How to Keep Your DPF Clean and Avoid Costly Forced Regens

The Diesel Particulate Filter (DPF) is a critical part of your emissions system. It captures harmful soot and prevents it from entering the atmosphere—but it can also choke your truck's performance and fuel economy if it’s not properly maintained. At Harmon Truck Service in Sullivan, MO, we help truck owners and fleet managers keep their DPF clean and avoid the downtime, cost, and frustration of forced regens. 

Whether you’re hauling up I-44 or navigating back roads through the Ozarks, DPF problems will catch up with you. Here's how to stay ahead of them. 

What Is a DPF and Why Does It Get Dirty? 

A DPF (Diesel Particulate Filter) is part of your truck’s aftertreatment system. Its job is to trap particulate matter (soot) from the exhaust stream and burn it off during a process called regeneration. 

But here’s the catch… 

● Soot builds up faster in stop-and-go driving, short hauls, and extended idling ● Failed sensors or fuel issues can cause incomplete burns 

● If the DPF clogs too much, your engine may enter limp mode, reducing speed and power 

When your truck can’t perform a passive or active regen, it requires a forced regeneration—a manual cleaning process that takes time, equipment, and money. 

How to Keep Your DPF Clean and Operating Properly

1. Drive Long Enough for Passive Regeneration 

Your truck naturally burns off soot during highway driving—this is passive regeneration. It requires high exhaust temperatures that only occur at steady speeds. 

Tip: 

● Drive 30+ minutes at highway speed regularly 

● Avoid excessive idling during delivery stops 

This is especially important in smaller towns like Sullivan, MO, where short hauls can lead to repeated regen interruptions.

2. Keep Up With Fuel and Air Filter Maintenance 

Clogged air filters and contaminated fuel cause incomplete combustion, which increases soot production. 

Action Steps: 

● Replace air filters every 15,000–30,000 miles (or sooner in dusty conditions) ● Use high-quality diesel and change fuel filters on schedule 

● Avoid additives unless recommended by your engine OEM 

3. Watch for Early Warning Signs 

Don’t ignore the DPF warning light—it means your filter is nearing capacity. Waiting too long leads to higher temps, lower performance, and eventually a forced regen or filter replacement. 

Watch For: 

● Decrease in fuel economy 

● Longer cranking times 

● Drop in turbo boost or throttle response 

● Frequent regeneration cycles 

4. Get Regular DPF Cleanings 

Even if regens are working, ash from burned soot still accumulates in the filter and can only be removed with a DPF cleaning machine. 

Cleaning Interval: 

● Every 150,000–200,000 miles for most OTR trucks 

● More often for vocational trucks or local haulers 

At Harmon Truck Service, we offer full-service DPF cleaning and flow testing to ensure your filter is breathing freely. 

5. Fix EGR, Turbo, and Sensor Issues Promptly 

Problems upstream from the DPF—like leaking EGR valves, low turbo pressure, or bad temp/pressure sensors—can spike soot production and sabotage the entire regen process. 

Don't let one bad component ruin your aftertreatment system. We always check related components during DPF service to ensure your regen cycles succeed. 

The Real Cost of Ignoring DPF Maintenance 

When you don’t keep your DPF clean, you pay for it in multiple ways:

● Forced regeneration: $300–$600 per event 

● DPF replacement: $2,000–$10,000 depending on make and model ● Engine derate or shutdown: Lost loads, missed deadlines, and possible tow bills ● DOT violations: Failed emissions inspections or roadside checks 

Why Local Conditions in Sullivan, MO Matter 

Midwestern driving conditions bring unique challenges. In Sullivan and surrounding Missouri areas, you’re dealing with: 

● Frequent cold starts in winter 

● Dusty roads in ag and construction zones 

● Short hauls between towns 

All of these can reduce DPF effectiveness and cause soot to build up faster than usual. 

At Harmon Truck Service, we understand local routes, driving patterns, and climate—and tailor your maintenance accordingly. 

Learn more 

If you want your diesel truck to run clean, powerful, and problem-free, keeping your DPF clean is non-negotiable. Through regular driving, smart maintenance, and timely service, you can avoid costly forced regens and keep your truck on the road. 

Trust Harmon Truck Service in Sullivan, MO to clean, inspect, and maintain your DPF system the right way—before problems put you out of commission.