A Diesel Particulate Filter (DPF) is located in the exhaust system, typically in a section that also houses the catalytic converter (commonly referred to as the “cat”).
Many people believe the DPF is an emissions device, but technically, it is not. As the name suggests, it is a filter for particulates—solid particles formed when exhaust gases change into hard deposits of burnt oil and unburnt diesel. These particles accumulate on the face of the DPF, on the exhaust gas entry side (i.e. the engine exhaust manifold side).
As this build-up occurs, it restricts the flow of exhaust gases through the filter. This slows down the flow and increases pressure between the exhaust manifold and the DPF. A DPF pressure sensor sampling pipe, located between the manifold and the filter, allows this pressure to travel up to a sensor. If the pressure exceeds the vehicle’s ECU preset threshold, it triggers an engine management warning light and a DPF warning message.
Our Service: We visit your vehicle and chemically inject a specially formulated solution that breaks down and dissolves the soot and particulates. These are the substances sitting on the face of the DPF and causing the restriction. Once dissolved into liquid form, they flow through the filter and exit via the exhaust tip at the rear of the vehicle.
Important Warning: If you continue to drive after the DPF warning light has come on, the blockage can worsen significantly. This may render the filter uncleanable and class it as damaged.
The DPF system includes several sensors: two temperature sensors, a back-pressure sensor, and—on newer vehicles—a soot mass level sensor. If any of these fail, the filter can become blocked and the vehicle may enter limp mode.
Our Advice:
- If the DPF or engine management light comes on, get a full professional DPF system diagnostic as soon as possible.
- Do not continue driving with the warning light on, as this can worsen the fault and cause further damage.
- Be aware: Most manufacturers recommend a DPF lifespan of around 130,000 miles or 12 years, whichever comes first. This assumes the vehicle is regularly driven on motorway journeys of at least 30 minutes at speeds over 55 mph.
- Chemical cleaning with professional-grade fluid is an excellent way to restore the filter. However, it is not a magic wand—if the filter is cracked or damaged due to overheating, the clean may not be fully successful or may fail entirely.
- Act quickly: As soon as any fault appears, have the system checked by a qualified professional with the correct equipment and experience.
