4 Common Subaru Engine Problems That Cause Failure

4 Common Subaru Engine Problems That Cause Failure

December 30, 2023 0 By CarGuy

Are you looking to purchase a Subaru with the EJ-Series or a similar boxer engine? If that’s correct, you are in the right place because in this article there will be a lot to cover on the common Subaru engine problems.

Doing good and thorough research is always a good idea, you just don’t want to end up buying an unreliable engine that will drain your wallet and your nerves. This is why we are here to pinpoint these problems for you.

So, what are we going to learn? In this article, we are going to share all the common Subaru engine problems and see more about the Subaru engine reliability. So, let’s get started!

Subaru Boxer Engines Basics

Before we dive into the Subaru engine problems, let’s take a look at the boxer engine first and learn more about this design.

For those who are new to cars, this is the engine design that Subaru is using since forever. The boxer as its name implies is an engine where the crankshaft is located in the center and the pistons are laid out flat on both sides.

From a side perspective it looks like two boxers are exchanging punches, thus the name boxer.

And this design is really good. These engines are often very quiet and don’t make vibrations. They are placed down low in the engine bay and improve the center of gravity. Making cars with these engines handle a lot better.

But these engines are very compact and work on these engines, especially on the cylinder heads can be difficult. So, replacing a spark plug on these engines isn’t the easiest thing to do.

And consequently, they suffer from lubrication issues and other problems that we are going to discuss later on in the article.

Important Subaru Boxer Engines

The important thing is to know that there are a few series of engines that you need to be aware of.

  • EJ – Created in 1989 and still used in some models
  • FB – Replacement for the EJ
  • FA – Development of the FB design
  • EZ – Six Cylinder Boxer

The most famous is the EJ series. These are engines from 1.5L and up to 2.5L in displacement. Easily the most popular Subaru engine ever built. Famous engines are the EJ20, EJ25, EJ253, EJ255, and the EJ257 in the Subaru STi.

Other series of engines are the EZ and FB. EZ engines are six-cylinder engines, while the FB is the replacement for the naturally aspirated EJ engine.

Other famous series include the FA, the FA is the high-performance version of the FB engine with reduced weight and designed for turbocharged applications.

Overall, these are the most common engine codes that you will come across while looking for Subarus.

Subaru Engine Problems

We learned the basics of the Subaru engines and the most common engine models. Now let’s take a look at the common Subaru engine problems and see why Subaru engines fail!

  • Rod Bearing Failure
  • Oil Consumption
  • Head Gasket Failure
  • Oil Leaks

1. Rod Bearing Failure

One of the main problems with Subaru engines is rod bearing failure. Subaru engines simply seize when they fail.

They will spin a bearing and they seize. This is good and bad at the same time. It is good because you can rebuild the engine and it is bad because it will cost you a good penny. But why does this happen?

Well, there are two main factors. One is poor maintenance and the second factor is oil starvation which is common on some EJ engines.

Poor maintenance and rare oil changes will result in your engine failing this way. The bearings on the crankshaft and rods have to be lubricated properly.

These Subaru engines have very tight oil passageways that can easily clog up and make your bearings starve from oil.

In addition to this, there is the situation with oil starvation. The lubrication system of these engines is not extremely good.

So, even if you take care of the engine the best you can, you will still be able to ruin it. Especially if you race it around the track or do something similar that will leave some of the portions of the engine not lubricated.

That’s why you should be aware of rod bearing failures since they are extremely common on Subaru engines and can often occur above 100,000 miles.

Now let’s move on to the next Subaru engine problems.

2. Oil Consumption

The second most common problem on Subaru engines is the high oil consumption. Subaru engines, especially at higher miles can be serious oil burners.

This problem often leads to rod bearing failure because the engine can run low on oil and not be oiling properly.

So, you get the idea of how one problem goes on top of another and the eventual end game is complete engine failure.

This is why we rarely recommend buying a Subaru on the used market. Especially at higher miles, for example, above 150,000. And consequently, this is why used Subarus are so cheap.

They most likely either burn oil or have other engine issues.

3. Head Gasket Failure

Another very common issue on Subaru engines is the head gasket failure. Subaru engines, especially EJ25s want to go through a lot of these gaskets. So, why does it happen?

This problem is attributed to the low-quality gaskets that Subaru was using. And it is very much recommended to upgrade the stock gaskets with new ones.

If your engine overheats, the heads will get tweaked and then you will have to refurbish them. Or if this engine seriously overheated, you might need a whole new long block.

And you definitely don’t want this to happen because it is very expensive to fix.

So, tracking the temperatures and preventing some serious overheating from happening is a good way to save your engine.

4. Oil Leaks Around The Engine

Another major problem that we must add to our Subaru engine problems is the situation with oil leaks.

Subaru engines simply love to leak oil all over the place. Seeing a clean example is a rarity when it comes to Subaru engines.

There are many seals that can leak, such as the front and rear main seals, oil pan gasket, PCV baffle plate, camshaft seals, and spark plug tube seals.

On top of that the valve cover gasket can also leak oil and cause a huge mess.

Let alone the mess when you have oil leaks, another very serious issue is the oil level. If these problems are not fixed, your engine will starve of oil.

When the engine starves of oil, the engine fails completely. So, beware of this unless you want to ruin your engine. Always top off the oil if there are serious leaks.

Subaru Engine Reliability

When it comes to the Subaru engine reliability, this really depends on the engine type since some of these problems do not occur on every Subaru engine.

For example, EZ and early EJ engines like the EJ20 are bulletproof. While others such as the EJ25 and its derivatives are pretty poor in terms of reliability.

FB engines are still new but they still have these common issues here and there. Although, not at the same scale as the EJ25.

So, overall, the EZ engine is the best Subaru engine in terms of reliability. The downside of these engines is that they consume a lot of fuel and they can be expensive to maintain.

When it comes to Subaru engines, getting one as a secondhand vehicle, especially at higher miles is a risk. That’s why you need to have your eyes open and find a good sample.


In this article, we have covered quite a bit when it comes to the Subaru engine problems. First, we learned the basics of the boxer engine and the most common Subaru engine codes.

In the second part, we discussed the common Subaru problems. These include oil consumption, head gasket failure, oil leaks, and rod bearing failure.

Overall, Subarus on the used market is a risky move and you need to find one that is in good condition and well-maintained if you want to see a lot of miles from it.