel Particulate Filter (DPF) Problems

The Diesel Particulate Filter (DPF) is designed to trap soot and reduce emissions. However, it can become clogged over time, especially if the car is primarily used for short trips where the engine doesn't get hot enough to regenerate the filter. Signs of a clogged DPF include reduced engine performance, increased fuel consumption, and a warning light on the dashboard. In severe cases, a clogged DPF can cause the engine to enter limp mode, restricting power to prevent damage. Regular maintenance, including occasional long drives at highway speeds, can help to keep the DPF clean. In some cases, a forced regeneration or professional cleaning may be necessary.

Injector Problems

The fuel injectors in the 2.0 diesel engine are precision components that deliver fuel into the cylinders. Over time, these injectors can become clogged or fail, leading to poor engine performance, rough idling, and increased emissions. Symptoms of injector problems include difficulty starting the engine, misfires, and a noticeable loss of power. Regular fuel system cleaners and high-quality diesel fuel can help to prevent injector problems. If an injector fails, it will need to be replaced, which can be a relatively expensive repair.

Turbocharger Issues

The turbocharger is crucial for boosting the engine's power output. The variable geometry turbocharger (VGT) in the 2.0 diesel engine is designed to optimize performance at different engine speeds. However, the turbocharger can be prone to issues such as leaks, bearing failure, and problems with the variable geometry mechanism. Signs of a failing turbocharger include a whistling noise, reduced power, and excessive smoke from the exhaust. Regular oil changes with high-quality synthetic oil can help to prolong the life of the turbocharger. If the turbocharger fails, it will need to be repaired or replaced.

EGR Valve Problems

The Exhaust Gas Recirculation (EGR) valve is used to reduce emissions by recirculating exhaust gases back into the intake manifold. Over time, the EGR valve can become clogged with carbon deposits, leading to poor engine performance, rough idling, and increased emissions. Symptoms of EGR valve problems include a rough idle, hesitation during acceleration, and a check engine light. Regular cleaning of the EGR valve can help to prevent problems. In some cases, the EGR valve may need to be replaced.

Dual Mass Flywheel (DMF) Failure

The dual mass flywheel (DMF) is designed to reduce vibrations and improve driving comfort. However, the DMF can wear out over time, leading to increased vibrations, noise, and difficulty shifting gears. Symptoms of DMF failure include a rattling noise when idling, vibrations when accelerating, and difficulty engaging gears. If the DMF fails, it will need to be replaced, which can be a relatively expensive repair.

Maintenance Tips for the Subaru Impreza 2.0 Diesel

Proper maintenance is essential for keeping your Subaru Impreza 2.0 diesel running smoothly and preventing costly repairs. Here are some key maintenance tips:

Regular Oil Changes

Regular oil changes are crucial for maintaining the health of your engine. Use high-quality synthetic oil that meets the specifications for your engine. Change the oil and filter at the recommended intervals, typically every 7,500 to 10,000 miles, or as specified in your owner's manual. Regular oil changes help to lubricate the engine, remove contaminants, and prevent wear.

Check and Replace Filters

Regularly inspect and replace the air filter, fuel filter, and cabin filter. A clean air filter ensures that the engine receives adequate air, improving performance and fuel efficiency. A clean fuel filter prevents contaminants from entering the fuel system, protecting the injectors and fuel pump. A clean cabin filter ensures that the air inside the car is clean and fresh.

Inspect and Clean the EGR Valve

The EGR valve can become clogged with carbon deposits over time, leading to poor engine performance. Regularly inspect and clean the EGR valve to prevent problems. You can use a carburetor cleaner or a specialized EGR valve cleaner to remove carbon deposits.

Monitor the DPF

The Diesel Particulate Filter (DPF) requires regular maintenance to prevent clogging. Ensure that you take your car for occasional long drives at highway speeds to allow the DPF to regenerate. If the DPF becomes clogged, you may need to have it professionally cleaned or replaced.

Check and Maintain the Cooling System

The cooling system is essential for preventing the engine from overheating. Regularly check the coolant level and inspect the hoses and radiator for leaks. Flush and replace the coolant at the recommended intervals, typically every two to three years.

Inspect and Maintain the Fuel System

Use high-quality diesel fuel and consider using a fuel system cleaner periodically to help keep the fuel injectors clean. Regularly inspect the fuel lines and fuel pump for leaks or damage.

Reliability of the Subaru Impreza 2.0 Diesel Engine

The Subaru Impreza 2.0 diesel engine can be reliable if properly maintained. However, it's important to be aware of the common issues and take steps to prevent them. Regular maintenance, high-quality fluids, and addressing problems promptly can help to extend the life of the engine. Overall, the reliability of the Subaru Impreza 2.0 diesel engine is comparable to other modern diesel engines, but it requires diligent maintenance to ensure optimal performance.

Is the Subaru Impreza 2.0 Diesel a Good Choice?

Whether the Subaru Impreza 2.0 diesel is a good choice depends on your individual needs and preferences. If you prioritize fuel efficiency and enjoy the added torque of a diesel engine, the Impreza 2.0 diesel can be a good option. However, it's important to be aware of the potential maintenance requirements and common issues. If you're considering purchasing a used Impreza 2.0 diesel, be sure to have it thoroughly inspected by a qualified mechanic to identify any potential problems. Also, consider that diesel models are less common, which might affect parts availability and servicing expertise in some regions.

Conclusion

The Subaru Impreza 2.0 diesel engine offers a unique blend of fuel efficiency and Subaru's renowned all-wheel-drive capability. While it has its share of common issues, proper maintenance and timely repairs can ensure its reliability and longevity. By understanding the engine's characteristics and following the recommended maintenance schedule, you can enjoy the benefits of this efficient and capable engine for years to come.