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Subaru WRX engine: is it reliable?


Subaru’s roaring signature WRX flat-four engine has been cruising American roads for nearly two decades. What has changed over the years?

Subaru Impreza WRX EJ25 boxer engine 2011 - Subaru Photo

The Subaru WRX and its engine are legendary parts of everyday driving as much as they are an iconic part of motorsports. You can’t get into any aspect of rally racing without talking about the legendary Subaru WRX. Plus, you’d be hard-pressed to make an appearance at any type of gathering or car club and not come across a WRX.

While its world rally championship-winning heritage and world-class all-wheel drive system are definitely talking points, one thing stands out even to those unfamiliar with the WRX’s rally heritage: the engine’s deep, furious roar. Subaru flat-four boxer. It is instantly recognizable and familiar to most car enthusiasts.

Like a Porsche engine, the WRX (and most other Subarus) uses a flat-plane engine design, meaning the pistons run side-to-side instead of up and down.

The WRX and Subaru were dominant force in rallying in the 1990s and early 2000s. With driver Colin Mcrae Leading the Subaru World Rally Team and racking up championship victories, demand for the street version of the turbocharged all-wheel drive warrior continued to grow.

Although the Subaru WRX has previously existed for other markets, the United States only got the road rally car in 2002. However, despite its controversial front design, the WRX was an instant hit in the United States.

Since its debut, the WRX and its distinctive boxer engine sound have grown in popularity. Let’s take a look at the different generations of WRX and the engine specifications available.

Subaru WRX Generations and Engines: US Launch

Subaru Impreza 2002 - Photo by OSX/Wikipedia Commons

Second generation Subaru WRX (2002-2003)

The first version of the WRX available here in the United States came with the 2002 model year Subaru Impreza. This is the second generation Subaru Impreza and the first generation design three. It is known as the “bug eye” because of its round headlights.

The bug-eye WRX is powered by a 2.0-liter turbocharged flat-four engine, known internally as the EJ20. The EJ20 in the bug-eye produces 227 horsepower and 217 lb-ft. of torque Although not the most efficient, the bug-eye WRX has EPA ratings of 18 mpg in the city and 25 mpg on the highway.

2004 Subaru WRX STI - Picture of Subaru

Subaru WRX Facelift 2nd generation (2004-2005)

The first major change to the Subaru WRX variants delivered in the US came with the facelift of the 2004 Subaru Impreza. While the front-end redesign is substantial, the biggest change here is the addition of the STI model to the WRX.

The STI is the more track and/or race-focused version of the WRX. The STI has a more aggressive suspension, more power, and a six-speed manual transmission instead of a five-speed.


This facelift is known as the “blob-eye” WRX and keeps the EJ20 with the same power output at 227 horsepower and 217 pound-feet. of torque, just like the bug-eye. It also sees fuel economy ratings of up to 20 mpg city and 27 mpg highway.

The STI, however, has gained significant power. That comes courtesy of a displacement bump to 2.5 liters. This larger variant of the same boxer engine is known as the EJ25. The EJ25 in the 2004 WRX STI makes 300 horsepower and 300 pound-feet. of torque Of course, the extra power comes at the expense of fuel economy, with the STI achieving up to 18 mpg in the city and 24 mpg on the highway.

It’s not the last stop for this generation of WRX either.

2006 Subaru WRX - Photo by IFCAR/Wikipedia Commons

Second generation Subaru WRX Facelift (2006)

The second generation received a facelift with the 2006 model year Subaru Impreza. This change again brought a new nickname: “Hawkeye.”

For the Hawkeye, the WRX and WRX STI are still available. However, the WRX got an update and would now come standard with a slightly watered-down version of the EJ25 found in the drop-eye STI. Additionally, the STI is also equipped with an EJ25.

The EJ25 engine is rated at 230 horsepower, giving it just a three-horsepower advantage over the previous EJ20. However, torque sees a significant increase to 235 lb-ft. Still equipped with a five-speed manual transmission, this generation of WRX boasts fuel economy ratings of up to 20 mpg city and 26 mpg highway.

The STI also retains power from the previous facelift at 300 horsepower and 300 pound-feet. of torque Additionally, fuel economy ratings remain the same at 18 mpg city and 24 mpg highway.

2012 Subaru WRX - Picture of Subaru

Third-generation Subaru WRX (2007-2014)

The third-generation WRX finally arrived with the 2007 model year Subaru Impreza. Designed to be more conventional and user-friendly, the WRX became a bit larger and lost some of its handling feels in lieu of a more comfortable everyday suspension.

The third-generation WRX retains the EJ25 from the previous generation. In 2007 and 2008 models, the WRX had 224 horsepower and 226 lb-ft. of torque However, the 2009 Subaru WRX got a refined version of the EJ25 that bumps power figures up to 265 horsepower and 244 pound-feet. of torque, This new power output has had an impact on the economy, as it now has ratings of 18 mpg city and 25 mpg highway.

The third-generation WRX STI and its version of the EJ25 also saw their output increase to 305 horsepower.

Unfortunately, the torque was reduced to 290 lb-ft. Fuel economy ratings for the third-generation STI rise to 18 mpg city and 25 mpg highway.

With the end of the third generation of the WRX, the legendary rally-inspired care associated with the legendary EJ engine also came to an end.

Subaru Photo: Travis Pastrana Rallye WRX STI

Subaru WRX 4th generation (2015-present)

As with the last generation, the WRX adopted more mundane standards with the 2015 model year. However, the WRX and WRX STI became their own model, dropping the Impreza name. Although they share the platform with the standard Impreza, the WRX and WRX STI have much more aggressive styling.

However, the biggest change for the fourth-generation models, as we mentioned above, is the conspicuous absence of an EJ engine under the hood. That being said, the familiar four-plane boxer brief design remains the same.

Instead of an EJ, the FA20 engine took over from the WRX family. This is the same engine frame found in the Toyota 86, Subaru BRZ, and Scion FR-S. However, these models are not turbocharged.

The fourth-generation WRX and its FA20 come standard with 268 horsepower and 258 lb-ft. of torque It has an EPA fuel economy rating of 20 mpg city and 27 mpg highway.

The fourth-generation WRX STI develops 305 horsepower and 290 lb.-ft. of torque It gets an EPA-estimated 17 mpg in the city and 23 mpg on the highway.

Subaru WRX Engine Reliability

Is a Subaru WRX engine reliable? Unfortunately, the truthful and straightforward answer is; not really.

The EJ20s found in earlier WRX examples are the least problematic of the previous two generations of WRXs delivered in the US. However, they are still subject to rod bearing and head gasket failures. Especially with high mileage, it is important to keep the oil clean at an adequate level. However, the most important thing is not to stress the engine too much.

While it’s awesome to see WRXs flying around a rally stage, it’s important to remember that they have a trailer full of parts and big budgets to avoid any accidents. If you turn off your daily driver’s engine, it’s unlikely you’ll restart it at the same time they do.


The EJ25 is the most problematic WRX engine of all. Unfortunately, they are so unreliable and prone to premature failure that WRX and WRX STI owners have filed a class action lawsuit against Subaru. The lawsuit alleges that the EJ25 has defective connecting rods and crankshaft bearings that could fail long before the engine’s reasonably expected useful life. This lawsuit explicitly cites the 2009-2014 WRX and WRX STI models.

However, earlier EJ25 variants are prone to similar failures with ring failures landing on the pistons. Each of these failures can result in thousands of dollars in repairs and may even require a complete engine replacement. The lawsuit was settled with Subaru agreeing to pay owners who had to pay for repairs, as well as extending warranties on affected vehicles to a period of eight years and 100,000 miles.

2010 Subaru Impreza WRX - Picture of Subaru

Engine reliability issues

Unfortunately, the latest generation of WRX and WRX STI equipped with the FA20 boxer engine is not in a much better position. Currently, owners give them an average reliability rating of just two out of five.

Like the EJ series engines, the FA20 engines in the fourth-generation WRX and WRX STI models experience connecting rod failures. But most of these failures are due to modifications such as replacement tunes and additional power.

While it’s not a huge concern when driving a standard WRX or WRX STI, many buyers interested in these cars like them for their ability to be modified quite easily. So, it’s something to keep in mind if you’re buying a WRX or WRX STI to add power or race.

Another issue some owners report with FA20-equipped models is poorly mapped factory tunes. They claim that the tunes are too aggressive and run too lean, meaning there is not enough fuel for the amount of air entering the engine. This can cause detonation problems leading to connecting rod failure.

As with any car, owners can avoid many problems associated with the FA20 engine by driving it sensibly. But, when the car is inspired by real rally cars, it’s a little hard to help but want to open it up and see what it can do.

2021 Subaru STI and WRX - Picture of Subaru

Should you buy a WRX?

Despite the well-documented problems associated with Subaru WRX engines of all generations, they still have a cult following that drives them every day. As with any car, proper maintenance, and sensible driving go a long way toward keeping a WRX alive.

That’s why when purchasing a used car, we strongly recommend that you run a vehicle’s VIN through our free VIN lookup tool to get its complete and detailed history.

Additionally, finding a well-maintained car with repair and maintenance records is imperative when purchasing a car like this if you plan to use it every day. No one wants to hear that a car they’re interested in isn’t reliable, but it’s important to know what you’re getting into before you buy it.

Despite its problems, the Subaru WRX is a fantastic car experience to drive. However, owners and potential buyers should keep in mind that they require a little more maintenance than your average economy car.

Photos: Subaru, Wikipedia Commons: OSX; IFCAR


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