Subaru AT Oil Temp Light Flashing: Meaning, Causes, and Fix!

The transmission oil or fluid in your Subaru AT keeps the transmission components performing efficiently. But sometimes, the oil level or condition isn’t ideal and the AT Oil Temp light starts flashing. In that case, you must find out the reasons and fix it immediately. 

Hence, the question arises: why is the Subaru AT Oil Temp light flashing? Low transmission fluid levels, transmission leaks, fluid degradation, etc., can cause the AT Oil Temp light to flash. You need to check the transmission fluid level and top it off. 

Besides, other fixes can save you from an expensive transmission rebuild. I will elaborate on every relevant topic below. Let’s get started.

Subaru AT Oil Temp Light Flashing: What Does It Mean?

AT stands for Automatic Transmission and oil temp means Oil Temperature. As you might already know, the automatic transmission system in your Subaru needs transmission oil to operate properly.

It is also known as transmission fluid. The transmission oil keeps the transmission components cool by reducing friction. At the same time, the transmission oil prevents wear on the components.

When the transmission fluid level is low or the oil quality is bad, the oil loses its cooling and lubricating efficiency. As a result, metal gears inside the transmission face increased friction and generate a lot of heat. So, the transmission oil temperature starts to rise.

If the transmission oil temperature exceeds 200 degrees Fahrenheit, the AT Oil Temp light on the dashboard starts flashing. In layman’s terms, this flashing light means your transmission oil temperature is too hot.

What Causes Subaru AT Oil Temp Light Flashing?

When the AT Oil Temp light in your Subaru is flashing, there can be multiple underlying reasons. Let me explain them one after another.

1. The Transmission Fluid Level Is Low

If the transmission fluid level in your Subaru is lower than normal, the transmission components will face higher friction. So, they will start generating a lot of heat. The transmission oil temperature will go up and trigger the AT Oil Temp light.

Accordingly, there can be leaks in the transmission oil line, which causes the oil level to drop noticeably. Thus, oil deterioration can also reduce the active amount of oil in the transmission system.

2. Not Using the Recommended Transmission Fluid

Each vehicle needs a specific type of transmission fluid recommended by the manufacturer. Subaru suggests using the Dexron IIii in your vehicle to keep the transmission system working properly. If you use any other transmission fluids, the transmission system might not run smoothly.

As a result, there will be increased friction between transmission components. The excessive heat generated by the friction will cause the AT Oil Temp warning light to flash.

3. Mechanical Problems with the Transmission System

Transmission components can go bad even if it is not related to the oil level or oil quality. Especially if you have an old Subaru, the transmission components might be at the end of their service life.

During this period, the transmission components may often be faulty. Solenoids, clutch packs, and other components in the system may be bad. These faulty components can be responsible for increasing the transmission oil temperature. As a result, the AT Oil Temp light will flash on the dashboard.

What Happens After Subaru AT Oil Temp Light Flashing?

If you don’t take prompt action after the AT Oil Temp light is flashing, there might be grave consequences around the corner. Here is a quick overview.

• The Car’s Performance Is Reduced: The transmission system transfers the power from the engine to the wheels. If the oil temperature is too high, it will lose its lubricating efficiency. 

As a result, there will be increased friction between the transmission components. This decreases the power delivered to the wheels.

• Transmission Components Will Wear Faster: Transmission components will face increased friction with extremely hot oils. It results in a faster wear of gear transmission. The debris from the metal components will also deteriorate the oil life faster.
• You Will Require a Transmission Rebuild: If this situation goes unchecked for a long time, transmission components can face severe damage. At one point, the transmission system will seize. So, you won’t be able to drive the car until you rebuild or replace the transmission.

What Are the Symptoms When the Transmission Fluid Is Too Hot?

Besides the flashing AT Oil Temp light, you will observe other symptoms when the transmission fluid temperature is too hot. Here is a quick list.

• There will be trouble shifting gears. The shifts will be harder than before, especially when you shift to the Drive gear
• When you change the gear, there can be a thumping feel
• The gear shifting won’t be smooth or accurate. Often, you might notice gears slipping
• The car will lose power and the acceleration will be sluggish
• You may hear a grinding noise from the transmission system

How Can You Fix the Flashing AT Oil Temp Light on Subaru?

You need to follow a multi-step process to fix this problem. I will guide you through the detailed steps. Read them attentively.

Step 1: Checking the Transmission Oil Level

1. Check the transmission fluid level. To do this, turn the engine on and let it idle until it reaches the operating temperature. 
2. Keep the vehicle in the Parked position. Change gears in each position and see how the system responds. Don’t rev the engine at this point.
3. Shift the gear back to Park and pop the hood. You will see the transmission oil dipstick handle at the furthest position from the front.
4. Pull the dipstick out and wipe it clean using a rag. 
5. Then, insert the dipstick into the transmission fluid reservoir again. 
6. After a moment, take it out and check the oil level. The oil mark should be between the HIGH and LOW position on the dipstick. 

Step 2: Checking the Transmission Oil Quality

• Besides checking the fluid level, you need to check the oil quality as well. If the fluid quality is good, you can refill the fluid without flushing the old fluid. But if the fluid is bad, you need to flush it first.
• After pulling the dipstick out, check the color of the transmission fluid. If it is light red and almost transparent, the fluid is fresh. 
• If the color is light brown, the fluid may not be fresh, but it is still good. You don’t need to flush it. 
• When the fluid is dark brown and has no transparency, it is time to flush it. 

Step 3: Flushing the Transmission Fluid 

1. To flush it, turn the engine on and let it idle for some time. It will heat up the oil and make it easier to drain.
2. Then, place a container below the drain hole. Open the drain nut and let the oil drain completely. 
3. Close the drain nut.
4. Pour flushing chemicals into the reservoir and let the engine run for some time. It will clean the system. 
5. Then, drain the chemical too.
6. Finally, use fresh transmission fluid, as suggested by Subaru. 
7. After running the engine for a while, check the fluid level using the dipstick.

Step 4: Get the Transmission Fluid Line Checked

• If the oil level still drops or the oil gets too hot, there may be other problems with the transmission system. You should take the vehicle to a repair shop and get the transmission system checked for leaks or damages.

FAQs

Here are answers to some commonly asked questions that might enlighten you more. Check them out.

Final Words

A flashing AT Oil Temp light can be a nightmare for Subaru owners. It indicates the transmission oil temperature has crossed the standard limit. When this happens, you are at the risk of damaging the transmission. So, you should act quickly and take a series of steps to save the transmission.

In the Subaru AT Oil Temp Light Flashing: Meaning, Causes, and Fix guide, I explained the impacts of this warning and showed how you can solve the issue. Try these solutions before it is too late.