A DPF system is the part of a modern diesel engine's aftertreatment that traps and burns off the soot (particulate matter) produced during combustion. At the centre of the DPF system is the diesel particulate filter itself — a ceramic monolith that captures soot before it reaches the atmosphere.
What a diesel particulate filter does
A diesel particulate filter physically traps soot from the exhaust stream. Over time the filter fills up, and it must be regenerated — soot is burned off inside the filter and converted to ash and CO₂. This is where "DPF regeneration" (or "DPF regen") comes in.
DPF system components
- DPF filter — the ceramic filter body that traps soot.
- DOC (Diesel Oxidation Catalyst) — upstream of the DPF, aids passive regen.
- EGT sensors — monitor exhaust gas temperature around the DPF.
- Differential pressure sensor — measures how full the DPF is.
- PM sensor — validates DPF condition on many modern platforms.
- ECU — commands active regen when soot load is high enough.
Common signs of DPF failure
- DPF warning light on the dashboard
- Frequent forced regenerations required
- Reduced power / limp mode
- Increased fuel consumption
- Fault codes referencing soot load, backpressure or DPF efficiency
DPF and SCR — how they relate
On Euro VI and comparable diesel platforms, the DPF works alongside the SCR system — the DPF handles particulate matter, while SCR handles NOx via DEF/AdBlue and the SCR catalyst.