Why is the Oil Temperature Light Flashing on my Subaru?
Your Subaru dashboard has several warning lights that alert you when something is wrong with your vehicle. If you’ve never seen your Subaru AT Oil Temperature Light flashing, it may come as a surprise. This warning light is a serious warning and should never be ignored.
In this guide, we’ll explain the basics of a Subaru AT flashing oil temperature light and show you what causes it. We will also show you some ways to fix this fault in your Subaru and give you answers to the most important questions:
What does the flashing oil temperature warning light on a Subaru AT mean? The AT oil temperature light is used for the oil temperature system in the automatic transmission. The flashing light means that the automatic transmission oil is getting too hot compared to the manufacturer’s specifications. The light is flashing because it is a serious problem that cannot be ignored.
In addition to the light, you will notice a few symptoms. Most importantly, your transmission is not functioning properly. Once the light starts flashing, it is important to stop and allow the transmission to cool before permanent damage occurs.
What Causes the Subaru AT Oil Temperature Light to Come On?If the AT Oil Temperature light is on on your Subaru dashboard, it could be that your Subaru is overstrained. It could also be that the transmission oil is too low, the wrong type of oil, or that the transmission oil temperature sensor is faulty. Other possibilities include faulty wiring, transmission slippage, or a faulty transmission oil pump.
Any of these causes are serious and should be addressed before proceeding.
1. Transmission Overheating (Harsh Driving)
Subarus are designed for extreme adventures. However, there is always the possibility that you are overtaxing your vehicle.
If you are pulling heavy loads, climbing steep hills, or racing down trails, you may be overtaxing your transmission. The good news is that if you stop quickly and let the transmission cool, you may not need to repair it.
2. Low Transmission Fluid Level
Driving your Subaru with a low transmission fluid level can have serious consequences for your vehicle. First, the transmission overheats due to lack of lubrication.
Under normal driving conditions, the oil level in your Subaru should never drop. If this is the case, you can assume that there is a leak somewhere in the system. To prevent this problem from recurring, you will need to not only refill the transmission, but also repair the leak that is causing the fluid level to drop.
3. Using the wrong transmission oil
There are many different types of transmission oil. It is important to put the right oil in your car; not doing so can cause problems.
For most vehicles, Subaru recommends using Subaru ATF HP or Dexron III in your transmission. Using the wrong oil for your vehicle can have serious consequences and can even damage your transmission. It can also cause your automatic transmission oil temperature to start flashing.
4. Transmission Oil Temperature Sensor Failure
When the sensor that measures oil temperature fails, the readings will be inaccurate. The first sign will be a flashing light, indicating that there is some problem with the system.
You may also notice that your transmission won’t shift as it normally would because it’s not adjusted properly. In severe cases, your car may go into limp mode to protect the transmission.
5. Faulty wiring
Although the gearbox is a mechanical component, it is made up of many electrical connections. There is an electrical connection between each sensor and the transmission that must be in perfect condition to communicate. If any part of the wiring or connector fails or breaks, the communication can be interrupted. Instead, the AT oil temperature light will flash.
6. Gear Slipping
Transmission slippage is usually a sign of a bigger problem. A defective clutch pack can cause the transmission to slip.
There could also be a problem with the hydraulic circuit. In addition, all the problems already mentioned can also lead to transmission slippage. Whatever the cause, when your transmission starts to slip, the oil gets hot and this warning light may flash.
7. Transmission Oil Pump Failure
The transmission oil pump is responsible for circulating fluid through the transmission. If it fails, the transmission doesn’t get the lubrication it needs and it will overheat. You may hear a whining noise or experience slippage. If the pump fails completely, you may not be able to put it into gear.
How to Fix the Oil Temperature Warning Light on a Subaru AT
When the oil temperature warning light on your AT starts flashing on your dashboard, you need to act quickly to fix the problem. Ignoring this can lead to a complete failure of the transmission. As professional mechanics, we will go through these steps. However, we always recommend reading the service manual for model-specific information.
1. Check the Transmission Oil Level
Before doing anything else, make sure there is enough fluid in the transmission. Warm up the engine first and be sure to park on a level surface.
Remove the transmission dipstick and wipe it clean. Reinsert it into the system and pull it out again. Make sure the fluid level is between the “Fill” and “Full” marks.
2. Changing and Flush Transmission Oil
If your transmission fluid is burnt or old, you should consider changing or flushing it. Changing transmission fluid is similar to an oil change. On average, Subaru recommends changing your transmission fluid every 30,000 to 60,000 miles. However, if you push your vehicle to the limits, you may need to do this more frequently.
3. Read Error Codes from the Transmission Control Unit
The transmission control unit is responsible for communicating with the engine to ensure a smooth ride. However, if the module detects that there is some issue with the system, it will issue an error code. Once you have the information from the module, compare it to our online error code library to find out what’s wrong.
4. Check the sensors and wiring
The next step is to check the sensors and wiring. There is always the possibility of a broken or faulty wire. Trace all wiring and check connections as well.
5. TCM Update
Subaru has issued a service bulletin explaining that trouble code P0841 may indicate a problem with the transmission control module. This issue seems to be most prevalent in certain 2018 model year Subaru vehicles.
To fix it, your dealer will update the TCM with new logic. This update will allow the solenoid valve to better filter out contaminants, and the warning should no longer occur.
6. Consult an Expert
It’s not always easy to diagnose and fix transmission problems. Since the gearbox is a critical part, we recommend that you only work on this part if you have the appropriate experience.
You don’t want to do any major damage, so you might be better off paying a mechanic instead. If you’re not sure what’s going on, ask for a second opinion to be safe.
Why is the AT oil temperature indicator flashing on my Subaru? Your transmission may be overheating due to excessive use. Additionally, the transmission oil temperature sensor may be bad, the wiring may be faulty, the transmission may be slipping, or the oil pump may have failed.
How long can you drive with the oil temperature light on? If the oil temperature light is on, you should never continue driving. It is important to stop in a safe place immediately. Allow your transmission to cool completely before driving again. If that doesn’t fix the problem, find out what’s wrong and fix it.
What causes a transmission to overheat? Sometimes it’s just because it’s been working too hard. Other times it could be that the fluid level is low or contaminated. Mechanical failures can also occur if the wiring, fluid temperature sensor, or oil pump are defective. In addition, gearbox slippage can lead to overheating.
How can I cool the gearbox?It is best to drive to a safe place and turn off the engine. You can open the hood and wait until the transmission cools down. This can take 30 minutes or more, depending on the transmission temperature and the outside air temperature.