Heavy-duty diesel component during service

EGR & DPF Service

EGR Cooler, DPF, SCR & DOC Service — Aftertreatment Done Right

Call (931) 561-7736 Request service

Based in Russellville, KY · 75-mile radius

Symptoms we look for

You hear

· Engine running rough at idle
· Regen fan spinning hard for long stretches

You see

· Check engine light + derate indicator
· DPF light steady or flashing
· DEF light steady
· White-ish smoke under load (EGR cooler internal leak)
· Coolant loss without external leak (EGR cooler)

You smell

· Hot exhaust smell from a slow regen
· Sweet coolant smell from EGR cooler leak

What we cover

Forced DPF regeneration (parked regen)
DPF cleaning (back-pressure verification, off-truck thermal cleaning when needed)
DOC (Diesel Oxidation Catalyst) inspection and replacement
SCR (Selective Catalytic Reduction) catalyst service and replacement
EGR cooler replacement (high-frequency failure across major engine families)
EGR valve cleaning and replacement
DEF doser injector replacement
DEF pump replacement
DEF tank heater and quality sensor service
NOx sensor diagnosis (inlet and outlet) and replacement
Aftertreatment harness and connector repair
Emissions system delete service for off-road and non-highway applications

How we handle it

When a truck derates we plug in the scan tool and pull the inducement: which sensor, which threshold, which code. Most derates are one stuck part away from clearing. We confirm the failure, fix it, run the truck through a parked regen if needed, and verify the inducement cycle clears cleanly. We don't replace expensive sensors on guesses. NOx sensors are $700–$900 parts — we test the sensor and the circuit before we throw one in.

Parts & warranty

EGR coolers OEM (the gasket is what's failing on most replacements; aftermarket EGR coolers don't seat right on many engine families). DEF injectors and pumps OEM. NOx sensors OEM (the aftermarket ones we've tried come back with the same code). DPFs OEM or quality aftermarket when the cost differential justifies it. 1-year parts-and-labor.

Related services

Other repairs

Coverage by city

EGR & DPF Service on-site in the cities below. Each link goes to the per-city page with localized response details.

Request service

Request egr & dpf service

Tell us what's going on and we'll call you back. For roadside emergencies, the fastest path is to call (931) 561-7736.

Real work, real shop

Frequently asked

What aftertreatment components do you actually service?

DOC (Diesel Oxidation Catalyst), DPF, SCR catalyst, EGR cooler and valve, DEF tank + pump + doser + injectors, inlet and outlet NOx sensors, and the harnesses and connectors that tie them together. We carry scan-tool coverage for Cummins, Detroit, Paccar, Mack, and Cat — whichever piece is bad, we can isolate and fix it.

Why does my truck go into derate every couple of weeks?

Usually a marginal sensor or a partially-plugged DPF that the regen system keeps trying to clean. We can do a real diagnostic: scan-tool history, sensor live data, back-pressure measurement. Often the fix is a sensor replacement or a DPF cleaning.

How much does an EGR cooler replacement cost on a Cummins ISX?

Parts plus labor lands around $1,800–$3,000 depending on generation and cab access. We give you a firm number after we confirm it's the cooler (coolant loss without external leak + white smoke under load is the giveaway).

Can DPF cleaning be done on-truck?

A forced regen can. A full DPF cleaning where the filter is removed and run through a thermal/pneumatic cleaning machine is a 1–2 day off-truck process at a regional cleaner. We coordinate the swap with a loaner DPF when downtime matters.

What customers say

4.7 / 5 from 43 Google reviews

“Brennan was great — absolutely hire this guy. I own a local tree company in Goodlettsville and one of my work trucks broke down at short notice. He was able to get there within a day or two and diagnose it. My turbo went out on one of my vehicles — when I went to the dealership they told me the wait time was forever and the process would include taking the cab off, which wouldn't work well with my current setup. Within one day he was able to replace my turbo and get it running so I could get back in business. The job was really labor-intensive but he made quick work of it and it runs even better than it did before. He's now the main guy I go to.”

— Tyler M.
“We've used Blacktop Mobile Repair twice this month, and both experiences have been nothing short of amazing. They run a top-notch operation, and it really shows in the quality of service and professionalism they provide. Jacob, the service tech, went above and beyond to make sure our truck was taken care of. He even drove out of his way to make sure he had the exact part needed to fix the truck and get us back on the road quickly. That level of dedication and commitment is hard to find. As a trucking company, downtime is costly, and having a team like Brennan and Jacob we can rely on makes all the difference.”

— Matthew P.
“I've used these guys in the past for an air compressor installation. Jacob was great. And recently my alternator quit on the weekend. I called Jacob on a Saturday and he helped me find one that I could pick up myself. Both times Jacob was knowledgeable & fair. A few months later — again on a Saturday — I wasn't even in their area and I called again to get troubleshooting advice. They are very good at diagnosing. Was able to pinpoint the trouble. Thanks again guys!”

— Dennis W.

Read all 43 reviews on Google