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Diesel Particulate Filter (DPF)
 

Diesel Particulate Filter

A Diesel Particulate Filter (DPF) is a critical component in modern diesel engine exhaust systems, designed to reduce harmful emissions. Its primary function is to capture and store soot (particulate matter) produced by the combustion process in diesel engines, preventing it from being released into the atmosphere.​

The DPF is typically made from ceramic materials like cordierite or silicon carbide, and has a honeycomb-like structure with alternating plugged channels. This structure forces the exhaust gases to flow through the porous walls of the filter, trapping soot particles in the process.​

Over time, the collected soot builds up and the filter needs to be cleaned. This is done through a process called regeneration, where high exhaust temperatures burn off the accumulated soot, turning it into harmless carbon dioxide. Regeneration can happen in different ways:

  • Passive regeneration – occurs automatically during normal driving when the exhaust is hot enough.

  • Active regeneration – triggered by the engine control unit (ECU), often by injecting extra fuel to raise the exhaust temperature.

If a DPF becomes too clogged and regeneration fails, it can cause reduced engine performance, increased fuel consumption, and potential engine damage. Regular maintenance and driving habits that support regeneration (like occasional highway driving) are essential to keep the DPF functioning properly.




Exhaust Gas Recirculation (EGR)
 

Exhaust Gas Recirculation (EGR) is an emissions control system used in petrol and diesel engines to reduce nitrogen oxide (NOx) emissions. It works by recirculating a portion of an engine's exhaust gases back into the intake air.

Common Problems with EGR Systems:

  • Clogging or carbon buildup – Can cause poor engine performance, increased emissions, or rough idling.

  • Cracked EGR Cooler – Can lead to coolant leakage. 

  • Stuck EGR valve – May lead to a check engine light or increased fuel consumption.

  • Sensor or wiring issues – Can result in improper EGR operation or system failure.

Exhaust Gas Recirculation




Selective Catalytic Reduction (SCR)
 

Selective Catalytic Reduction

Selective Catalytic Reduction (SCR) is an advanced active emissions control technology used in diesel engines to reduce nitrogen oxides (NOâ‚“) emissions, which are harmful pollutants contributing to smog and acid rain.

SCR involves injecting a liquid-reductant agent, typically Diesel Exhaust Fluid (DEF) – a solution of urea and deionized water – into the exhaust stream of a diesel engine.

Common Problems with SCR Systems:

  • DEF Injector Issues - Injector can get clogged or crystalized from dried DEF.

  • DEF Heater Failure - DEF freezes in cold weather

and the heater fails to warm it up.

  • DEF Quality Issues - Using low-quality or contaminated DEF can damage the system.

  • NOâ‚“ Sensor Failure - One or both NOâ‚“ sensors fail (usually before and after SCR).

  • SCR Catalyst Deterioration - Catalyst becomes clogged, contaminated, or loses efficiency over time.

  • DEF Pump Problems - The pump that moves DEF from the tank to the injector can fail.

  • Control Module Faults - Communication or software errors in the SCR module (also called ACM – Aftertreatment Control Module).

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