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OnTec Innovations Inc. — On-Truck Emissions Cleaning

DPF 101

What is a DPF?

A plain-language guide to diesel particulate filters — what they do, the warning signs of trouble and what usually causes it.

Based in Baden, Ontario · 24/7 mobile service

DPF 101

What is a DPF?

A Diesel Particulate Filter (DPF) is part of a diesel engine's emissions system. It's designed to capture particulate matter — soot — from the exhaust before it leaves the tailpipe.

Over time, soot and ash accumulate inside the filter. Depending on the condition of the vehicle, the system may need a regeneration, diagnostics or professional cleaning to keep exhaust flowing the way it should.

Regular maintenance and a proper diagnosis when warnings appear can help you avoid unnecessary downtime — and avoid paying for the wrong fix.

Soot

Unburned carbon from combustion. Normally burned off during regeneration — if the truck gets the chance to complete one.

Ash

Non-combustible residue, largely from engine-oil additives. Regeneration can't burn it off, so it builds up until the filter is cleaned.

Typical exhaust aftertreatment
  1. ENG

    Engine

    Combustion produces exhaust that carries soot (particulate matter).

  2. DOC

    Diesel Oxidation Catalyst

    Treats exhaust gases and helps create heat used for regeneration.

  3. DPF

    Diesel Particulate Filter

    Traps soot and ash. Soot is burned off during regeneration; ash stays behind and builds up.

  4. SCR

    Selective Catalytic Reduction

    Uses DEF to reduce NOx before exhaust leaves the system.

Exhaust flows top to bottom. Layout shown is typical of many modern heavy-duty diesels — the exact arrangement varies by manufacturer and model year.

What can cause DPF problems?

  • 01Short-trip operation
  • 02Excessive idling
  • 03Failed regenerations
  • 04Engine / emissions faults
  • 05Excessive soot accumulation
  • 06Ash accumulation
  • 07Sensor / system issues
  • Often it's a combination — which is why diagnosis comes first.
Close-up of a red semi truck hood with a chrome emblem and dark mesh grille

Restricted exhaust flow costs you time, fuel and power.

Know the warning signs

When your DPF is clogged,your truck pays the price.

A diesel particulate filter is built to trap soot. When it loads up faster than it can clean itself, exhaust backs up — and the truck starts letting you know.

  • DPF warning light
  • Frequent regenerations
  • Failed regenerations
  • Reduced engine performance
  • Increased fuel consumption
  • Excessive backpressure
  • Check engine / emissions warnings
  • Derate conditions
  • Loss of power

Not every symptom means a bad DPF. These signs can point to an emissions or aftertreatment issue, but sensors, regeneration faults and engine problems can cause them too. Proper diagnostics should determine the actual cause — we'll help you work out the right next step.