Citroen C5 Diesel Particulate Filter DPF

The Diesel Particulate Filter (DPF) on the Citroën C5 diesel models such as HDi 110 or 1.6 HDi is an anti-pollution ceramic device placed in the exhaust line after the catalytic converter. It traps and burns harmful soot particles emitted by the diesel engine to reduce pollution. It often uses a specific PSA/Citroën additive called EOLYS to lower the combustion temperature of soot to about 450°C, facilitating filter regeneration.

The DPF operates by:

• Trapping particles like carbon, hydrocarbons and sulfates emitted during low temperature phases (city driving or idling).
• Passive regeneration occurs automatically when driving at high temperature (e.g., highway), burning soot and storing ashes in the filter.
• If passive regeneration is insufficient, active regeneration is triggered by the engine control unit (ECU) injecting fuel into the exhaust to heat the filter via the catalytic converter.
• The EOLYS additive stored in a dedicated tank helps reduce regeneration temperature, improving efficiency on Citroën C5 HDi models.

Regular refilling of the additive tank is required to maintain optimal performance.

Common DPF issues on Citroën C5 1.6 HDi or HDi 110 include:

• DPF warning light illuminated on dashboard.
• Loss of engine power and hesitation during acceleration.
• Increased fuel consumption by up to 10%.
• Elevated harmful emissions.
• Abnormal differential pressure readings indicating filter or catalytic converter clogging.

These symptoms often result from frequent short trips or city driving, preventing proper regeneration, or from deposits like soot and oxidation buildup in the EGR, turbo, or catalytic converter.

DPF clogging mainly occurs due to:

• Frequent short journeys or city driving where the engine and exhaust don’t reach the temperature required for passive regeneration.
• Build-up of soot, calamine (carbon deposits), and oxidation residues.
• Contaminated or failing EGR valve, turbocharger, or catalytic converter.
• Insufficient refilling or malfunction of the EOLYS additive tank preventing effective soot combustion.

This can lead to engine asphyxiation and costly breakdowns if not addressed promptly.

Maintenance and cleaning options include:

• Forced regeneration by diagnostic procedure, running engine at about 3000 rpm to burn soot and reduce clogging.
• Manual cleaning by removing the DPF (four 13mm bolts, pressure sensor, catalytic converter clamp), using degreasers and vacuuming or blowing out dust (proper protective gear required).
• Hydrogen decarbonization treatments (Carbon Cleaning) to remove up to 75% of calamine deposits, restoring performance and reducing fuel consumption by about 10%.
• Regularly topping up the EOLYS additive to ensure effective regeneration.
• Following manufacturer guidelines for DPF servicing outlined in technical reviews.

Preventive measures include regular long-distance driving to ensure passive regeneration and use of quality fuel and oil.

DPF replacement is considered when regeneration and cleaning no longer restore performance, indicated by persistent clogging and warning messages. Replacement on Citroën C5 models is straightforward following the official technical repair manual instructions.

Approximate replacement costs can range from €500 to €1,600 for the DPF itself, with additional potential costs for related parts like turbochargers (€1,100–€2,500), EGR valves (€300–€400), or catalytic converters (€500–€1,600).

• Note: Always ensure correct part reference and quality for replacement filters.
• Proper fitment and installation by a qualified professional is critical to maintain performance and warranty.

A new DPF typically does not require regeneration before fitting as it starts clean. However, after installation, it is important to reset relevant sensors and the vehicle’s ECU so the system correctly monitors and manages regeneration cycles. Some garages perform an initial procedure to ensure the DPF is operating correctly within the vehicle's system.

Always follow the vehicle manufacturer’s or technical manual instructions for the correct installation and any post-fit procedures required.

EOLYS is a specific additive fluid stored in a dedicated tank designed for Citroën and PSA diesel vehicles equipped with DPFs. Its function is to reduce the combustion temperature of soot particles inside the filter to around 450°C compared to 550–600°C without it, thus improving the efficiency and frequency of regeneration.

• The additive tank requires periodic checking and refilling to maintain correct DPF performance.
• Failure to maintain adequate additive levels can lead to incomplete regeneration and clogging.
• Refilling the additive is a routine service operation recommended by Citroën and detailed in repair manuals and video tutorials.
• Using the correct additive ensures the longevity of your DPF and helps meet Euro emissions standards.

Always use approved fluids and follow service schedules for your Citroën C5 HDi model to avoid DPF and engine damage.