What is the engine code for the Subaru Impreza?

[MacPatrick]

Subaru Impreza's engine code is EJ20. The arrangement methods of the engine are as follows: 1. L-type: Also known as an inline engine, where the cylinders are arranged in a straight line, side by side at the same angle to form a plane; 2. V-type: Divides all cylinders into two groups, arranging adjacent cylinders at a certain angle so that the two groups form two planes with an angle between them, appearing as a V shape from the side; 3. H-type: Also known as a horizontally opposed engine, a type of V-engine where the angle becomes 180 degrees; 4. W-type: Exclusive engine technology of Volkswagen, combining two V-engines to form another V-engine.

[DiPreston]

Talking about the Subaru Impreza's engines is absolutely fascinating—it's like characters in a game changing skins, with completely different engine codes across different eras. The most famous is the renowned EJ series, like the EJ207 (Japanese version) or EJ257 (US version) used in the ninth-gen Impreza WRX STi, with that iconic horizontally opposed engine sound. Earlier base models had naturally aspirated EA series engines, while later models, like those post-2011, switched to the FB series with the FB16 and FB20. And if we're talking about the special S20XB STi race engine, it's like a hidden Easter egg—though average enthusiasts rarely get to experience it. Just remember the prefixes EJ and FB, and you won't get confused!

[LeDelaney]

My neighbor's heavily modified Impreza runs an EJ207 engine, and every time he fixes it, I get to hear the stories. Since the 1990s, the Impreza has primarily used EJ-series four-cylinder turbo engines, with the code names following the versions—the GC/GD-era WRX used the EJ205, while the STi upgraded to the EJ207 or 257. Later, the regular models switched to naturally aspirated engines like the FB16/20, but the WRX and STi stuck with the turbo route. Interestingly, all Subaru engines are horizontally opposed, and the low center of gravity gives the Impreza cornering stability like a gecko climbing a wall. If you're into older cars, it's best to check the specific year's manual, because even though the 200-horsepower EJ205 and 300-horsepower EJ257 are just a code apart, their performance is worlds apart.

[DiMicah]

The clearest way to distinguish by generations: Classic GC/GF models used EJ18/20/22; post-2000 GD/GG switched to EJ205 (WRX) and EJ207 (STi); starting in 2006, GE/GH began adopting the naturally aspirated FB20 engine, but the high-performance versions still retained the EJ257 turbo engine. The most hardcore is the S20XB engine, exclusively for the track-focused STi Type RA, with red-top aftermarket parts that are painfully expensive. It's recommended to check the chassis number for confirmation, as JDM EJ207 and USDM EJ255 parts are not interchangeable in parallel imports.

[ValerieLee]

Last night while flipping through the repair manual, I noticed that the engine codes of the Impreza basically reveal their birth years. In the late 1990s, the EJ20K series was mostly used in Japanese-spec STi models; after 2004, the US-spec WRX used the EJ255, while the STi used the EJ257. The Japanese version stuck with the EJ207 until it was discontinued in 2014. After the generational change, the FB engine became more compact but had weaker modification potential, though the new FA series engines started being used in the WRX. Don’t be fooled by the 4S shop into using the wrong parts—the EJ207 pistons are forged, and the regular EJ255 can’t handle 2.0 bar of boost.

[KendraFitz]

A seasoned mechanic who has worked on over a dozen Imprezas taught me this: you can identify the model just by listening to the engine bay. The EJ20 series turbo engines have a distinctive hissing sound from the blow-off valve during acceleration, while the FB20 naturally aspirated engine runs as smoothly as boiling water. To pinpoint the exact model, check the cylinder head—the EJ207 is marked with 'DOHC 16VALVE,' and the FB20 is labeled with dual VVT. Pay special attention to the intercooler positions; the USDM EJ255 differs from the JDM EJ207, so make sure to match the intake kit accordingly when modifying. Lately, FB20 engines are commonly seen in scrapyards, offering much better fuel efficiency than the EJ series, though they lack that aggressive edge.