AT Oil Temp Subaru: The Meaning and Solution

Seeing the “AT oil temp Subaru” shouldn’t make you panic because sometimes it’s an issue you can fix yourself. First, check the transmission fluid level and add more oil if needed; if the problem persists, read the DTC codes to know what’s wrong and figure out how to fix it or contact a professional.

AT Oil Temp Subaru

We have the details of that and more in this guide. Read on to be informed to get that annoying warning light off your dashboard.

How To Fix Overheating Transmission Fluid Issue on a Subaru?

To fix overheating transmission fluid issues on a Subaru, inspect the transmission fluid level and add more oil if necessary. Consider doing it if you last changed the transmission oil a long time ago. You can also read DTC codes to know the source of the issue and rectify it.

When the a/t oil temp light flashes on your Subaru dashboard, it means that the fluid temperature within the transmission system is too high. High oil temperature is a serious warning that you should never ignore. So, you can’t continue to drive with the oil temp warning light on. If the light comes on while driving, pull over immediately in a safe location and allow the vehicle to cool down.

Once it has cooled completely and the temperature warning indicator is turned off, try to drive again and observe what happens. If the problem persists, there’s something wrong with your automatic transmission. Notorious triggers of this problem include low transmission fluid and malfunctioning fluid temperature sensors. You could have pushed your Subaru too hard (hard driving – climbing steep terrains, towing heavy loads, etc.) or used the wrong type of oil.


The a/t oil light may also turn on due to defective wiring within the automatic transmission system or a defective transmission oil pump. To fix the issue and make the light disappear permanently, you must rectify the triggers and do it fast. If you don’t act quickly, you can experience a transmission failure, meaning your vehicle will have trouble shifting into gears and won’t move. So, here’s “how to fix at oil temp Subaru” in detail:

  • Inspect Transmission Fluid Amount

The transmission fluid helps lubricate the moving parts with the transmission. In an automatic transmission, the fluid also offers the hydraulic pressure required to make the internal parts function and, most importantly, cool the transmission. Therefore, when the fluid is low, the bearings and moving metal parts lack sufficient lubrication, increasing friction and overheating.

Inspecting Transmission Fluid Amount

The low fluid amount also implies your vehicle won’t produce enough hydraulic pressure (sometimes, an oil level indicator/oil light may appear on your dash). That results in gear slippage or sluggish acceleration. To fix the problem, remove the transmission fluid dipstick. Wipe it off, return it, and then pull it back out. The transmission fluid levels should be between the full and fill marks.

Add more oil until the correct level is needed. After that, let the engine idle, test drive, and see if the problem disappears. If not, something else is to blame.

  • It’s Time to Change Transmission Oil

When did you last swap the transmission fluid? Subaru recommends changing your fluid every 30K to 60K miles. That’s about 2 to 4 years for someone who drives about 15K miles a year, normal driving. But if you do a lot of hard driving, you may require to change the oil more frequently (every 15K mile).

As you check the oil amount, also examine its condition. If it looks old or burnt, consider changing it, which is a simple fix nearly similar to your normal oil change. If you have changed the fluid recently, ensure you use the correct oil for your vehicle.

Experts often recommend the likes of ATF Dexron III. Using the wrong transmission fluid could also trigger the constant flashing warning light and other severe consequences. Also, you should change the oil filter routinely to ensure your transmission liquid is always clean.

  • Replace the TFT Sensor

The thermometric transmission fluid temperature (TFT) sensor monitors the fluid temperature and sends the readings to the onboard computer. The computer (control module) uses the data to ensure a smooth gear-shifting experience. Unfortunately, if the “at oil temp sensor Subaru” malfunctions, it could send inaccurate input.

Replacing Car TFT Sensor

The transmission may also fail to shift as expected, leading to an overheating problem. Sometimes, a faulty sensor will turn on the check engine light. Other times, the engine may go into leap mode to avert damage to the transmission. The best solution would be to replace the sensor.

  • Check for Bad Wiring within the Transmission

The transmission system comprises many electrical connections. You’ll find an electrical connector between each sensor and the transmission that must always work properly. If some wiring or connection fails, it can cut the communication within the system.

In return, you’ll get a continuously flashing oil temperature indicator. Thus, trace all the wiring to see if something is wrong. Wiring issues with the transmission wiring harness could be anything from an open circuit, damaged insulation, stretched wiring, or faulty connectors to damaged insulation. If it’s something you can repair, do it or contact an expert.

  • Check if You Have a Defective Transmission Oil Pump

The oil pump in the transmission system helps circulate the fluid throughout the transmission. In other words, the pump pressurizes the fluid to supply oil to the torque converter and the hydraulic actuator and to lubricate other parts. If the pump fails, the components won’t get the necessary lubrication, and the transmission will overheat and turn the oil temp light on.

Common symptoms of a bad oil pump include whining noise, transmission slipping, and the oil pressure warning light turning on. In the worst-case scenario, the transmission will fail. Fixing a failed pump problem is a DIY task if you’re an expert.

  • Have the TCM Updated

A slipping transmission is one of the too-high a/t oil temp Subaru symptoms. Although that normally indicates a bigger problem, hydraulic circuit issues, when the transmission begins to slip, the TCM may be the one to blame. Take note that a faulty TCM has caused wired symptoms, including “Subaru 3 warning lights on brakes traction control and at oil temp.”

Car Updated TCM

In 2018, Subaru issued a service bulletin regarding the P0841 trouble code, which may indicate an issue with the TCM. The problem has the most effect on select 2018 Subaru models. You can have your dealer update your TCM. The update enables the transmission solenoid to better deal with contamination and stop issues, like Subaru Outback at oil temp and brake light flashing simultaneously.

  • Read DTC Codes

As mentioned, there are many triggers of the oil temp light flashing. Sometimes finding out what exactly is to blame can cost you a lot of time. A code reader (scan tool) can save you time by diagnosing the problem faster. Reading the diagnostic trouble codes from the transmission control module (TCM) would be best.

The TCM communicates with the various components of the transmission system to ensure seamless gear changing. That means it will most likely throw an error code if something goes wrong. So, connect the scanner to the OBDII port and see if you’ll get any codes.

If you do, reference the codes with your owner’s manual or find the interpretation online. From there, you can figure out how to fix the issue. Take note you may require more than a standard scanner to read codes from the TCM.

  • Call an Expert

As you have realized, diagnosing and fixing an issue with the transmission can be challenging. Besides, the transmission is a delicate component that requires a professional’s keen eye and experienced hand.

Calling Car Expert

So, to avoid causing further damage, especially if you’re unsure what’s wrong, look for a reliable mechanic to help you accurately diagnose and repair the “at oil temp light Subaru Forester” problem. Sometimes changing transmission will be inevitable.

Does the AT Oil Temp Warning Sign Indicate the Need for Snow Chains in Subaru Forester?

The AT Oil Temp warning sign in Subaru Foresters does not directly indicate the need for snow chains. It specifically alerts the driver about potential issues with the transmission’s fluid temperature. Snow chains, on the other hand, provide better traction on snowy and icy roads. To enhance winter driving safety, combining snow chains with appropriate tires is advisable in areas with heavy snowfall. Understanding the subtleties of the subaru forester snow chains explained ensures optimal decision-making in winter driving scenarios.


You now know how to approach your “at oil temp Subaru Impreza” problem after reading our guide above.

Here’s a summary:

  • The automatic transmission oil temperature light flashing on your dash indicates that the liquid transmission temperature is too high.
  • Common triggers include low transmission fluid amount, faulty TFT sensor, malfunctioning transmission liquid pump, bad wiring, and sometimes using bad transmission fluid.
  • To fix the problem, you must address these triggers fast before they worsen the situation leading to issues like the Subaru Outback at oil temp and abs light on simultaneously.
  • You can diagnose the “at oil temp light Subaru Outback” more quickly using an OBDII scan tool and save some valuable time in repair.

Now we leave you to figure out the problem and make the oil temperature indicator disappear. If you need help determining what’s wrong, contact a reliable mechanic.

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