If you’re a fan of the great outdoors, or you simply like to escape the city on the weekends, we understand why a Subaru is your brand of choice. With their special flat boxer engines, and superior Japanese engineering, Subaru promises nothing but reliability & superiority.
Unfortunately, no engine in this world is 100% engine free, that includes the FA20 engine from Subaru.
Doing your own research is always a good idea. Especially when it comes to Subaru models, that can often be a bad second-hand deal since they carry a lot of problems. This is why we are here to pinpoint these problems and help you out with your future purchase.
First, we are going to cover the basic specs of the FA20 engine and learn more about the numbers that this engine delivers. Then, we are going to cover the common Subaru FA20 engine problems and see what troubles this engine and lastly, we are going to learn more about the models where you can find this engine.
Basic Subaru FA20 Engine Specs
The FA engine is a relatively new Subaru engine design. This engine was introduced in 2012 and is still widely used today.
This engine design is based on the FB20 and was jointly developed by Subaru and Toyota to serve in the Toyota 86 and the Scion FR-S.
What is interesting about the FA20 is that it was completely redesigned and except for the engine block, there are no similarities with the FB20 engine.
This new engine got a new crankshaft, new connecting rods, and new pistons. What is interesting about the displacement of this engine is that it has equal bore and stroke. This design makes the engine run extremely smoothly.
In addition to this, the FA20 has a higher compression ratio and variable valve timing, and most importantly, a direct injection fuel system designed by Toyota.
What is worth noting is that there are two versions, a naturally aspirated version and a turbocharged version.
The FA20 has the following specs:
- Configuration: Flat-4 Boxer
- Displacement: 2.0L
- Cylinder Bore: 86 mm
- Piston Stroke: 86 mm
- Block & Head Material: Aluminum
- Cylinder Head: DOHC, 4 valves per cylinder
- Compression Ratio: 12.5, 10.6 turbo version
- Direct Injection: Yes
- Aspiration: N/A & Turbocharged
- Horsepower: 200 – 300 hp
- Torque Output: 151 lb-ft – 295 lb-ft
Common Subaru FA20 Engine Problems
Common Subaru FA20 engine problems include:
- Bad Engine Tune
- Carbon Buildup
- Connecting Rod Failure
- Rocker Failure
- Valve Spring Failure
- Camshaft Gear Failure
Now that you know the problems of this engine, it’s time to elaborate on each of them and learn how these problems appear and how serious they are.
So, that’s what we are going to discuss next and find out more about the seriousness level of these issues and whether they are a dealbreaker for you. So, let’s dive in.
Bad Engine Tune
Many owners of the FA20DIT have complained that the factory tune that comes with the engine is not particularly good.
For those who don’t know, a tune is the software on which the engine is working. Modern engines are using computers to adjust the air-to-fuel ratio and deliver the power. So, the software is key in order for the engine to work properly.
Many of the owners noted that the factory tune is pretty aggressive on boost and the engine runs pretty rough. There is also a situation known as a lean air-to-fuel ratio. This is the case when the engine’s air-to-fuel ratio is more parts air and fewer parts fuel.
So, the solution to this problem is installing an aftermarket tune for this engine in order to make it work as intended.
You can also go to the dealership and let them do the job for you. Either way, this is an annoying issue that infuriated a lot of owners of this engine.
Although, a different thing probably causes this issue. Namely, direct injection. Direct injection cars tend to run like this, and the FA20 was the first engine in the Subaru lineup to use a system like this.
So, if we jump to conclusions, we can see where this problem goes. Overall, if you don’t want the factory tune, you can simply install an aftermarket tune and this will solve the problem.
Carbon buildup is a situation where you get black carbon deposits in the engine that are caused by the work of the engine.
This was not an issue in Subaru engines prior to the introduction of the FA20. Mainly because carbon buildup often occurs in engines that use direct injection.
So, the FA20 is the first engine that uses this technology. This means that it is susceptible to creating carbon deposits on the piston crown, as well as on the intake ports.
The carbon on the crown itself is not a problem. But carbon deposits on the intake port are really a problem.
These carbon deposits can become so excessive and prevent the valves from opening and closing correctly.
When this happens, you will have a serious problem because your engine will require cylinder head refurbishment which can cost a ton of money.
So, you should do a walnut blast every 60,000 miles in order to clean these deposits and return the engine back to normal.
Connecting Rod Failure
Connecting rod failures were also noted on the FA20 engine. So, what is a connecting rod, and why does it fail?
Connecting rod is the rod that connects the piston and the crankshaft. These rods that are used on the FA20 tend to fail catastrophically and destroy the engine in the process.
But what is worth noting is that these failures often happen on engines that are tuned and also working well above the factory-recommended spec.
The rods are a weak point on these engines and if you want to run high boost, we would recommend replacing the rods and pistons with aftermarket components. This might be more expensive but the engine will not destroy itself.
Now let’s move on to the next Subaru FA20 engine problems.
Engine rockers are another failure point on these engines. This is the case because these rockers are not held by anything.
Even with the smallest clearance between the cam lobe and the rocker, the rocker can fall off and destroy the cylinder head.
This is one small but fatal flaw that often happens on these engines. This is why we recommend installing rocker retainers besides the forged pistons and rods.
More on the problem, you can see in the video that we attached.
Valve Spring Failure
Another very common failure on these engines is the valve spring failure. So, what is a valve spring and what does it do?
A valve spring is a spring that holds the valves. The valve spring is compressed and this spring in many cases cannot take the stress and simply fails.
Whenever the spring fails, the engine can end up totaled. The engine will drop a valve and also there will be carnage in the cylinder head.
Overall, a very bad situation. This is a common problem on the early engines and Subaru has made a recall on 420,000 cars with the FA20 engine.
This is why you need to make sure that your vehicle was one of these models.
Camshaft Gear Failure
The camshaft gear on the Subaru FA20 engine can also fail and cause problems. The camshaft gear is the gear that is in charge of the variable valve timing. It is directly connected to the camshaft of the engine.
Whenever this problem appears, you will get a P0016 or a similar code that indicates a camshaft correlation problem.
The way around it is to replace the cam gear with a new one and this will solve the problem. It can be expensive but it is the only way around.
Which Subaru Has the FA20 Engine?
The following Subaru models have the FA20 engine:
- Scion FR-S
- Subaru BRZ
- Toyota 86
- 2012 – 2014 – Subaru Legacy 2.0GT DIT JDM
- 2012 – 2014 – Subaru Levorg
- 2012 – 2014 – Subaru WRX S4 JDM
- 2014 – 2018 – Subaru Forester USDM
- 2014 – 2018 – Subaru Forester JDM
- 2015 – 2021 – Subaru WRX USDM
What Are The Common Subaru FA20 Engine Problems?
Common problems on this engine include carbon buildup, rod failure, valve spring failures, cam gear failures, and rocker failures. There was a recall for the valve spring failures that occur on some of the engines. Other failures often appear when the engine is tuned and pushed to the limit.
Is The Subaru FA20 a reliable engine?
Yes, this engine is pretty reliable. The only downside is the valve spring failure which needs to be addressed. Besides that, the engine is pretty good. Problems only appear after you tune the engine and make it produce power well above the factory spec.