GM Engine Code Reference Chart(For All Engine Codes + Years)

General Motors (GM) has produced a wide range of engines over the decades, spanning from small block V8s to large diesel and performance engines. For car enthusiasts, mechanics, or anyone working on GM vehicles, understanding engine codes is essential.

Engine codes help identify the exact engine model, displacement, fuel system, and production year. This is crucial when ordering parts, performing repairs, or restoring classic vehicles.

GM Engine Code Reference Chart

Engine Code	Engine Type	Displacement	Fuel Type	Years Produced	Notes
L61	I4 Ecotec	2.0L / 2.2L	Gasoline	2000–2010	Chevrolet Malibu, Cobalt, Saturn Ion
LAF	I4 Ecotec	2.4L	Gasoline	2008–2015	Chevrolet Cruze, Malibu
LE5	V6	3.5L	Gasoline	2005–2007	Chevrolet Impala, Pontiac G6
LY2	V6	3.5L	Gasoline	2007–2011	Impala, Malibu, Pontiac G6
LFX	V6	3.6L	Gasoline	2009–2015	Direct injection, AFM
LY7	V6	3.6L	Gasoline	2007–2013	Mid-range V6 for multiple GM vehicles
LGX	V6	3.6L	Gasoline	2014–Present	Updated DOHC V6, SUVs, sedans
LMG	V6	4.3L	Gasoline	2007–2013	Trucks, SUVs
LP9	V6	3.6L	Gasoline	2007–2014	Flex-fuel capable
L33	V6	3.6L	Gasoline	2008–2015	High-output, SUVs & sedans
L43	V6	3.6L	Gasoline	2010–2015	Mid-size SUVs
LS1	V8	5.7L	Gasoline	1997–2004	Corvette, Camaro, Firebird
LS2	V8	6.0L	Gasoline	2005–2007	Performance V8, Corvette C6
LS3	V8	6.2L	Gasoline	2008–2017	Corvette, Camaro SS
LS4	V8	5.3L	Gasoline	2005–2009	FWD small-block variant
LS6	V8	5.7L	Gasoline	2001–2005	Corvette Z06, high-output
LS7	V8	7.0L	Gasoline	2006–2015	Corvette Z06 performance
LS9	V8 Supercharged	6.2L	Gasoline	2009–2013	Corvette ZR1
LSA	V8 Supercharged	6.2L	Gasoline	2009–2015	Camaro ZL1, CTS-V
LT1	V8	6.2L	Gasoline	2014–Present	Modern small-block, Corvette, Camaro
LT4	V8 Supercharged	6.2L	Gasoline	2015–Present	Corvette Z06, Camaro ZL1
LQ4	V8	6.0L	Gasoline	1999–2007	LS-based, trucks & SUVs
LQ9	V8	6.0L	Gasoline	2000–2006	High-output trucks, SUVs
LY6	V8	6.0L	Gasoline	2007–2014	Silverado, Tahoe, Escalade
L96	V8	6.0L	Gasoline	2007–2013	Vortec trucks & SUVs
LC9	V8	5.3L	Gasoline	2007–2013	Flex-fuel capable
LGZ	V8	5.3L	Gasoline	2014–Present	Active Fuel Management, Silverado/Sierra
Vortec 4800	V8	4.8L	Gasoline	1999–2013	Trucks & SUVs
Vortec 5300	V8	5.3L	Gasoline	1999–2013	Trucks, SUVs
Vortec 6000	V8	6.0L	Gasoline	2000–2014	Trucks & SUVs
Vortec 8100	V8	8.1L	Gasoline	2001–2009	Heavy-duty trucks
262	I6	4.3L	Gasoline	1982–1990	Classic inline-6 truck engine
305	V8	5.0L	Gasoline	1976–1988	Small-block, common in GM cars
350	V8	5.7L	Gasoline	1967–2003	Classic small-block V8
400	V8	6.6L	Gasoline	1970–1980	Big-block, cars & trucks
454	V8	7.4L	Gasoline	1970–1990	Big-block, Corvette, trucks
396	V8	6.5L	Gasoline	1965–1970	Classic performance engines
427	V8	7.0L	Gasoline	1966–1969	Corvette high-performance
502	V8	8.2L	Gasoline	1998–2007	Big-block crate engine, trucks
LWN	I4 Diesel	2.8L	Diesel	2013–2017	Chevrolet Colorado, GMC Canyon
Duramax LB7	V8 Turbo Diesel	6.6L	Diesel	2001–2004	Silverado HD
Duramax LLY	V8 Turbo Diesel	6.6L	Diesel	2004–2006	Silverado HD, GMC Sierra HD
Duramax LBZ	V8 Turbo Diesel	6.6L	Diesel	2006–2007	Heavy-duty truck engine
Duramax LMM	V8 Turbo Diesel	6.6L	Diesel	2007–2010	HD trucks
Duramax LML	V8 Turbo Diesel	6.6L	Diesel	2011–2016	HD trucks
Duramax L5P	V8 Turbo Diesel	6.6L	Diesel	2017–Present	High-output, HD trucks
Vortec 4200	I6	4.2L	Gasoline	2004–2009	Trailblazer, Colorado, SUV inline-six
Vortec 4300	V6	4.3L	Gasoline	1985–2013	Classic truck & van V6
Vortec 3500	V6	3.5L	Gasoline	2005–2007	Mid-size sedans & SUVs

Related LS Engine Identification Chart(For All LS Models)

How to Read GM Engine Codes

GM engine codes are not random. Here’s how they are typically structured:

1. Prefix Letter (L, LY, LS, LT) – Identifies engine family.
   • L series: Inline engines (I4, I6)
   • LS, LT: Small-block V8s
   • LY: V6 engines or newer V8s
2. Number – Indicates engine displacement or version.
3. Suffix/Letters – Optional, can signify high-performance or supercharged variants (e.g., LS9, LSA).

For example, LS3:

• LS = Small-block V8
• 3 = Third generation of high-performance small-block engines

Related Year to VIN Chart(From 1980–2069)

Tips for Using Engine Codes

1. Always verify with the VIN: Engine codes can change within the same vehicle year. VIN decoding ensures accuracy.
2. Take photos: When ordering parts, a clear photo of the engine code helps avoid mistakes.
3. Use official GM documentation: GM service manuals provide the most reliable cross-reference for codes.
4. Check performance variants: Codes like LS7, LS9, or LSA indicate high-performance engines and may require special components.

FAQs

How do I identify my GM engine?

To identify a GM engine, you can use several methods:

1. Check the engine block: Look for a stamped code on the front, side, or near the cylinder head. This is the official GM engine code.
2. Use the VIN: The 8th digit of the Vehicle Identification Number (VIN) indicates the engine type. Cross-reference this with an engine code chart.
3. Look for RPO codes: GM vehicles include Regular Production Option (RPO) stickers on the firewall or under the hood, listing engine codes.
4. Compare physical features: Certain engines have unique characteristics, like bolt patterns, intake manifolds, or valve covers, which can help with identification.

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What is the RPO code for GM engines?

RPO stands for Regular Production Option. GM assigns each engine a unique RPO code to identify engine type, displacement, fuel system, and features. For example:

• LS1 – 5.7L small-block V8
• LY2 – 3.5L V6
• L5P – 6.6L Duramax diesel

RPO codes are often listed on the build sheet, window sticker, or under-hood sticker, making them the most accurate way to identify a GM engine.

Which digit in a GM VIN is the engine code?

The 8th digit in a GM VIN represents the engine type. This digit can indicate:

• Engine family (V6, V8, I4, diesel)
• Displacement
• Sometimes special features (e.g., high-output, supercharged)

By combining the VIN digit with the engine block code or RPO, you can accurately identify your engine.

How to identify GM LS engines?

GM LS engines are a family of small-block V8s produced since the late 1990s. To identify them:

1. Check the engine code stamped on the block: LS engines are labeled LS1, LS2, LS3, LS6, LS7, LS9, LSA, etc.
2. Look for key features: LS engines typically have a coil-on-plug ignition system, rectangular intake manifold, and lightweight aluminum heads (on performance versions).
3. Use VIN or RPO codes: Vehicles equipped with LS engines will have the corresponding RPO code on the build sheet.

What are some common GM RPO codes?

Here’s a list of common GM RPO engine codes:

• LS1 – 5.7L V8 small-block
• LS2 – 6.0L V8
• LS3 – 6.2L V8
• LS6 – 5.7L high-output V8
• LS7 – 7.0L high-performance V8
• LFX – 3.6L V6
• LY2 – 3.5L V6
• LWN – 2.8L I4 Diesel
• L5P – 6.6L Duramax diesel

These codes are useful for ordering parts, performing repairs, or verifying engine authenticity.

How do I tell if my motor is a 350 or 305?

The GM 350 and 305 small-block V8 engines are very similar, but can be distinguished by:

1. Displacement markings: Many blocks have the displacement stamped on the front passenger side of the block.
2. VIN or RPO codes: The 8th VIN digit or RPO sticker can indicate whether it’s a 350 or 305.
3. Physical differences:
   • 305: 3.736-inch stroke, smaller intake manifold, thinner heads, often used in economy cars.
   • 350: 3.48-inch stroke, larger intake, thicker heads, used in performance and trucks.
4. Casting numbers: Look up the engine block casting number to verify exact displacement.