Mercedes R-Class Diesel Particulate Filter DPF W251 (2005-2017)

The Diesel Particulate Filter (DPF) is installed on diesel versions of the Mercedes R-Class W251/V251 produced between 2005 and 2017. Models mainly include those with CDI engines such as the R 350 CDI 4-MATIC and R 320 CDI 4-MATIC. Other variants like the R 400 3.0 4-MATIC petrol and R 500 exist but the focus is on diesel engines equipped with DPFs.

The key compatible diesel engines include:

• OM 642.872 Diesel 3.0L (265 HP / 195 kW) used in R 350 CDI 4-MATIC (251.023 / 251.123)
• 3.0L Diesel, 214 HP (157 kW) variant of R 350 CDI 4-MATIC
• 3.0L Diesel 211 HP (155 kW) in R 320 CDI 4-MATIC (W251/125)

DPF units listed correspond to both standard new parts and occasional generic references for W251 models.

The diesel particulate filter captures and filters soot and fine particles from exhaust gases. It supports automatic or forced regeneration cycles to burn off accumulated soot, typically managed via onboard diagnostics (OBD) systems. This reduces harmful emissions and ensures compliance with Euro 4/5 emission regulations.

• Particulate filtration to limit engine pollution
• Automatic regeneration to maintain filter efficiency
• Diagnostic monitoring via DPF sensors

This function is crucial to keep the vehicle emission-compliant and avoid failures during technical inspections.

Common issues pointing to a clogged or faulty DPF include:

• DPF warning light illuminated on dashboard
• Noticeable loss of engine power or reduced vehicle performance
• Frequent limp mode activation to protect the engine
• Increased fuel consumption or unusual exhaust pressure

If these symptoms occur, the DPF needs diagnostic checking and may require cleaning or replacement.

DPF replacement is necessary when cleaning fails to restore proper function or the filter is physically damaged. Replacement parts can be original equipment manufacturer (OEM) or high-quality aftermarket units compatible with the engine code (e.g., OM642.872).

• Ensure correct DPF part referencing per engine and model year
• DPF replacement should be performed by a professional using appropriate tools and diagnostic equipment
• Old DPF removal involves detachment from the exhaust system rear section
• Use new gaskets and check sensor connections during installation

Typical replacement times vary but planning for at least a couple of hours is recommended. Consult repair manuals for exact procedure details.

DPF cleaning can be achieved by forced regeneration using diagnostic tool commands or removal for specialised cleaning treatments. It is important to:

• Use a certified OBD tool to trigger regeneration cycles
• Monitor pressure and temperature sensors to identify clogging
• Avoid prolonged city driving which leads to soot build-up
• Consider fuel additives designed to aid soot burn-off

Manual cleaning requires removal and sending the DPF to a specialist cleaner or using ultrasonic equipment to remove particulate buildup without damaging the ceramic monolith.

The DPF is positioned within the exhaust system, typically at the rear section close to the catalytic converter. It integrates with the catalytic converter to form a combined unit for efficient particle filtration and emission control.

• Located downstream of the engine’s exhaust manifold
• Connected via flanges and gaskets to the rear exhaust pipe
• Equipped with sensors that monitor soot load and pressure differentials

Accessing the DPF requires safely lifting the vehicle and removing protective panels or heat shields.

High-quality DPF replacements for Mercedes R-Class W251 models can be obtained directly from specialised manufacturers offering:

• Brand new, high-performance DPF units certified to OEM standards
• Manufactured using stainless steel INOX 409 with advanced ceramic monoliths
• 3-year warranty covering up to 100,000 km usage
• Factory direct pricing with fast delivery options

It is advised to verify part compatibility using your vehicle VIN and engine code. Avoid using uncertified or reconditioned parts to maintain vehicle performance and comply with emission regulations.

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