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

The Diesel Particulate Filter (DPF) on the Mercedes R-Class W251 (models like R 350 CDI 4-Matic with OM642 engine) is an exhaust system component designed to trap soot particles from diesel exhaust gases. It helps reduce pollution by capturing harmful particulates and requires periodic regeneration to burn off accumulated soot.

Signs of a defective DPF include:

• Increased diesel fuel consumption
• Reduced engine power
• Check Engine Light activation with error codes such as P2463 (soot accumulation), P2002 (DPF efficiency below threshold), or limp mode activation
• Frequent or failed DPF regenerations and poor fuel economy

If you notice these symptoms, it is advised to get a diagnostic scan for accurate fault identification.

DPF regeneration is the process of burning off soot deposits to clear the filter and restore function.

• Passive/Active Regeneration: Driving continuously at 60-80 km/h for 25-30 minutes to reach combustion temperature (~600°C).
• Cleaning without removal: Using specialized diesel additives injected via the differential pressure sensor and forcing regeneration at 2000-2500 rpm.
• Diagnostic Tools: Use OBD scanners like YOUCANIC UCAN-II or VCDS to monitor soot load, differential pressure, and to manually initiate regeneration.

Limit ash accumulation to a maximum of 60 grams to ensure proper DPF function.

Replacement is recommended between 120,000 and 190,000 km or when excessive clogging occurs that regeneration cannot fix.

• Install a new DPF unit compatible with the R 350 CDI W251 model (length ~570 mm, catalytic converter integrated)
• Perform a mandatory Teach-in / Reset via OBD scanner to reset soot and ash counters in the vehicle ECU, preventing persistent error codes like P2463 or P2002 and enabling normal regeneration processes
• Check and replace all related gaskets, sensors, and injectors as per manufacturer instructions

It is critical to follow the official reset procedure after installation to ensure the DPF system operates correctly.

The DPF on the Mercedes R-Class W251 is integrated within the vehicle’s exhaust system, typically positioned downstream of the diesel oxidation catalyst and before the catalytic converter. The exact location allows it to effectively trap soot before gases exit the vehicle exhaust.

Proper sensor placement, including differential pressure sensors before and after the DPF, is essential for accurate monitoring and regeneration control.

Key maintenance points include:

• Avoid limiting vehicle use to short trips as the engine and exhaust do not reach optimal temperature for soot burn-off, harming DPF life
• Regularly check and replace engine oil and spark plugs following manufacturer service intervals
• Use diagnostic tools to monitor DPF soot loading and pressure difference to anticipate needed regeneration or cleaning
• After replacement, ensure full system checks and Teach-in procedures are completed

Following these recommendations helps maximize DPF lifespan and maintain vehicle performance.

The removal and replacement of the DPF can take several hours depending on workshop speed and tools available.

• DPF cleaning with additives plus regeneration usually requires about 30 minutes of controlled driving at highway speeds.
• Hardware replacement often requires 2 to 4 hours including disassembly, installation, and reset procedures with a scanner.

Additional time should be planned for if sensor replacements or exhaust gaskets need changing to ensure proper sealing and sensor function.

It is important to source your Diesel Particulate Filter from reputable manufacturers that provide new, certified products meeting European regulations and vehicle manufacturer specifications. Look for the following:

• Certified quality compliant with E24-103R or equivalent
• Manufactured using stainless steel INOX 409 with high-grade ceramic monoliths
• Availability of a 3-year warranty with coverage up to 100,000 km usage
• Clear documentation and support for proper installation and Teach-in reset
• Fast delivery options and good customer support

Choosing such a product ensures reliable performance, durability, and environmental compliance for your Mercedes R-Class diesel vehicle.

Always verify compatibility by VIN and follow official installation procedures including sensor and gasket replacements.