Subaru Forester Diesel Particulate Filter DPF

The Diesel Particulate Filter (DPF) is an essential emission control device installed on modern Subaru Forester diesel vehicles. It traps fine soot particles from the exhaust gases to comply with Euro 4, Euro 5 and higher emission standards. This helps reduce the vehicle’s environmental impact and maintain engine performance.

The DPF operates in two main phases:

• Filtration : Captures soot and fine particulate matter during normal engine running.
• Regeneration : Burns off the accumulated soot to clean the filter. This can be passive (using exhaust heat) or active (injecting additional fuel or raising exhaust temperature to trigger combustion of soot).

Regeneration activates automatically when soot reaches a critical level, ensuring continued filter efficiency.

The DPF is mainly installed on Subaru Forester 2.0D diesel models from approximately 2013 to 2018 with the EE20 engine (147 hp), compliant with Euro 5 emission standards. It is also found in earlier versions under Euro 4 regulations such as SH and S12 series. Similar Subaru diesel models like the Outback are also equipped with DPFs.

Frequent issues include:

• Premature clogging : Often caused by frequent short, low-speed trips that prevent proper passive regeneration.
• Accumulation of incombustible ash : This cannot be burned off and causes irreversible blockages.
• Consequences : Failed or frequent regenerations, engine compression loss, higher fuel consumption, and costly component failures like turbo, EGR valve, or injectors.

Though Subaru diesel engines are reliable, their DPFs require proper driving and maintenance to avoid these issues.

DIY cleaning is not recommended due to the technical nature of DPF maintenance. Professional cleaning services use high-pressure reverse flow techniques or specific decarbonisation processes specialized for Subaru Forester 2.0D engines. These restore original performance and extend DPF lifespan effectively.

Consult specialist workshops or follow detailed guides from trusted sources if considering any hands-on steps.

Main options include:

• Professional cleaning : Economical and durable solution restoring original DPF function without replacing the part.
• Decarbonisation : A targeted cleaning approach removing soot and calamine build-up.
• Replacement : New original DPFs are available with a 3-year warranty, certified for Subaru Forester models. Replacement is costlier but a guaranteed fix for severely damaged filters.

Cleaning is generally preferred for cost-effectiveness and longevity, ensuring your vehicle meets emission standards efficiently.

The DPF warning light signals that the filter is reaching its soot capacity and regeneration is needed. Ignoring this can lead to clogging and damage.

• Try to complete a longer drive, preferably at higher speeds on a highway, to allow passive or forced regeneration.
• A diagnostic OBD tool can check soot levels and reset warning lights if regeneration is successful.
• If the light remains, professional intervention for cleaning or repair is recommended.

Regularly monitoring and maintaining the DPF is crucial to avoid costly repairs and maintain engine performance.

Choose high-performance DPFs with a 3-year warranty, manufactured in Europe with certified quality and compliance to regulations. Prefer original references compatible with Subaru Forester Euro 4/5 diesel engines, such as those with EE20 engines.

• Professional workshops specialising in Subaru diesel models offer expert cleaning and decarbonisation services.
• Online specialist suppliers provide direct-from-factory new DPF units certified by TÜV SÜD for reliability and durability.
• Check compatibility by engine code and model year to ensure optimum fit and performance.

Proper maintenance along with certified parts ensures environmental compliance, optimised fuel economy and vehicle longevity.

For tailored advice or support, consult technical experts qualified in Subaru diesel exhaust systems.