AT Oil Temp: Meaning, Causes, and Repair Guide

Transmission failures can be one of the most frustrating experiences for car owners. 

The breakdown can be caused by a variety of factors, such as overheating, low fluid level, etc… However, your vehicle will give you warning indications that your transmission is likely to fail. The most evident indicator is that your AT Oil Temp light will be illuminated. 

In this post, you’ll learn about the meaning, causes and repair guide of AT Oil Temp. 

Read on to learn more!

What Does AT Oil Temp Mean

AT oil temp is an abbreviation for Automatic Transmission Oil Temperature. It means to display a warning light if the system isn’t working properly. This warning light on your dashboard provides information regarding the temperature of your transmission fluid. When the temperature rises over usual, this warning light illuminates, alerting you to the overheating transmission. 

The ideal temperature range for transmission fluid is between 175 to 220℉. If the temperature rises above this level, the engine may develop various severe faults and eventually fail. As you continue to drive, the temperature of your vehicle will keep rising. For every 20℉  increase in fluid temperature will shorten the life of your transmission. The alert is triggered because your transmission and engine can not withstand so much heat. 

What Causes AT Oil Temp Light Comes On

The  two most common causes of AT Oil Temp coming on are low transmission fluid and the use of the wrong fluid. As a matter of fact, you need to detect these transmission faults as soon as possible in order to avoid future issues.

Read more: Low Oil Pressure At Idle: Causes & Repair Guide

Low Transmission Fluid

Check the transmission fluid level on the dipstick.
If it is below the MIN mark, you need to top off transmission fluid. The low fluid level can lead to severe damage to the system. Keeping transmission fluid at the proper level helps your car avoid from issues related to AT oil Temp light and remain in top conditions.

Low transmission fluid is one of the most common reasons why the AT oil Temp light comes on. 

The temperature of the vehicle’s transmission system can rise due to a lack of fluid. As I mentioned earlier, when this happens, the “AT Oil Temp” warning light illuminates to alert you of the issue. Once you notice that your transmission oil level is low, check for the leak. If there is no leakage, refill it to the full mark. 

Transmission oil deficiency can cause harm to internal components, necessitating costly repairs. Even if the AT oil temp warning light is not illuminated, it is vital to check the transmission fluid level on a regular basis. You can hire a professional mechanic if you are unfamiliar with checking or changing transmission fluid. It is far less expensive to top off the transmission oil than it is to pay for repairs.

This video shows you how to check and add transmission fluid

Using The Wrong Transmission Fluid

Aside from low transmission fluid, using the wrong transmission oil might cause your AT Oil Temp Light to illuminate. The negative impact of the incorrect fluid on the transmission causes poor lubrication which leads to overheating. If this is the situation, you must remove it as soon as possible to avoid further damage to your gearbox. You can check your owner’s manual for the appropriate transmission fluid for your vehicle.

To get rid of the old fluid remaining in the system, you’ll have to drain and replace it with a fresh one. For your safety, allow the car to cool down first before changing the fluid. It might be easier to send your car to a mechanic for this fix. He can also determine whether you require a drain and fill or a transmission flush. This may help to resolve the fault and improve the performance of your transmission.

This video shows you how to drain and flush the wrong transmission fluid.

What To Do When AT Oil Temp Light Comes On

Once your AT Oil Temp indicator illuminates, the first thing you should do is pull over your car to a safe location and switch it off . Doing so allows your transmission to cool or idle until the light turns off. You can drive after the light goes off. However, if the light comes on again, you’ll need a professional technician to diagnose the transmission problem.

Another thing you can do yourself is to check the transmission fluid level to see whether it is low. If it’s below the full mark, add more transmission fluid until it reaches the right level. Make sure to pour it gradually and carefully. This is because adding too much transmission fluid can cause severe transmission problems. 

Furthermore, if your AT Oil Temp Light flashes when you start your engine, it indicates that there is a problem with your AT control system. When this occurs, you may need to contact your mechanic to resolve the issue. 

Read more: All You Need To Know About Differential Fluid Change


1/ Is it safe to drive while the AT oil temp light is on?

Driving while your transmission is overheated is not safe. When your AT Oil Temp Light comes on, the best thing is to stop the vehicle as soon as you can. 

This indicates that the fluid temperature has risen to at least 250 ℉. A further rise in temperature can be fatal to the engine’s gearbox. Heat is the number one killer of automatic transmissions, so be alert if this light appears on your dashboard. If you continue to drive for a longer period when your AT oil temp light is illuminated, your engine may fail, resulting in an accident. Stop your car immediately if you can or have it towed to the nearest mechanic shop. 

2/ How long can you drive with the AT oil light on?

While you can drive safely to your next destination, you should get your transmission system inspected as soon as possible to avoid further problems. If you drive for an extended period of time with an overheated transmission, the fluid level will hit a dangerous level. This will force the engine to shut down, and you will have to pay for a pricey repair.

Read more: Marvel Mystery Oil Good Or Bad


Your transmission is one of the most significant parts of your vehicle. As a result, it’s vital that you understand how it works or have it checked out if you notice any signs of transmission issues. When the AT Oil Temp indicator illuminates on the dash, it implies the temperature of your automatic transmission fluid is too high. If left unchecked, transmission failure can occur. This is equally unsafe while driving and can lead to costly repairs. 

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