Subaru Legacy Problems: 9 Common Issues (Explained)

The Subaru Legacy is a Japanese all-wheel-drive car known as the flagship vehicle of the company.

Its powerful boxer engine and refined drive are just some of the reasons why the Subaru Legacy remains one of the most celebrated Japanese cars around the globe.

Let’s look into 9 common issues with the Subaru Legacy.

Subaru Surges Forward When Shifted In Park

Your car undergoing unintended acceleration would be the last thing you want as a driver. It is most common when you’re about to park the vehicle.

There are quite a few explanations why your Subaru Legacy may perform unintended accelerations randomly.

It could also be because of malfunctioning sensors in the car. Advanced technology might have many benefits, but there are also some drawbacks.

Here are a few other reasons why this might happen:

  • An ineffective fault detection system may be one of the causes. It might be that the fault detection system in your car is flawed and cannot handle foreseeable unwanted outcomes. Unintended acceleration is a tenable outcome if the system detects it first.
  • There could be a malfunction in the throttle body position sensor.
  • The throttle body assembly could be faulty.
  • The powertrain control module may not be working properly.
  • There may be an issue with the brake override system.

You can take your car to the service station for the inspection of the above-mentioned parts of your car to avoid any cases of unintended acceleration when you’re parking or driving.

Consistent Draining Of Underpowered Batteries

The Legacy batteries aren’t defective; they are just underpowered, especially in the 2015 model. When you shut off the vehicle, the batteries can continue to drain through what is known as a parasite drain.

Many drivers don’t know it’s a battery issue until they restart the car a couple of times.

It mostly happens when the battery is incapable of handling the draw from the vehicle’s electrical systems – especially after it’s been turned off.

If the battery drains every few days, you’d have to either constantly jump into your car or install a couple of trickle chargers by yourself.

Here is why it may happen:

  • There may be an underlying issue with the CAN or controller area network of your Subaru Legacy. A malfunction in this system can affect the sensors, electrical units, microcontrollers, and actuators that communicate with each other.
  • If the vehicle enters a sleep mode when shutting down, there might be a malfunction in the system’s sleep mode.
  • A software error can make the car abruptly enter sleep mode after turning it off.

For these reasons, the system constantly draws power from the battery rather than conserving it.

This parasite drain is the reason why there’s not enough power left in the battery to crank up the engine when the car starts again.

Subaru Windshield Cracking

Unlike a chipped windshield that’s been hit by a rock, many drivers and experts believe that the new acoustic glass feature in the Subaru Legacy is the reason behind the cracking.

The crack starts from a single point of impact and spreads further. It is most common for cracks to develop from the very bottom of the windshield, close to where the wipers are located.

When something hits your windshield, at least you’re able to explain the cracking, but in this case, the cracks appear without an apparent cause.

Here are a few possible explanations for why the windshields crack:

  • The acoustic glass windshield is unmatched when it comes to dampening the sound of the wind, tires, and multiple other distracting noises when you’re trying to concentrate on driving. Even though its soundproofing capabilities are excellent, improper installation or temperature changes can cause the windshield to crack.
  • Sometimes the de-icer adhesives used on the car’s windshield make it more prone to cracking. A simple wound on the windscreen can develop into a much bigger one due to de-icer adhesion issues.
  • Another reason could be the thickness of the glass itself.

Windshield replacements can also interfere with the proper deployment of airbags and reduce the vehicle’s structural integrity to an extent.

Wiper Motor Overheating

Another issue related to the windshields is the wiper motor overheating. It happens due to the interference between the relay joint and the worm wheel.

Because of this, the wiper arms are parked at a position much higher than their slots. Sometimes the wiper may continuously attempt to return to the former position.

It makes the wiper motor overwork and causes it to overheat.

You can get the motor inspected or replaced if necessary. Sometimes applying a bit of lube on all the connecting components prevents the motor from overheating.

Subaru STARLINK Infotainment Malfunction

The STARLINK infotainment system in the Subaru Legacy nevertheless stands up to its title of providing information and entertainment altogether. But there are a few issues here and there.

For instance, it can freeze up and require a total restart by shutting down the car and starting it up again.

Here’s what STARLINK does:

  1. SOS emergency
  2. Roadside assistance
  3. Stolen Vehicle recovery aim
  4. Automatic collision notification
  5. Smartphone integration
  6. Climate control
  7. Navigation
  8. Touchscreen interface

If there’s an internal short on the computer, here’s what could happen:

  • The backup or rear camera freezes during reverse, it can shut down abruptly as well.
  • The audio and radio control can be shut down due to a head unit failure.
  • The display goes blank during the drive.
  • Complete system lockup restarts even after the vehicle is shut down.
  • The radio volume blares randomly during driving.
  • A glitch can cause the favorites to be deleted and you’d have to link to your smartphone or other devices all over again.
  • The touch screen becomes unresponsive.
  • The radio can turn ON and OFF randomly.

Brake Light Switch Defect

The brake lights are an important indicator for your car and other cars behind you on the road.

Sometimes, due to a malfunction, the Subaru Legacy brake lights cease to ignite, leaving room for a lot of mishaps to occur on the road.

According to the manufacturer, the cleaning products used inside the car may be the cause. These products can gunk up the electrical contacts of the switch.

Sometimes the cleaning products create a sort of silicon goop layer that messes up the conductivity, preventing the brake lights from turning ON when pressing the pedal.

This increases the risk of a rear-end collision. But sometimes ineffective brake lights create problems that go far beyond the exterior.

These include,

  • Many specific ignition and transmission functions get disabled until the brake light is recovered.
  • Switch button ignition interlocks make it impossible to start the engine due to malfunctioning brake lights.
  • The transmission lock ceases the function of shifting out of parking because of this malfunction.
  • The vehicle stability control warning light gets disabled.
  • The eyesight operation shuts down.

If you’re having issues starting the car or shifting it into neutral, you can try pressing the brake pedal to recover the gear.

If all else fails, try replacing the brake light with a new one. It usually fixes the issue.

Subaru Low-Density Impellers Inside Fuel Pumps

Although the Denso fuel pumps are not found in newer vehicles because they were recalled, some vehicles had fuel pumps that limited the amount of gas reaching the engine.

Which made it harder to crank the engine every time.

The impellers would absorb fuel but they would highly deform, which would interfere with the flow.

It would turn the engine rough over time and cause it to stall when driving at high speeds. Subaru uses two impellers; one is a low-pressure pump and the other is a high-pressure pump.

The lower one uses a rotating disk known as the impeller that draws fuel but former impellers couldn’t rotate. Fortunately, there was a fuel pump recall by Subaru Legacy in 2020.

But many used cars manufactured from April to July 2018 may still possess the same fuel pump system, so if you come across one, get it replaced to protect your engine.

Subaru Oxygen Sensors Malfunction

Oxygen sensors play a major role in helping the engine stay effective and reliable.

Without an effective oxygen sensor, the Subaru Legacy would experience a number of problems including misfires, poor fuel efficiency, and limited acceleration.

Oxygen sensor repairs don’t cost as much as the incoming repairs with a faulty oxygen sensor like engine-damaging misfires. If the check engine light is illuminating on the dashboard, there may be a problem with your oxygen sensor.

Here‘s why these sensors might malfunction:

  • High mileage
  • Internal contaminant poisoning
  • Electrical issue

Oxygen sensors aren’t that costly to get replaced and it could happen to any car. A single or two-wire unheated oxygen sensor must always be inspected.

They can also be caused by some byproducts of combustion like fuel additives.

Head Gasket Failures

Head gasket failures in a Subaru Legacy are mostly due to the coolant becoming highly pressurized, which causes the head gasket to burst.

Other reasons include,

  • An overheating engine can expose the gasket to such a high temperature that its exterior cannot handle and cause it to burst or fail.
  • Pre-Ignition or detonation can also make a head gasket fail. That is because the ignition process either develops too slowly or begins before the spark plug fires. Poor fuel distribution inside the cylinder or cooling system failures can trigger this.
  • If you apply the wrong gasket in the slot, it can result in a failure.
  • Some errors in the installation process can also serve as a foundation for this issue.

You can take your Legacy to a mechanic and get the engine inspected for oil or coolant issues.

A head gasket replacement is very cheap and necessary to avoid further complications.

Power Steering System Issues In The Subaru Legacy

Most models of the Subaru have power steering as a standard feature, which many drivers prefer to make the drive easier for them.

However, a few complaints were reported that the power steering pulls the vehicle to one side, especially at highway speeds, which can cause a lot of accidents in traffic.

This problem can occur for the following reasons:

  • Contamination due to moisture getting through to the power steering system.
  • The belt connected to the crankshaft of the engine is snapped.
  • Low fluid in the system.
  • A leak in the hose lets all the hydraulic fluid out.
  • A worn pump or seals within the power steering system of the Subaru Legacy vehicle.

General Pros And Cons Of The Subaru Legacy


  • The slender roof pillars in both front and rear make the Subaru Legacy windshield view very impressive.
  • The EyeSight driver assistance system ensures the driver’s safety on the road.
  • The steering system has a very smooth and effortless feel due to the excellent weighing out of the steering wheel.
  • Although the cargo space is around 15 cubic feet, the design is spacious, making it accessible for passengers to store their things.
  • The Subaru Legacy has an excellent safety rating, ensuring its reliability.
  • Legacy is known for its outstanding fuel economy.
  • The standard boxer engine sits lower in the engine bay than most engines, which effectively balances out the engine’s weight.
  • The well-designed automatic CVT has seamless performance.
  • The standard symmetrical AWD system in almost every new model of Subaru Legacy provides you with extra peace of mind while driving in bad weather.


  • Unintended acceleration
  • Consistent draining of batteries
  • Wiper motor malfunctions
  • Infotainment problems
  • Rear light issue
  • Head gasket failures

What Do The Reviews Say?

The Subaru Legacy is an extremely comfortable vehicle to drive.

With its decent and classy exterior and customized accessibility, there isn’t more one can ask for in a Japanese sports car.

“The exterior is well designed. The first time I drove it, I felt like I had been driving it for years. Like the 11.5-inch info screen. Like having an iPad on your dashboard.”

Source: (

The safety features of Legacy are futuristic and deserve the highest safety rating by a margin.

The pricing stands up to the value delivered by Subaru.

“ The car is stylish, adequately quick, has an amazing ride and all the modern features (you can ride for miles with no hands and feet if you care to, as with a lot of newer vehicles).”

Source: (

Year Mileage Prices
2018 26.02 Mpg $21,934
2019 25.87 Mpg $22,435
2020 27.35 Mpg $22,745
2021 27.00 Mpg $22,895

Go Back: Problems per Subaru Model.

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ⓘ  The information in this article is based on data from National Highway Traffic Safety Administration (NHTSA) recall reports, consumer complaints submitted to the NHTSA, reliability ratings from J.D. Power, auto review and rating sites such as Edmunds, specialist forums, etc. We analyzed this data to provide insights into the best and worst years for these vehicle models.