Most Common Subaru Transmission Problems

Vehicle:   Subaru
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Subaru vehicles are generally very reliable and are known to last over 200,000 with just regular maintenance. In a few cases, Subaru owner's many notice automatic transmission problems that need to be repaired by an auto mechanic. In this article, we go over those common problems and causes that are known to affect Subaru transmissions. 

Slipping or shuddering on take-off

Torque Converter CLutch

Subaru cars that use a conventional 4-speed automatic transmission, designated as 4EAT, suffer from one very common issue. It will show up through several symptoms, ranging from slipping, shaking, or shuddering when accelerating from a standstill.

In some cases, there might also be a noticeable slippage in higher gears. Generally, there will be no warning lights or symptoms other than the check engine light. 

Possible causes and solutions

  • Transmission stuck in 4-wheel drive mode in situations it should be in 2-wheel mode. It is easy to test this by installing a fuse into the front-wheel-drive switch located under the hood. If this does not eliminate the problem, the cause might be with input sensors or TCU itself.
  • Faulty or sticking Torque Converter Clutch solenoids, causing slipping or shudder at higher speeds. These solenoids are sensitive to temperature and tend to work fine until they warm up. Although Subaru does not sell the solenoid separately, there are aftermarket solenoids available.

Transmission temperature warning

Subaru cars with a conventional 4EAT 4-speed automatic transmission can sometimes suffer from what it appears to be an overheating transmission. In most cases, the ‘transmission temperature’ warning light will start flashing. This can happen while driving, or even after the car is started.

Possible causes and solutions

  • Clogged oil cooler or connecting hoses, which prevent the circulation and cooling of transmission fluid. The easiest way to check this is to look if there is transmission fluid inside the return line.
  • Faulty pressure control solenoid, resulting in loss of transmission fluid pressure. As a result, the flow through the oil cooler will be too slow and result in overheating. In addition, this can also cause shift issues such as harsh or delayed gear changes.

Stalling when coming to a stop

Newer Subarus with a Continuously Variable Transmission called Lineartronic can have a problem that leads to engine stalling when coming to a stop. In most cases, this will only happen in situations when there is sharp braking after a long drive. After stalling, the car will start and run without any problems.

Possible causes and solutions

  • Faulty torque converter, with clutch staying engaged when it should disengage. The resulting lockup causes the engine to stall. The cause of this problem is a worn thrust washer inside the converter that blocks the clutch release. Replacing it with a Torrington bearing solves the issue.
  • Incorrect transmission fluid. Make sure that only Subaru’s approved CVT fluid is used.

Growling noise during acceleration

Newer Subarus that have a Continuously Variable Transmission called Lineartronic can develop an issue that shows up as intermittent or constant growling noise coming from the transmission. Usually, this happens only during accelerations, with no other symptoms or warning lights present.

Possible causes and solutions:

  • Failure of primary or secondary pulley bearing, which is a fairly common issue that affects all versions of Lineartronic transmissions. To track down the source of the problem, drive the vehicle at the speed where the noise is the loudest and then shift into a lower ratio. If the noise changes its tone and pitch, the fault is with primary pulley bearing. If there is no change, the secondary pulley bearing is a probable fault. Although Subaru does not sell these bearings separately, there are aftermarket kits available.

Engine speed variations

Newer Subarus that use Lineartronic (CVT) transmission have one very common issue, which will manifest itself as variations in engine RPM’s when traveling at highway speeds. When this is happening, the engine speed will jump up and down with no input from the driver. This issue affects both TR690 and TR580 transmissions and will trigger a check engine light, so there will be a corresponding code stored.

Possible causes and solutions:

  • Faulty TCC solenoid, which cuts off when the transmission reaches running temperatures. Testing involves checking the resistance, which should be 12 ohms at ambient temperature and at around 200° F. If the solenoid is bad, the circuit will be open when it warms up. Subaru doesn’t sell solenoids as spare parts, but there are aftermarket ones. However, replacing them involves soldering. 
  • Damaged connectors or wiring between the solenoid and TCU.

 

Based on our experience and research you are more likely to experience transmission problems if you own a Subaru with CVT transmission than a four or five-speed automatic transmission. 

While these are some of the most common Subaru automatic transmission problems, it does not mean that all Subaru vehicles will suffer transmission problems. 

 

By YOUCANIC Automotive Experts
Jul 2020