6.6L DURAMAX • LB7 • LLY • LBZ • LMM • LML • L5P
Chevy and GMC Duramax trucks are built to work, tow, and rack up miles. When yours starts losing power, throwing an emissions warning, developing a fuel system issue, or just doesn't feel right, finding the actual cause matters.
Knox Performance Diesel & Offroad specializes in Duramax diagnostics, maintenance, repair, and performance in Killeen, Texas. We work on Duramax platforms from the LB7 through the L5P, using proper testing and diagnostics before recommending repairs.
From fuel system and injector concerns to turbochargers, DEF/DPF/EGR systems, cooling systems, Allison transmissions, oil leaks, electrical issues, steering and suspension, and major engine repairs, our goal is simple: find the problem and fix it right.
Check engine lights, intermittent concerns, electrical faults, drivability issues, and warning messages all start with proper diagnostics and testing.
From fuel contamination and injector concerns to low rail pressure, CP3/CP4 fuel system issues, hard starts, and drivability concerns, we properly test the Duramax fuel system before recommending repairs or replacing parts.
Loss of power, turbocharger faults, vane position codes, boost leaks, and drivability concerns can all affect performance
Cooling system concerns can quickly become costly repairs. We diagnose coolant leaks, water pump failures, thermostats, radiators, and overheating concerns
Oil leaks can originate from several different locations. We identify the source of the leak and recommend the appropriate repair before replacing parts unnecessarily
We diagnose and repair DEF, DPF, SCR, EGR, NOx sensor, regeneration, derate, and emissions-related concerns on modern Duramax trucks.
Not every engine concern requires a complete replacement. Our team performs the testing needed to identify the root cause and help you make an informed decision. From oil consumption and cooling system concerns to major engine failures and replacements, we'll help you determine the best option for your truck
From worn ball joints and tie rods to steering concerns, uneven tire wear, vibrations, and suspension wear, our team helps keep your truck driving safely and handling properly. Whether your truck is stock, used for towing, or equipped with aftermarket suspension components, we'll identify the root cause and recommend the repairs needed to keep it performing its best
From Allison transmission concerns and fluid services to transfer case leaks, shifting problems, towing-related wear, and driveline concerns, we diagnose and repair the systems responsible for getting Duramax power to the ground.
Modern Chevrolet and GMC trucks rely heavily on electronics and communication networks. We diagnose wiring, sensor, module, and electrical concerns before replacing part
Oil changes, fuel filters, transmission services, coolant flushes, differential services, and mileage based maintenance designed to keep your truck reliable.
Schedule your Cummins diagnostic, repair, or maintenance appointment with Knox Performance Diesel & Offroad in Killeen, Texas.
Knox Performance Diesel and Off Road
126 South Park Street, Killeen, Texas 76541, United States