The L-series is a type of 4-cylinder engine created by Honda. It has 1.2, 1.3, and 1.5 L displacement variants, which utilize the names L12A, L13A, and L15A. Depending on the region, these engines are sold throughout the world in the 5-door Fit/Jazz hatchback and the 4-door Fit Aria/City sedan (also known as Fit Saloon). They are also sold in the Japanese-only Airwave wagon and Mobilio MPV.

Two different valvetrains are present on this engine series. The L12A, L13A, and one of the L15A varieties use i-DSI, or “intelligent Dual & Sequential Ignition”. This setup utilizes 2 spark plugs per cylinder. They fire at different intervals during the combustion process to achieve a more complete burn of the gasoline. This process allows the engine to have more power while keeping fuel consumption low thanks to the better utilization of gasoline. Emissions are also reduced. The i-DSI engines have a modest redline of only 6000 rpm, but reach maximum torque at mid-range rpm, allowing for decent performance without having to rev the engine at high speeds.

The other valvetrain in use is the VTEC on one of the two varieties of the L15A. This engine is aimed more at performance than efficiency with a slightly higher redline, which reaches peak torque at higher rpm. However, it still offers a good combination of both performance and fuel efficiency. Both the i-DSI and VTEC have relatively high compression ratios at 10.8:1 and 10.4:1, respectively.

Before April 2006, all vehicles sold with an L-series engine will have had a 5-speed manual or a continuously variable transmission (CVT) automatic available. However, the introduction of the Fit in Canada and the United States will be the first time an L-series engine has been mated to a traditional automatic transmission with a torque converter. The L12A i-DSI is available exclusively in the European domestic market Jazz and is sold with only a 5-speed manual transmission. The three other engines are available with a 5-speed manual, a CVT, a CVT with 7-speed mode, or a 5 speed automatic transmission, depending on the region.

L-series

L12A i-DSI

Available exclusively in the European domestic market Jazz (known as Fit in certain markets) and available with only a 5-speed manual transmission.
- Displacement: 1246 cc
- Bore x Stroke: 73.0 x 74.4 mm
- Compression Ratio: 10.8:1
- Horsepower: 57 kW (76 hp) @ 5700 rpm
- Torque: 110 N·m (81 lbf·ft) @ 2800 rpm
- Variations: L12A1

L13A i-DSI

Sold as a 1.3 in the Japanese Fit and only available with the standard CVT. European version marketed as a 1.4 for the Jazz and City, and available with either 5-speed manual or CVT with 7-speed mode. Available in other markets as well. European Civic 1.4 i-DSI has a standard 6-speed manual with an available 6-speed automated manual I-SHIFT transmission.
- Displacement: 1339 cc
- Bore x Stroke: 73.0 x 80.0 mm
- Compression Ratio: 10.8:1
- Horsepower: 63 kW (84 hp) @ 5700 rpm
- Torque: 119 N·m (88 lbf·ft) @ 2800 rpm
- Variations: L13A1 (Fit/Jazz), L13A7 (European market Civic), L13A8 (European market City)

L15A i-DSI

Available in the Fit Aria, Mobilio, and Partner in Japan. Offered in the Fit/Jazz and City in certain countries.
- Displacement: 1496 cc
- Bore x Stroke: 73.0 x 89.4 mm
- Compression Ratio: 10.8:1
- Horsepower: 66 kW (89 hp) @ 5500 rpm
- Torque: 131 N·m (97 lbf·ft) @ 2700 rpm

L15A VTEC

L15A1's Engine Bay (original engine, does not include custom vtec pipe,hks ground power system and air filter)

Available in the Fit, Fit Aria, Airwave, Mobilio, and Mobilio Spike in Japan. Sold throughout the world with 5-speed manual or CVT options in the Fit/Jazz and City. Canadian and US Fit models will have a 5-speed automatic instead of the CVT.
- Displacement: 1496 cc
- Bore x Stroke: 73.0 x 89.4 mm
- Compression Ratio: 10.4:1
- Horsepower: 81 kW (109 hp) @ 5800 rpm
- Torque: 143 N·m (105 lbf·ft) @ 4800 rpm
- Variations: L15A1 (Fit/Jazz)