Duramax VIN Code Chart – 8th Digit Defines Engine Code
Over the years Duramax engines have evolved greatly, and now have many year models that are crossover, or transitional. The easiest way to tell the exact Duramax model is by the VIN code. The 8th digit in the VIN code will tell you the Duramax model such as LLY or LBZ.
Which Duramax engine do I have?
First created in 2001, was the Duramax 6.6L Turbo Diesel “LB7” with 300 hp and 520 lb-ft of torque in ¾ and 1-ton trucks. GM then released the LLY halfway through 2004, with 310 hp and 605 lb-ft torque. The valve design was improved, making the injectors more accessible for repair. A variable-geometry turbo was added, to change the volume of air on the exhaust side of the turbo. Emissions were addressed, and an exhaust gas recirculation (EGR) system was added.
In 2006, the LBZ engine was introduced, producing 360 hp and 650 lb-ft of torque. This engine has a stronger block and piston design, with larger connecting rods, and heads that are designed to handle more pressure. They improved the turbo and put a larger EGR system. This is the last Duramax with an exhaust system that could be altered while keeping the truck street legal.
In 2007, the LMM was released, with 365 hp and 660 lb-ft of torque. The LMM was the first engine to be fitted with a diesel particulate filter (DPF). The DPF reduced fuel mileage, and dramatically reduced the amount of pollution produced by the engine.
In 2010, GM introduced the LML Duramax engine, with 397 hp and 765 lb-ft of torque. This engine has multiple new features including piezo-controlled injectors, a ninth injector to help DPF regeneration, a new EGR system with cooler bypass, and a new selective catalytic reduction (SCR) system with urea injection. The LML also has an exhaust brake built into the turbo, that can be activated by the driver with a button on the center console.
In 2011 a detuned version of the LML engine was released, with 260 hp and 525 lb-ft of torque. This was called the LGH and was not available in the pickup trucks.
In 2017, The L5P was released. This was the first total redesign of the engine, with 445 hp and 910 lb-ft of torque. This engine was designed with changes aimed at improving fuel economy, durability, and emissions.
You can find the VIN number on the vehicle’s driver side dash plate, the driver’s side door pillar, and/or your registration card.
The Duramax engine code is the 8th digit of the VIN number. For example, if the 8th number in your VIN code is 1, your Duramax would have an original LB7 engine. You can reference the different options in the chart below. The 10th digit of the VIN stands for the model year that you have. For example, if the 10th digit is 5, your Duramax would be 2005. By knowing these two simple tricks, you should be able to find exactly what engine your Duramax has, and what parts you will need for it.
Duramax VIN Code Chart
| Model Year(s) | 8th Digit of VIN Code | Duramax Model & Notes |
| 2001 – 2004 | 1 | LB7 |
| 2004.5 | 2 | LLY (introduced mid-year 2004) |
| 2005 | 2 | LLY (only engine offered for 2005) |
| 2006 | 2 | LLY (2006 version, different from 2005 version) |
| 2006.5 | D | LBZ (introduced late 2006) |
| 2007 | D | LBZ |
| 6 | LMM | |
| 2008 – 2010 | 6 | LMM (only Duramax offered during these years) |
| 2011 – 2016 | 8 | LML |
| L | LGH (not available in pickups) | |
| 2017 – 2022 | Y | L5P |
