If you ever find yourself staring at a 2015 wrx engine bay, the first thing you'll probably notice is just how much changed from the previous generation. This was the year Subaru decided to move away from the aging EJ series engine for the WRX and introduced the FA20DIT. For some purists, it was a hard pill to swallow, but for the average person who likes to turn their own wrenches, it brought some pretty welcome changes. It's a busy-looking space, full of plastic covers, hoses, and that signature top-mount intercooler, but once you get past the initial clutter, everything starts to make a lot more sense.
The Big Layout Shift
One of the most obvious things about the 2015 wrx engine bay compared to its predecessors is the turbocharger placement. In the older models, the turbo sat up high near the firewall on the passenger side. In this 2015 layout, the twin-scroll turbo is tucked way down at the bottom of the engine. This was a smart move for center of gravity, but it also means the exhaust manifold (the "headers") looks completely different.
Because the turbo is low, you don't have that massive heat source sitting right next to your brake lines and firewall anymore. However, it does mean that if you ever want to swap the turbo, you're going to be spending a lot more time under the car rather than leaning over the fenders. The top-mount intercooler is still there, dominating the center of the bay, catching air from the hood scoop to keep those intake temps down. It's a classic Subaru look, even if the engine underneath is more modern.
The Best Feature: That Oil Filter
If you've ever owned an older Subaru, you probably remember the "ring of fire." That was the nickname for the oil filter location, which was surrounded by scorching hot exhaust pipes. In the 2015 wrx engine bay, Subaru finally gave us a gift: the top-mounted oil filter. It's sitting right there on the top left (driver's side) of the engine, surrounded by a little catch basin.
Doing an oil change on this car is almost a joy. You don't have to go fishing around in the dark, and you don't have to worry about hot oil running down your arm. You just unscrew it from the top, pop a new one in, and you're good to go. It's probably the most "human-friendly" design choice Subaru made for this chassis.
Dealing with the Plastic and the Clutter
Let's be honest: the stock 2015 wrx engine bay has a lot of plastic. There's a large engine cover that hides most of the actual machinery. Most enthusiasts pull that thing off the second they get the car home. Underneath, you'll find a maze of vacuum lines and the sound symposer.
The sound symposer is that weird tube that runs from the intake tract over to the firewall. Its only job is to pump engine noise into the cabin so you can hear the car better. While it works, it's a major source of "clutter" in the bay. A lot of people choose to delete it with a simple plug kit. It cleans up the left side of the engine bay significantly and makes it much easier to see what's actually going on with your intake manifold.
Essential Maintenance Spots
Beyond the oil filter, there are a few other areas you'll want to keep an eye on. The battery is sitting right there in the front right corner. It's easy to access, but because of the way the FA20 handles its charging system, these batteries tend to take a beating. If your WRX is still running the original battery from 2015, you're definitely on borrowed time.
Then there's the airbox on the passenger side. Changing the air filter is a bit of a squeeze because of how tight the plastic housing fits against the frame rail, but it's manageable. Just make sure those metal clips are seated correctly when you close it back up, or you'll end up with a vacuum leak that'll drive your ECU crazy.
One thing that's still a bit of a pain? The spark plugs. Even though the 2015 wrx engine bay feels a bit more spacious than the old ones, it's still a boxer engine. The heads are pointed directly at the frame rails. You've only got a few inches of clearance to get the coils out and the plugs swapped. It's a "do it by feel" kind of job, and you'll definitely want a variety of swivel extensions for your socket wrench.
Popular Upgrades for a Cleaner Look
If you spend any time on forums or at car meets, you'll see that people love to "dress up" their 2015 wrx engine bay. Because it's so plastic-heavy from the factory, adding some metal bits can really change the vibe.
- Fender Shrouds: These cover the gaps between the inner fenders and the engine. They hide the messy bolts and clips and give the bay a much wider, more "finished" look.
- Pulley Covers: Replacing that black plastic alternator cover with a powder-coated aluminum one from a company like Perrin or GrimmSpeed is a rite of passage for WRX owners.
- Air Oil Separators (AOS): This isn't just for looks; it's almost a necessity for the FA20 engine. Since this is a direct-injection engine, it's prone to carbon buildup on the intake valves. An AOS helps keep oil vapors out of your intake tract, keeping the engine running cleaner for longer. It usually sits right near the pitch stop mount or the battery, adding a bit of a mechanical, high-performance look to the bay.
Tips for Keeping It Clean
A dirty 2015 wrx engine bay isn't just an eyesore; it can actually make it harder to spot leaks or issues before they become disasters. However, you can't just go in there with a pressure washer and spray everything down. There are too many sensitive sensors and electrical connectors.
The best way to clean it is to wait until the engine is cool, cover the alternator and the battery with some plastic bags or foil, and use a dedicated engine degreaser. Use a soft-bristled brush to agitate the dirt on the plastic covers and the intake manifold. Instead of a high-pressure blast, use a gentle mist from a garden hose to rinse it off. Once you've dried it with a microfiber towel or a leaf blower, you can use a plastic protectant (something matte, not greasy) to make those hoses and covers look like they just rolled off the assembly line.
Final Thoughts on the VA Engine Bay
Working in a 2015 wrx engine bay is a bit of a learning curve if you're used to traditional inline-fours or older Subarus. It's tight in some spots and surprisingly open in others. The transition to the FA engine brought a lot of modern tech, which means more sensors and wires, but the trade-off in reliability and ease of basic maintenance (like that oil filter!) makes it a pretty decent place to spend a Saturday afternoon.
Whether you're just checking your fluid levels or you're planning a full stage 2 build with a new J-pipe and intake, getting familiar with this layout is key. It might look intimidating at first glance, but once you start identifying the components, you'll realize it's actually a pretty logical setup. Just watch your knuckles when you're doing those spark plugs, and you'll be just fine.