Transmission Light On – Meaning, Causes, & How To Fix It

The last thing you want when you start up your vehicle is to have a light on the dashboard that won’t turn off. But while you know what to do with a check engine light or a tire pressure light, what do you do with a transmission light?

What could it mean, and more importantly, how do you get it to go away? It’s a pretty common problem, but that doesn’t make it any less serious.

We’ve highlighted eight different reasons the transmission light might be on in your vehicle, and we’ve even come up with a basic troubleshooting guide to help you narrow things down.

What does the Transmission Light Mean?

The transmission light is a dashboard warning light that is typically found on vehicles equipped with automatic transmission. The light is most often a yellow or orange symbol that looks like an exclamation mark or thermometer inside a gear, but it could also be a string of text on some car models.

The light is connected to the vehicle’s on-board computer, which monitors the transmission system and alerts the driver to potential issues. When the computer detects a problem with the transmission, it sends a signal to the transmission light to come on.

The exact appearance and process for how the light works can vary depending on the make and model of the vehicle, but in general, it works the same.

If you want to know more about the transmission light or how it looks on your specific car model, it is best to consult your vehicle’s owner’s manual.

8 Reasons for a Transmission Light

As mentioned, your transmission light is there to communicate with you, but unless you know why it turns on, it won’t tell you much of anything. That’s why we took the time to highlight eight different reasons the transmission light on your vehicle might’ve turned on.

1. Low Transmission Fluid

This is one of the most likely reasons for a transmission light. Transmission fluid is supposed to stay inside the transmission, and when the fluid levels get too low, it can turn on the transmission light.

If the transmission is low on fluid you need to figure out where it’s going. The most likely reason for this is a fluid leak somewhere on the transmission. This could be a transmission oil pan gasket if you’re lucky or a front seal if you’re unlucky. Either way, you’ll need to fix the leak and fill up the transmission with new oil to fix the problem.

2. Overheating Transmission

There are a couple of reasons your transmission might be overheating, but they’re all something you need to look into right away. First, the transmission might be low on fluid. We’ve already highlighted why this might be the case with the first spot on our list, but it can certainly lead to your transmission overheating.

Another reason the transmission might overheat is that the transmission fluid is too old. Old transmission fluid doesn’t disperse heat as well as new fluid, and it doesn’t lubricate as well. This means more friction between components, and more friction creates more heat.

There could also be a blocked or clogged transmission intercooler, or there could be other components creating too much friction when the transmission is running.

3. A Faulty Shift Interlock System

When we’re talking about the shift interlock system we’re not actually talking about the shifting mechanisms inside the transmission, although they could be giving you problems too. Instead, we’re talking about external components that might keep the vehicle from shifting.

For instance, you should need to depress the brake to get out of park. But if this system fails, you might not be able to get out of park at all, or you might be able to get out of park without pressing the brake. Either one is a problem and can set off the transmission light.

4. Malfunctioning Valve Body

With manual transmissions you need to depress the clutch at the right time to shift gears. Automatic transmissions don’t have a clutch, and it’s the valve body that helps the vehicle get into the right gear at the right time.

If the valve body starts to fail, the transmission won’t work the way it should, will likely make some grinding and whining noises when shifting, and the transmission light should come on.

5. Faulty Torque Converter

The torque converter transfers the power from the engine to the transmission. It’s a critical component in your transmission, and when it’s working properly it does a great job. But there are five different primary components inside the torque converter, and if any of them start to fail it can lead to problems.

Depending on the problem depends if the transmission light will turn on, but if there’s a problem with the torque converter it probably will.

6. Electrical Problem

While there are tons of components in your transmission that use mechanical and hydraulic linkages, there are still plenty of electrical components to go around. Whether it’s the shifting mechanisms or one of the various sensors, they all need the right amount of power at the right time.

If there’s a crossed line, blown fuse, or malfunctioning relay, the transmission won’t work the way it’s supposed to. That’s going to turn on the transmission light on the dashboard to let you know there’s a problem you need to address.

7. Damaged Internal Components

There are tons of internal components inside your vehicle’s transmission. If any of them seize up, break, or end up with damage in any other way, it will affect the overall performance of the transmission.

And when the transmission isn’t performing the way it should, various sensors will pick up on it, and it’s going to throw a transmission code and light up the transmission light on the dashboard.

8. Old Transmission Fluid

Depending on the age of your vehicle, the type of transmission fluid you use, and whether it’s a manual or an automatic, you should change the transmission fluid between every 30,000 and 150,000 miles.

It’s a big discrepancy, but to figure out the recommended transmission fluid change interval for your vehicle look at the owner’s manual. Keep up with this interval, or it can start to lead to internal transmission problems.

Old transmission fluid doesn’t disperse heat or lubricate as well as new fluid, and either of these problems can lead to the transmission light turning on.

9. Faulty Sensors

Most transmissions on modern vehicles have a multitude of sensors. These sensors include the input sensors, the output sensor, the transmission speed sensor, and more. While these sensors all help improve the efficiency and performance of the vehicle, if they fail they won’t run properly and will turn on the transmission light on the dash.

How To Fix a Transmission Light

Now that you know about a few of the possible reasons the transmission light might be on, it’s time to figure out how to get it back off! We’ll address some of the basic troubleshooting steps you should complete before you decide to take your vehicle to a mechanic for repairs.

1. Inspect the Transmission

Sometimes all it takes to figure out what’s going on is a quick visual inspection. If you see transmission fluid all over the outside of the transmission that’s a clear sign there’s a leak. Meanwhile, if you see cracks or other obvious signs of damage, then that’s a pretty important piece of information too!

2. Check the Fluid

If the outside of the transmission looks fine, do yourself a favor and take a look at the dipstick. Looking at the dipstick tells you two things.

First, it tells you if the transmission is low on fluid. If it is you have to figure out where it’s going and top it off. Second, you need to look at the color of the transmission fluid. If it’s still bright red, it’s in good condition. But as the transmission fluid ages it starts to turn brown.

The browner the fluid, the older it is. Old transmission fluid can create all kinds of problems. Just keep in mind that while changing the fluid might clear up the problem, there also might be more damage from the old fluid that you’ll need to fix too.

3. Read the Code

The final thing you need to do before attempting to fix anything is to read the code with an automotive scan tool. These codes give you all sorts of information about what’s going on. For instance, if you have a code P0868 it means “Transmission Fluid Pressure Low.”

If you have that code and notice the transmission is low on fluid, that’s likely the reason for the code. You’ll still need to figure out where the fluid is going, but you also know it’s unlikely that there’s further damage.

4. Narrow Down the Problem

Once you read the code, it’s time for you to narrow down the problem a bit. While we’d love to walk you through what exactly you need to do, it all comes down to the specific code your vehicle has.

If you don’t know how to narrow down the problem further, you can complete a little research or hand it over to a professional mechanic for them to figure out what’s going on.

5. Replace the Component/Rebuild the Transmission

Once you figure out the problem, all that’s left is for you to fix it! Replace the defective part or rebuild the transmission as necessary. Once again, if you don’t have the skill set to do this, take your vehicle to a professional shop that can.

Is It Safe to Drive With Transmission Light On?

Because the transmission light comes on for a variety of reasons, some which are more severe than others, you should not continuing to drive until the potential issue is addressed.

And since repairing an automatic transmission is one of the most expensive repairs that a car can require, with an estimated cost range between $1,000 and $3,000, and potentially reaching up to $4,000 or more depending on the extent of the damage. it’s important to take action immediately.

Final Thoughts

Now that you know a little bit more about why the transmission light might be on in your vehicle, all that’s left is for you to head out and see if you can’t figure out what’s going on!

But keep in mind that the transmission light can be a pretty serious problem, so you really shouldn’t keep driving the vehicle until you figure it out.


Is the Transmission Light the same as the Transmission Warning Light?

Yes, the transmission light and the transmission warning light are typically the same thing. Both refer to a dashboard warning light that is designed to alert the driver to potential issues with the vehicle’s transmission system. The light may also be called a “transmission indicator light” or a “transmission fault light,” depending on the make and model of the vehicle. Regardless of what it’s called, the light serves the same purpose, which is to let the driver know that there is a problem with the transmission that needs to be addressed.

Is the Transmission Light only on automatic transmission vehicles?

Yes, the transmission light is typically only found on vehicles equipped with automatic transmission. This is because automatic transmissions are more complex than manual transmissions and are therefore more prone to issues that may require the driver’s attention.

Can a Transmission go out Without Warning?

Yes, a transmission can go out without warning. While some transmission issues may be accompanied by warning signs, such as the transmission light coming on, noise from the transmission, or difficulty shifting gears, it is also possible for a transmission to fail without any warning. This is why it is important to have your vehicle regularly serviced by a professional mechanic, who can inspect the transmission and check for any potential issues. Regular maintenance can help to prevent sudden transmission failure and keep your vehicle running smoothly.

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Rickard Cefalk

Rickard is the owner of and a dedicated and avid do-it-yourselfer who has always enjoyed working on his own vehicles since childhood. He now devotes his time to sharing his expert knowledge of car maintenance and other car-related information through his website.

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