📖 What It Does
Captures 99% of the soot a diesel engine emits. Without a DPF the air around diesel highways would still look like 1970s LA. With one, modern diesel exhaust is nearly invisible.
⚙ How It Works
Exhaust flows into one end of a honeycomb ceramic block with alternating plugged channels, forcing soot to deposit on the walls. As soot loads up, back-pressure rises. The ECU triggers an "active regen" by injecting extra fuel or post-combustion fuel to raise exhaust temperatures to 1100°F, which burns the soot to ash.
⚠ Symptoms When It Fails
Symptoms: DPF or "exhaust filter" warning light, reduced power, frequent regen cycles, increased fuel consumption, and eventually a forced regen or limp mode. Short trips and excessive idling are the top causes - the DPF never gets hot enough to self-clean. See full symptom guide.
💰 Replacement Cost
Cleaning or replacement: $300–$5,000. Professional cleaning is $300–$900. A new OEM DPF can be $3,000–$5,000+ on heavy-duty trucks.