Peugeot 407 Diesel Particulate Filter DPF

The DPF on the Peugeot 407 HDI is a component of the exhaust system designed to capture harmful soot particles from diesel exhaust gases. It stores these particles and periodically burns them off during a process called regeneration, reducing pollution and protecting the environment.

The system's principle is based on exhaust gases passing through a porous filter trapping solid particles. Key components include:

• Eolys additive (cerine): Stored in a 3L tank lasting ~120,000 miles; injected into fuel to lower particle combustion temperature from ~600°C to ~450°C for safer regeneration.
• Pressure sensors: Two sensors measure pressure difference across the DPF to detect soot load; high pressure triggers limp mode (power limited to 2200 rpm).
• Engine control unit (ECU): Manages post-combustion fuel injection to heat exhaust gases facilitating regeneration.
• Other systems: Electrical heating and air intake warming help accelerate the regeneration process.

Regeneration removes accumulated soot from the DPF by burning it at high temperatures. There are two main types:

• Natural regeneration: Happens automatically during long drives at sustained speeds (every 350-800 miles) when exhaust temperature reaches ~450°C.
• Assisted or forced regeneration: Triggered if short urban trips prevent sufficient temperature rise. The ECU injects extra fuel post-combustion and activates fans and heaters to raise temperature, regenerating the filter either while driving or via garage diagnostic tools at higher engine rpm.

The system monitors soot loading via pressure sensors categorized into zones A (normal), B (medium – assisted regeneration), and C (high – urgent forced regeneration) to maintain DPF efficiency.

Frequent issues include:

• DPF clogging, especially after many short urban trips—signs are DPF warning light, limp mode activation, power loss, and black smoke.
• Low additive level warning—failure to refill can lead to rapid soot buildup and blockages.
• Potential engine damage due to excessive back pressure if clogging is not addressed.

Proper diagnostics with Peugeot tools like Diagbox and timely maintenance can avoid about 90% of these faults.

Maintenance tips and solutions include:

• Refilling Eolys additive: Access the 3L reservoir under the hood and refill every ~120,000 miles (~50-100€ cost).
• Forced regeneration procedure: Use an OBD diagnostic tool (e.g., PP2000/Diagbox) with the engine warm, ramp up to 4000 rpm, maintain for 10-30 minutes, then reset codes and additive level.
• Cleaning: DPF can be removed and cleaned manually with hot water and additives or professionally cleaned (~200-500€).
• Replacement: New original DPFs cost between €800-1500 including labor; illegal removal is strongly discouraged and not recommended.
• Preventive care: Regular highway driving to reach operating temperature, quality additives, and avoiding short trips dramatically extend DPF life.

Yes, the DPF can become blocked if regeneration does not properly occur, particularly due to short trips with insufficient exhaust temperature. The pressure sensors before and after the filter monitor soot load by measuring differential pressure. If pressure is too high, the ECU signals clogging through warning messages and may limit engine power. Proper sensor function is critical to detect when soot accumulation reaches critical levels.

While some consider removing the DPF to avoid clogging and maintenance costs, it is not a recommended or legal solution. The DPF plays an essential role in reducing particulate emissions and pollution. Removal can cause fines, fail emissions tests, damage other engine components, and void warranties. Proper maintenance and regeneration are the recommended ways to ensure good performance and longevity of the Peugeot 407 HDI engine and exhaust system.

The Eolys DPF additive is usually available through authorized automotive parts stores or Peugeot dealerships. Prices typically range between €50 and €100 for a refill that lasts approximately 120,000 miles. When purchasing, ensure the additive is the original high-quality product to guarantee proper operation and to preserve engine power and DPF efficiency.

For best results, use genuine additives and follow the Peugeot service intervals for refilling and maintenance.