6.6L Duramax engines by year

By CarWhere Research · Updated

GM has built six generations of the 6.6L Duramax V8 diesel: LB7 (2001–2004, VIN digit 1), LLY (2004.5–2006, 2), LBZ (2006–2007, D), LMM (2007.5–2010, 6), LML (2011–2016, 8) and L5P (2017–present, Y). Check the 8th VIN digit or the RPO code on the glovebox label to confirm which one a truck has.

Every Duramax shares the same 6.6-liter displacement and 103 × 99 mm bore and stroke, but each generation changed the fuel system, turbo and emissions hardware. The LB7 and LLY used a CP3 pump and no particulate filter, the LBZ added the six-speed Allison, the LMM brought the first DPF, the LML added DEF and the CP4.2 pump, and the L5P moved to a Denso fuel system, a BorgWarner turbo and, from 2020, a 10-speed Allison. Output has climbed from 300 hp and 520 lb-ft to 470 hp and 975 lb-ft.

Each generation has one issue worth checking first: injectors on the LB7, overheating and head gaskets on the LLY, pistons on modified LBZ engines, DPF and EGR hardware on the LMM, the CP4.2 pump on the LML, and emissions sensors on the L5P. Vans and chassis cabs also used lower-rated versions, including the LGH (VIN digit L) in 2011–2016 Express, Savana and chassis-cab trucks.

6.6L Duramax generations compared

6.6L Duramax generations: model years, peak GM-published output and documented problems
EngineModel yearsPeak hpPeak torque (lb-ft)Documented problemsRecalls
LB7 Duramax2001–200430052021
LLY Duramax2004.5–200631060530
LBZ Duramax2006–200736065030
LMM Duramax2007.5–201036566030
LML Duramax2011–201639776521
L5P Duramax2017–2023 · 2024–present47097525

LB7 Duramax

The LB7 is the first 6.6L Duramax, used in 2001–2004 Chevrolet Silverado and GMC Sierra heavy-duty pickups and identified by an 8th VIN digit of 1. It is rated 300 hp and 520 lb-ft. Its best-known weakness is fuel injectors, which GM covered under a since-expired 7-year/200,000-mile special policy.

LB7 Duramax specs, problems and recalls

LLY Duramax

The LLY is the second-generation 6.6L Duramax, used from mid-2004 through 2006 in Silverado and Sierra heavy-duty pickups and identified by an 8th VIN digit of 2. It is rated 310 hp and added a Garrett variable-geometry turbo and EGR. Its best-known weakness is overheating while towing, followed by head gaskets.

LLY Duramax specs, problems and recalls

LBZ Duramax

The LBZ is the third-generation 6.6L Duramax, used in 2006 and 2007 (Classic body) Silverado and Sierra heavy-duty pickups and identified by an 8th VIN digit of D. It is rated 360 hp and 650 lb-ft, was the first Duramax paired with the six-speed Allison 1000, and is the last one built without a diesel particulate filter.

LBZ Duramax specs, problems and recalls

LMM Duramax

The LMM is the fourth-generation 6.6L Duramax, used in 2007.5–2010 Silverado and Sierra heavy-duty pickups and identified by an 8th VIN digit of 6. It is rated 365 hp and 660 lb-ft and was the first Duramax with a diesel particulate filter, which is where most of its ownership issues come from.

LMM Duramax specs, problems and recalls

LML Duramax

The LML is the fifth-generation 6.6L Duramax, used in 2011–2016 Silverado and Sierra heavy-duty pickups and identified by an 8th VIN digit of 8. It is rated 397 hp and 765 lb-ft and was the first Duramax with SCR and diesel exhaust fluid. Its best-known concern is the Bosch CP4.2 high-pressure fuel pump.

LML Duramax specs, problems and recalls

L5P Duramax

The L5P is the current 6.6L Duramax, used in Silverado and Sierra heavy-duty pickups since the 2017 model year and identified by an 8th VIN digit of Y. It was rated 445 hp and 910 lb-ft through 2023 and 470 hp and 975 lb-ft from 2024. The Allison 10-speed replaced the six-speed for 2020.

L5P Duramax specs, problems and recalls

Related GM research

Confirm which 6.6L Duramax a truck was built with.

The engine RPO (for example L5P) is recorded against the VIN. The CarWhere build sheet decodes a Chevrolet VIN into the factory-ordered option codes on record — engine, transmission, axle and packages. $9.99, instant.

Chevrolet build sheet by VIN

Frequently asked questions

How can I tell which Duramax I have?

Check the 8th digit of the VIN: 1 = LB7, 2 = LLY, D = LBZ, 6 = LMM, 8 = LML, Y = L5P. The RPO code on the glovebox or spare-tire label confirms it.

Which Duramax years have a DPF?

Every Duramax from the 2007.5 LMM onward has a diesel particulate filter. The LB7, LLY and LBZ do not.

Which Duramax engines use DEF?

The LML (2011–2016) and L5P (2017–present) use SCR with diesel exhaust fluid. Earlier Duramax engines do not.

Which Duramax has the CP4 pump?

The 2011–2016 LML uses the Bosch CP4.2. The LB7 through LMM use the CP3, and the L5P uses a Denso HP4.

What is the most powerful Duramax?

The 2024-and-later L5P, rated 470 hp and 975 lb-ft in Silverado and Sierra HD pickups.

Sources

Figures come from the individual engine pages, each of which cites GM-published ratings and NHTSA records as listed below.

  1. Duramax History, Lesson 1: LB7 — Drivingline
  2. A Brief History Of Duramax Engine Specs — Diesel Army
  3. LB7 injector TSB (Special Coverage 04039B text) — The Truck Stop forum (secondary reference)
  4. 2001–2004 Chevy/GMC Duramax LB7 Fuel Injector Warranty Extension — The Diesel Page (secondary reference)
  5. Duramax History, Lesson 2: LLY — Drivingline
  6. Duramax V8 engine — Wikipedia (secondary reference)
  7. Duramax History, Lesson 3: LBZ — Drivingline
  8. 6.6L Duramax Diesel VIN ID Chart — DieselHub (secondary reference)
  9. Duramax History, Lesson 4: LMM — Drivingline
  10. GM Announces Best-in-Class Power Figures for 2011 6.6-Liter Duramax V-8 Diesel — Cars.com
  11. Duramax History, Lesson 5: LML — Drivingline
  12. 2011 Chevrolet Silverado HD (GM press information) — Serious Wheels
  13. GM Diesel Fuel Pump Class Action Lawsuit Settlement Final — CarComplaints.com
  14. CP4 Fuel Pump Defect – GM (case page) — Hagens Berman
  15. Official: 2017 Chevrolet Silverado HD Rated At 445 Horsepower And 910 Pound-Feet Of Torque — GM Authority
  16. Duramax History, Lesson 6: L5P — Drivingline
  17. GMC Sierra And Yukon Get Duramax Diesel DEF Sensor Fix — GM Authority
  18. 2024 Silverado HD (press release, Sept. 2022) — Chevrolet Pressroom
  19. Everything You Need To Know About The 2024 L5P Duramax Engine — Diesel Army

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Independent reference compiled by CarWhere — not affiliated with or endorsed by General Motors. Chevrolet, GMC, Cadillac, Corvette, Duramax, Vortec and the model names are trademarks of their owner.