GM Duramax 6.6L LGH Commercial Diesel: Specs, Engine Codes, Controllers & Maintenance
Engine Information · GM · Duramax · LGH
Duramax 6.6L LGH Commercial Diesel
The LGH puts Duramax torque to work in vans and selected chassis-cab trucks. Its commercial ratings, transmission pairing and calibration differ from an LML pickup, even though the engines share their basic 6.6L architecture.
Engine construction
| Specification | Details |
|---|---|
| Capacity / layout | 6,604 cc · 90° V8 |
| Bore × stroke | 103 × 99 mm |
| Construction | Cast-iron block · aluminum heads |
| Valve gear | OHV · 32 valves |
| Fuel / induction | Common-rail direct injection · variable-geometry turbo |
| Compression | 16.0:1 |
| Aftertreatment | EGR · DPF · SCR/DEF |
Codes & output
| RPO / version | Power / torque | Key difference |
|---|---|---|
| LGH van | 260 hp / 525 lb-ft | Savana / Express |
| LGH chassis cab | 335 hp / 685 lb-ft | Selected Sierra / Silverado commercial builds |
SAE horsepower; torque in lb-ft. Ratings are for the stated application and fuel, rather than every vehicle with this RPO.
Vehicles & model years
| Brand | Model | Model years | Platform / chassis | Engine RPO |
|---|---|---|---|---|
| GMC / Chevrolet | Savana / Express 2500/3500 | 2011–2016 | GMT610 | LGH |
| GMC / Chevrolet | Sierra / Silverado HD chassis cab | 2011–2012 selected chassis-cab builds | GMT900 | LGH |
U.S. and Canadian applications within the 2005–2026 matrix scope. Engine availability depends on trim, build date and emissions certification.
Engine controllers
| Application / revision | ECM or PCM | Identification & function |
|---|---|---|
| 2011–2014 LGH | Bosch E86A-family ECM | Commercial fuel, turbo and emissions calibration; confirm module service ID |
| 2015–2016 LGH | Bosch E86B-family ECM | Later commercial calibration; van and pickup files are not interchangeable |
| Transmission | Application-specific TCM | Van 6L90 and HD chassis-cab combinations must be identified separately |
Identify the module from its service number, operating-system ID and VIN. The ECM/PCM and transmission controller have separate calibrations on many applications; a matching RPO alone does not make a replacement module plug-and-play.
Common issues & maintenance
- High-pressure fuel-system contaminationHard starting, low rail pressure and metal debris can indicate pump damage. GM’s diagnostic bulletin calls for inspecting the regulator and addressing contamination throughout the system when confirmed; replacing only the pump can leave damaging debris behind.
- SCR / DEF and DPF warningsNOx sensors, reductant delivery, heaters and exhaust sensors can trigger reduced-power or service messages. Read the complete aftertreatment fault set and test the failed circuit before replacing the DEF tank or filter.
- Fuel supply and boost lossesRestricted filters, air entry and charge-air leaks can feel like a failing pump or turbo. Check actual versus requested pressure and boost under load.
Keep it healthy. Follow the VIN-specific oil and fuel-filter schedule, shortening service for towing, idling and repeated short trips where the manual requires it. Drain water from fuel when indicated, maintain the cooling stack and investigate falling rail pressure before replacing expensive fuel-system parts. Repeated idling and short urban work can increase aftertreatment demands; service by operating conditions as well as kilometres.
References & technical sources
| Source | Reference |
|---|---|
| GM applications & RPO diagnostic matrices | View source |
| EFILive GM diesel controller families | View source |
| EFILive controller variants | View source |
| GM PIP4949D: fuel-system contamination | View source |
| GM factory Duramax ratings | View source |
| GM 2013 matrix: LGH vans / LML HD trucks | View source |
