Heavy-duty diesel component during service

Diesel Tuning & Emissions Repair

Aftertreatment & ECU Tuning — DOC, DPF, SCR, EGR, NOx

Call (931) 561-7736 Request service

Based in Russellville, KY · 75-mile radius

What we cover

  • Forced DPF regeneration when the truck has derated
  • DPF cleaning and back-pressure verification
  • DOC (Diesel Oxidation Catalyst) inspection and replacement
  • SCR (Selective Catalytic Reduction) catalyst service
  • EGR cooler replacement and coolant-leak diagnosis
  • EGR valve cleaning or replacement
  • DEF (urea) dosing system repair: pumps, lines, injectors, sensors
  • NOx sensor diagnosis and replacement (inlet + outlet)
  • Aftertreatment harness and sensor circuit diagnosis
  • DEF tank heater and quality sensor service
  • ECU calibration and diesel tuning for performance, drivability, and off-road builds
  • Emissions system delete service for off-road equipment and non-highway applications

How we handle it

When a truck is derated we start with the scan: which inducement, which fault codes, which sensor data. Often the truck is one stuck part — an inlet NOx sensor, a clogged DEF injector, a DPF that needs cleaned — away from running normally again. We confirm the failure, fix it, run the truck through a controlled regen if needed, and verify the system passes its inducement cycle. We don't replace expensive parts on guesses. NOx sensors are an $800 part — we test before we throw.

Parts & warranty

OEM NOx and DEF sensors where they belong; quality aftermarket DPFs when the cost difference matters and the part is up to spec. EGR coolers OEM. DEF pumps OEM. 1-year parts-and-labor warranty.

Related repairs

Other services

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Real work, real shop

  • Diesel particulate filter set on the ground after removal
  • Air brake chamber and S-cam viewed from under the chassis
  • Panasonic Toughbook running diesel diagnostic software
  • Engine control module on a workbench after removal

Frequently asked

What aftertreatment components do you actually work on?
DOC, 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. Whichever piece is bad, we have the scan tool, the parts channel, and the experience with that engine family — Cummins ISX/X15, Detroit DD13/DD15, Paccar MX, Mack MP8, Cat C15.
How long does DPF cleaning take?
If we can do a forced regen and clear the codes, an hour or two on-site. If the DPF is so plugged it needs to come off and go through a thermal/pneumatic cleaning machine, that's a 1–2 day turnaround through a regional cleaner we work with.
Why does my DEF light keep coming on?
Three usual suspects: DEF quality (a sensor saw bad urea), DEF dosing (the injector isn't spraying right), or a NOx sensor (the system thinks emissions are out of spec even when they're not). All three test cleanly with the right scan tool.
How much does an EGR cooler replacement run?
Most of the major engine families land in the $1,800–$3,200 range parts and labor depending on cab access. We give you a firm number after we confirm the cooler is the actual failure — coolant in the oil and coolant loss with no external leak are the usual triggers.

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

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