Subaru Subaru Legacy 2005-2009 Fuel System Specifications

The 2005-2009 Subaru Legacy is compatible with regular unleaded gasoline with an octane rating of 87 or higher. Using premium fuel (91 octane or higher) is not required but may improve performance in certain conditions. Avoid using diesel, E85, or any fuel with more than 10% ethanol, as it may damage the engine or fuel system components.

Regular maintenance for the fuel system includes inspecting and replacing the fuel filter every 30,000 miles, checking fuel lines for leaks or damage, and using fuel injector cleaner every 15,000 miles to prevent clogging. Additionally, ensure the fuel cap is tightly sealed to maintain proper pressure and avoid triggering the check engine light.

To replace the fuel filter, first, relieve fuel system pressure by removing the fuel pump fuse and running the engine until it stalls. Locate the fuel filter under the vehicle near the fuel tank. Disconnect the fuel lines using a line wrench, remove the mounting bracket, and install the new filter. Reconnect the lines, secure the bracket, and reinstall the fuel pump fuse. Start the engine and check for leaks.

Poor fuel economy can result from clogged fuel injectors, a dirty air filter, or incorrect tire pressure. Start by checking and replacing the air filter if necessary. Inspect tire pressure and adjust it to the recommended level. Use a fuel injector cleaner or have the injectors professionally cleaned. If issues persist, scan for error codes to identify potential sensor or engine problems.

To optimize fuel efficiency, maintain proper tire pressure, use high-quality fuel, and replace the air filter regularly. Avoid aggressive driving and excessive idling. Ensure the engine is tuned, and the fuel system is clean. Lightening the vehicle load and using cruise control on highways can also improve mileage. Regular maintenance, such as oil changes and spark plug replacements, further enhances performance.