Volkswagen Multivan Diesel Particulate Filter DPF T4 (1990-2003)

The DPF is a ceramic filter fitted in the exhaust system of the Volkswagen Multivan T4 equipped with a 2.5 TDI diesel engine (codes AJT). It traps harmful soot particles from exhaust gases to reduce emissions and complies with Euro 3/4 standards. The filter regenerates automatically by burning off the soot during driving conditions.

Common signs of a clogged or defective DPF on your Volkswagen T4 include:

• Increased fuel consumption
• Loss of engine power
• Illumination of the Check Engine light
• Abnormal differential pressure readings across the DPF sensor

High pressure differences, especially above 160-300 mbar, indicate saturation, preventing regeneration and requiring cleaning or replacement.

DPF cleaning includes passive and forced regeneration methods:

• Passive regeneration: Driving at 60-80 km/h for 25-30 minutes raises the exhaust temperature to burn off soot.
• Forced regeneration: Conducted via diagnostic tools (like VCDS), monitoring DPF differential pressure sensors to trigger soot combustion.
• Chemical cleaning sprays designed specifically for DPFs can be used to assist in cleaning soot and ash deposits.

Regular checks of wiring, hoses, and sensors are essential for diagnostics and maintaining DPF condition.

The DPF for the Volkswagen Multivan T4 2.5 TDI typically requires replacement around every 120,000 km to avoid clogging problems commonly encountered between 125,000 and 165,000 km. It can store up to 60 grams of ash before irreversible blockage occurs. Proper driving conditions and avoiding excessive short trips help prolong its life.

A range of high-quality chemical cleaners in aerosol form are available to maintain your DPF, including products formulated without silicone for catalytic converters. Additionally, full replacement DPF units built with certified ceramic materials and stainless steel housings offer durable and environmentally compliant options.

• Chemical cleaners: Aerosol sprays suitable for catalytic and particulate filters
• Complete DPF units: Manufactured with premium ceramics and INOX 409 stainless steel, certified for Euro 3/4 standards

For best results, consult a qualified mechanic for fitting and diagnostics, especially concerning sensor checks and system integrity.

If you notice increased fuel consumption, engine power loss, or the Check Engine light is on, these may be warning signs your DPF is clogged. Measuring the pressure differential across the DPF sensor can confirm this:

• At idle (engine warm, 80°C), normal pressure differential is 0-10 mbar.
• At 2500-3000 rpm, pressure should remain below 90 mbar; higher values indicate soot or ash saturation.
• Pressure >160-300 mbar means regeneration is no longer possible and cleaning or replacement is required.

Regular diagnostic checks and using quality DPF cleaners can help prevent clogging issues.

Removing the DPF from your vehicle is not recommended and may be illegal in many regions due to emission regulations. The DPF is part of the vehicle's emission control system designed to reduce harmful diesel particulates. Avoiding removal helps keep emissions within legal limits and protects air quality.

• Removal may cause warning lights and engine faults
• It can lead to higher emissions, fines, or failed vehicle inspections
• Replacement with an appropriate DPF is the preferred option when clogged or damaged

Consult with your garage or emission specialist for compliant solutions.

Proper driving habits and maintenance can extend the life of your DPF and ensure effective regeneration:

• Avoid excessive short journeys that prevent the engine reaching optimal temperature
• Drive regularly at speeds of 60-80 km/h for 25-30 minutes to enable passive regeneration
• Use recommended DPF cleaning products as part of regular maintenance
• Monitor engine and sensor diagnostics to detect early signs of clogging
• Follow dealer or garage advice for scheduled servicing and possible forced regeneration

Maintaining your Volkswagen Multivan T4's DPF according to these guidelines helps reduce fuel consumption, prevents light warnings, and keeps exhaust emissions clean.