EJ255 Engine Problems – Is This WRX Engine Reliable?

EJ255 Engine Problems – Is This WRX Engine Reliable?

August 10, 2022 0 By CarGuy

Are you planning on getting a Subaru and you are interested in learning the EJ255 engine problems? If that is the case and you are in this situation, then you are at the right place because there will be a lot to cover on this topic.

Doing a proper research before you decide on spending a ton of money on a car should be one of your top priorities. Especially nowadays when prices of cars are going through the roof. You just don’t want to make a bad investment.

So, learning the possible issues that you might face beforehand should be really useful for you. Since all engines have some problems. Some of them are more problematic and some of them are less. So, getting the right engine is a really important thing. Just imagine how expensive some repairs are. You could easily end up paying thousands of dollars on mechanics that will want to rip you off. And I’m really serious about this.

This is why we will focus on the EJ255 engine in this article and learn everything about it. First, we will cover what the EJ255 is and what are the applications of this engine. Then, we are going to learn the specs as well as how one of these engines is assembled. Then we will cover more on the EJ255 engine problems as well as the EJ255 years to avoid. So, if you want to learn more, follow along till the end.

What Is The EJ255 Engine? – EJ255 Engine Problems

So, before we start dealing with more complex stuff like the EJ255, let’s first learn more about the basis of the EJ255 engine and what is this engine all about. I bet you all are really interested in knowing. So, let’s dig in.

So, what is the EJ255? Well, this engine is a legend. It is one of the best, if not the best engine that Subaru has ever put into production.

The EJ255 is probably one of the most powerful engines that Subaru is running on their cars. Except for the EJ257. But that is a different kind of beast that we will save for a different time.

EJ255 Engine Problems

What is worth noting is that this engine was originally designed only for the US and Canada markets. But even though it was greatly used since recently, it became phased out. And now it is only used on the Impreza and the Legacy outside America.

So, we can say that it is still in production to this day. This is rather insane for an engine considering that the first introduction of this engine was in the Baja Turbo model back in 2004.

This engine was included in a ton of other applications. But more about that, we are going to cover this in the following chapter where we are going to elaborate on this in-depth.

EJ255 Applications

Now let’s discuss more about the applications of this engine and learn in which applications you can find an EJ255. This is also quite a usable piece of information for you because you still want to know which Subaru models have this engine and if you plan to purchase one, you will not have to wander around. So, let’s list all of the models that have the EJ255.

The most notable example of a vehicle running the EJ255 is the Impreza. More precisely the WRX model. This engine was included in this model between 2006 to 2016.

The next most notable example is the EJ255 Forester. The EJ255 engine was also included in the SUV that Subaru offers. More precisely, the years between 2004 and 2013.

In addition to this, this engine was also included in the Legacy and Outback. The Legacy was running the EJ255 from 2005 to 2012 and the Outback was running this engine from 2005 to 2009.

The EJ255 also saw a short stint in the Baja Turbo from 2004 to 2006. What is interesting to know, is that this engine was also equipped in the Saab 9-2X for the 2006 model year.

Nowadays, the EJ255 is still included with the Legacy, Outback, and the Impreza for markets outside the US. For the US model, this engine was replaced with one that meets the regulations. But what about the EJ255 problems? More on that, we will cover in a bit.

EJ255 Specs – EJ255 Engine Problems

Now before we dive into the EJ255 problems, let’s take a look a the specs that this engine has. As you probably know, this engine has a ton of similarities with the EJ257. So, they share a lot of commonalities when it comes to the engine block.

As you probably know, this is not an inline or a V8 engine design. But a flat engine. This means that the pistons are laid out completely flat and the crankshaft is in the center of the engine. So, when the pistons are working. They resemble two boxers boxing with each other. Thus the name boxer engine.

The EJ255 engine has a 2.5L of displacement overall, more precisely 2,457cc. The cylinder bore of the engine is 3.92 inches and has a rod length of only 3.11 inches. This is by design because you cannot allow installing longer rods. Simply there is not enough space inside of the engine bay for this.

The compression of the engine is also quite low. Mainly because this is a turbocharged engine. The compression on the EJ255 is 8.4:1

When it comes to head design, we can say that this engine implements a double overhead camshaft design (DOHC). This means that there are two camshafts on top of the engine. One for the intake and the other for the exhaust. The engine is belt driven.

When it comes to the EJ255 horsepower, we can say that this engine creates from 210hp up to 265hp depending on the application. But what about the EJ255 engine problems? More on that we are going to cover in a bit.

EJ255 Weight

A lot of people are interested in learning the weight of the EJ255. But nobody can give a clear number since no one has weighed one precisely.

But the estimates from experienced Subaru owners are that the engine itself weighs about 400lbs with all the accessories. The transmission on the other hand weighs about 250lbs. So, in total when these two are paired with all the accessories attached, the total weight would be about 650lbs.

EJ255 Engine Assembly

Now let’s discuss another topic and that is the EJ255 engine assembly. Let’s learn how this engine gets assembled.

What is unfortunate is that if we try to explain everything, it will take ages to do so. This is why we will attach a video of how this is done the right way. Enjoy.

Differences Between EJ255 And EJ257

Now before we dive into the EJ255 engine problems, let’s take a look first at the differences between the EJ255 and the EJ257. In what ways do these two engines differentiate from one another?

As you probably know, the standard EJ255 was used on the WRX model. While the EJ257 was the engine used on the STi version. This means that this engine is more potent.

And this power was achieved by replacing the cylinder heads with better flowing heads. In addition to the change in head design. There were also some changes in the pistons. The pistons dish featured a taller piston dome and a deeper cylinder head.

All, these modifications allow the EJ257 to develop significantly more power than the standard EJ255 engine. Still, the EJ257 was only used on the STI version of the WRX. But what are the EJ255 engine problems? Well, more about the problems we are going to elaborate on next.

EJ255 Engine Problems

So, we learned the specs and the applications of the EJ255 engine. And we think that now it is time to move on and start discussing more about the EJ255 problems.

If you plan to buy a WRX or any other Subaru that has the EJ255 engine. The following chapters will be perfect for you and will help you familiarize yourself with the possible problems that this engine has. So, if you want to learn more, follow along.

1. EJ255 Turbo Problems

The first problem that we will discuss when it comes to the EJ255 is the issue with the turbo. Turbines tend to fail on these engines more often than on other engines. So, why is this the case?

The biggest reason why turbines fail is the mileage. These engines have been on the road for quite some time. So, they have 150,000+ miles on them and when you hit this mileage, it is very probable that you will soon have to rebuild the whole turbo.

Also, the turbine can fail because of oiling issues. The first thing that gets affected is the oil filter. The filter becomes clogged and the oil starts to bypass the oil filter. The turbo on the EJ255 is receiving oil through a banjo bolt that has a mesh on it. So, over a long time of use, this banjo bolt can be filled with oil deposits and the flow of oil will be reduced. And when the oil flow is reduced, the oil could cook off and the turbine will fail.

When a turbo fails you will experience some smoke from the exhaust. The turbine will start to produce a lot of noise and there will be a significant loss of powerful

Turbine replacement is rather expensive and could cost more than $1,500. So, when buying a used car, make sure that the turbo is all good. Now let’s move on to the next EJ255 engine problems.

2. Oil Consumption

The second most common problem in our list of EJ255 engine problems is increased oil consumption. Subaru engines love to drink oil.

After certain mileage, especially above 80,000 miles, you will start experiencing this problem and will notice how the levels of oil drop and you have to top off the oil. But why this problem happens?

Well, the short answer is bad oil control rings. Every piston has a ringland. And on this ringland there are three piston rings in total. The first two from top to bottom are compression rings, while the lowest one that looks a bit odd is the oil control ring.

This oil control ring has a special role in keeping the engine oil out of the combustion. But what can happen is that this oil control ring can fail and oil will start to go inside of the cylinder and will sludge out the pistons. Will make the compression rings also fail and stick inside of the ringland.

And when this happens, you will face issues like oil consumption, loss of power, loss of compression, and also black smoke from the exhaust. If the engine is drinking oil, the only way around this problem will be to perform an engine rebuild and sort out the problem. But this can be rather expensive and also, the engine should be in good condition. If not, you better get a new engine for this car. Now let’s move on to the next EJ255 problems.

3. Oil Leaks

The second in our list of EJ255 engine problems is the issue with the oil leaks. Subaru engines are really oily and greasy. So, why is this the case?

Well, this is primarily by design. The head gaskets instead laying flat or at some slight degree. They are vertically mounted on these flat engines.

So, gravity is doing its thing. And the valve cover gaskets, and head gaskets are starting to develop leaks and the engine gets really greasy.

Unfortunately, there isn’t a solution to this problem. Unless you decide to replace them if the leaks are too large and you are using a ton of oil. So, beware of this problem when looking for a car to buy. The leaks and the oil level will tell you a lot about the general condition of the engine. Now let’s move on to the next EJ255 engine problems.

4. Rod Bearing Failures

And the last type of EJ255 engine problems that we would discuss is the situation with the rod bearing failures.

These engines by design are pretty bad when it comes to proper oiling. So, they often suffer from oil starvation. Oil starvation is a situation when you have a low amount of oil in the engine and the oil simply cannot reach every part of the engine.

And when you have oil starvation, you have rod bearing wear. The rod bearings on these engines tend to wear quite more than on other engine designs.
And when the rod bearings fail, the pistons will get out of balance and there will be carnage inside of the engine. And this is a situation that nobody likes often known simply as rod knock. If the engine on the Subaru that you plan to buy starts to knock, stay away from it. You don’t need this problem in your life.

This engine is beyond repair and the only way around will be to purchase a new engine. Because once the engine starts knocking, there is no saving. This is also a really expensive problem to fix. Costing at least $4,500 to get a new engine.

5. Head Gasket Failures

And the last in our list of EJ255 engine problems is the problem with the head gaskets. This engine has two of them. One on each side. And these gaskets similarly to the valve cover gaskets that we covered are placed vertically. Plus on top of that, they are often manufactured of poor materials that fail very often. A Subaru engine without a blown gasket is something really rare. Like a unicorn.

But jokes aside. This problem is serious and can cost a ton of money to be fixed. Sometimes owners delay the repairs and the engine keeps losing coolant. And when this happens, the engine starts to overheat. And in this period, the head will start to warp.

Sometimes the engine head is so warped that it is not fixable anymore. And you need to get a new cylinder head if you want to sort out the problem. So, be really aware of an overheating engine. You don’t want this problem in your life. A head gasket replacement when purchasing a used engine is recommended.

EJ255 Reliability

So, is the EJ255 a reliable engine? Well, sort of. If you get a low mileage engine, then this engine will perform really well. But if you get a 150,000+ mile engine, you cannot expect much.

High mileage engines tend to have leaks and head gasket failures. Suffer from turbo problems and also from oiling problems. So, I would strongly advise making a small refresh of the engine when it reaches high miles. Replacing the gaskets, doing the timing belt and water pump, plus some other tweaks will make this engine bulletproof.

So, when it comes to these Subaru engines, you really have to put an effort in order to keep them afloat. Since if you are careless and you don’t do this maintenance, you risk destroying the engine.

EJ255 Years To Avoid

When it comes to the years to avoid, it is a rather difficult choice to make since all years perform pretty much the same. But if you really want to avoid some years, avoid the years from 2006 to 2012. Go for the last two years of production. These engines should be less worn out.

Or if you have to go for an early model, try to find one with relatively low mileage. This way you will be sure that there are no major problems.


In this article, we have covered quite a lot when it comes to the EJ255 engine. First, we learned what this engine is all about and its main specs. We have covered the applications in which this engine is included as well.

Then we learned about the EJ255 engine problems. As with other Subaru engines. The EJ255 also has its fair share of problems. So, you need to be prepared for that if you don’t want to end up with a basket case full of problems.


Is EJ255 A Turbo?

Yes, this engine is the turbocharged version of the EJ25 that is designed specifically for the North American market. This engine was included in the Impreza WRX, Legacy GT, Forester XT, Outback XT, and Baja Turbo.

What Is The Weakness Of The EJ255?

The EJ255 is similar to the regular EJ25 and has pretty much the same issues. These are problems with oiling, oil consumption, overheating, and head gasket failures. These engines tend to overheat a lot. Also, they consume a lot of oil and in the end, the rods will start knocking and the engine is destined for the junkyard. These engines just don’t last for a really long time like regular inline engines.

How Much HP Can A EJ255 Handle?

This engine can handle about 480 bhp with stock components. Even though the reliability after that will be questionable. So, if you want to achieve a lot of power with this engine, we would strongly advise that you go for a built motor. This way you will be sure that the reliability will not be under question.

What Are The Problems With The EJ25?

This engine has problems with the head gaskets, they tend to fail and the engine will start to lose coolant and will overheat. Other problems include internal engine wear. Especially on the rod bearings and this situation can basically destroy the engine.