Chevy & GMC Truck Repair in Charleston, SC
Mobile diagnostics and repair for Chevrolet and GMC commercial trucks and vans — Duramax diesel and gas, Silverado, Sierra, Express, and Savana.
Chevy & GMC Service
Duramax diesel diagnosis done right
Chevrolet and GMC trucks powered by the Duramax diesel are among the most capable commercial platforms available — but aftertreatment system faults, injector issues, and electrical problems require accurate diagnosis. Lowcountry Diagnostics provides mobile Duramax service throughout the Charleston area.
Models We Service
Silverado, Sierra, Express, and Savana — diesel and gas
We service the full range of Chevrolet and GMC commercial trucks and vans in use across the Charleston area. This includes Silverado 2500HD and 3500HD pickup trucks and cab-chassis units used by contractors and service companies, GMC Sierra 2500HD and 3500HD in fleet and commercial configurations, and Chevrolet Express and GMC Savana 2500 and 3500 cargo and passenger vans.
Duramax diesel engines in our service scope include the current 6.6L L5P (2017–present), the 6.6L LML and LGH (2011–2016), the 6.6L LMM (2007.5–2010), the 6.6L LBZ and LLY (earlier generations), and the 2.8L LWN Duramax in Colorado and Canyon trucks. We also service gas-powered Silverado, Sierra, Express, and Savana units with 6.0L and 6.6L gas V8 engines.
Common Repairs
What we see most often on Duramax trucks
Duramax DPF & DEF System
L5P and LML Duramax trucks use DPF and SCR aftertreatment systems that generate fault codes for soot load, DEF quality, SCR efficiency, and NOx sensor readings. Accurate live data diagnosis is required before replacing sensors or catalysts.
EGR System & Cooler
EGR cooler leaks, EGR valve faults, and intake restriction from carbon buildup are common across multiple generations of Duramax engines. EGR cooler failures can allow coolant into the intake and result in engine damage if not addressed promptly.
Fuel Injectors & CP4 Pump
The CP4 high-pressure injection pump used in LML Duramax trucks is a known failure point. A failing CP4 can contaminate the entire fuel system. Diagnosing injection system faults accurately prevents unnecessary injector replacement.
Allison Transmission
The Allison 1000 series transmission used behind the Duramax is durable but requires proper fluid service and can develop shift quality issues and fault codes at high mileage or under hard commercial use.
Electrical & Module Faults
Check engine lights, ABS warnings, HVAC electrical issues, and body module faults are all common on higher-mileage Chevy and GMC commercial units. We diagnose across all systems, not just the powertrain.
Express & Savana Van Service
The Express and Savana cargo vans are workhorses that often get deferred maintenance. Engine, brake, electrical, and HVAC service on these vans keeps commercial fleets running without the downtime of waiting for a shop appointment.
Duramax fleet service in Charleston
Chevrolet and GMC trucks are a significant portion of the commercial vehicle population in the Charleston area. Contractors, service companies, utilities, and fleet operators rely on Duramax-powered trucks and gasoline vans for daily work. When a Duramax throws an aftertreatment code or a van develops an electrical issue, the impact on operations is immediate.
Lowcountry Diagnostics brings mobile Chevy and GMC service directly to your fleet location. We diagnose accurately, communicate clearly, and provide written documentation of every service call. For fleets with multiple Chevy or GMC units, our preventive maintenance programs keep each vehicle on a documented service schedule and catch developing issues before they take a unit off the road.
Clear Communication
Findings, options, and next steps you can act on
You should not have to guess what was checked, what failed, or what happens next. We explain the diagnostic findings, the likely cause, the recommended repair direction, and any follow-up items that should be watched or scheduled later.