How To Fix The AT Light On Mazda 3?

Did you have difficulty starting up your Mazda 3 one morning and heard a clanking noise? Or maybe you were driving when your Mazda 3 slightly jerked like it was having a hard time shifting gears? You can stop puzzling over the issue because we can answer the question for you here.

Follow the steps below to fix or reset the AT light on your Mazda 3:

  1. Turn on the ignition without turning on the engine.
  2. Step on the gas pedal all the way to the floor and hold it there for 30 seconds.
  3. Release the gas pedal.
  4. Turn off the ignition, then turn it back on again all the way to turn on the engine. The AT light should now go away.

Keep in mind, however, that this is not a real fix. These steps will only reset the AT light, which is a notification that there is something wrong—you’re getting rid of the notification without addressing the problem that triggered it. There is a high possibility that the AT light will keep coming back unless the underlying cause is addressed.

So, what are these underlying causes that could have triggered the AT light? Read all about them in the succeeding sections, including the symptoms for each one. Read on!

all new Mazda 3 Fourth generation at Geneva International Motor Show, compact car manufactured in Japan by Mazda - How To Fix The AT Light On Mazda 3

How to fix the AT light on Mazda 3?

The “AT” on that light stands for the automatic transaxle, which refers to the transmission system of your Mazda 3. Thus, if you see the lit-up AT light on your dashboard, it is trying to alert you to a possible problem with a component of the transmission system.

The transmission system is one of the more expensive systems to replace and repair. So, it pays to keep it well-maintained. Fixing what triggered the AT light in the first place is the true resolution to the AT light issue.

What is the AT?

Let’s talk about the “AT” on that warning light. Knowing where the problem could be coming from is the first step to fixing it.

The AT or your automatic transaxle is responsible for changing gears without the need for any input from you. It is usually composed of the transmission, the axles (this is why it is sometimes called the transaxle), and the differential.

Automobile transmission gearbox in sections, car gearshift

What triggers the AT light to come on?

Your Mazda 3 is built with many sensors that detect issues that could affect the health of your engine. This includes the components that allow your car to run, and the transmission system is a good example.

The AT light is triggered by Mazda 3’s onboard computer once a sensor detects a possible problem with the transmission system.

There are times when the AT light will trigger along with the check engine light. They could be pointing to the same problem or to two separate problems that are related. We will be focusing on the transmission problems in this article.

Low transmission fluid

Your Mazda 3’s onboard computer will ignite the AT light once it senses that the transmission fluid is at a low level. But how do you know if your engine is low on transmission fluid?

The Mazda 3 has a transmission dipstick that you can use to check the transmission fluid level. It is a rod with an orange-colored rubber-like coating near the battery box that you can pull out.

After you pull out the transmission fluid dipstick, you will see four marks near the bottom. There are two 20 degrees Celsius marks and two 65 degrees Celsius marks.

To check the transmission fluid, start the engine and go through each gear from the park mode, waiting for three to five seconds before moving to the next. Once you’ve reached the drive gear, wait for five seconds, and put the gear back to park mode but leave your Mazda 3 running.

Pull out the transmission fluid dipstick. The transmission fluid level should be between the lower and upper markers on the 65 degrees Celsius markers. Add transmission fluid if the level is less than the lower marker.

Wait for your car to cool down for around four to five hours. Then add transmission fluid into your Mazda 3 using a funnel after pulling out the transmission fluid dipstick. Keep adding transmission fluid until it reaches the area marked 20 degrees Celsius.

Turn on your Mazda 3 once the transmission fluid is within the lower and upper limit marks of the 20 degrees Celsius area. Check the transmission fluid level once more. Make sure that it is within the 65 degrees Celsius mark.

The Castrol Transmax is an automatic transmission fluid that meets Dexron requirements. Check it out on Amazon.

Transmission issue

What if the transmission fluid is at the normal level? The next step is to use an OBD-II scanner, although this is only possible if you have an OBD-II scanner.

If you do not have an OBD-II scanner or if you do not know how to use one, then it is best to bring your Mazda 3 to a mechanic or a service center. The OBD-II scanner can help pinpoint the specific transmission problem that your Mazda 3 is having.

The BlueDriver Bluetooth Pro OBD-II scan tool for iPhone & Android is available. Check it out on Amazon.

What to do when the AT light comes on?

It is important to slow down and stop at the earliest possible time once you see the AT light go on. It is common to notice that your automatic transmission cannot shift higher than the third gear. There are even times when your transmission will not be able to shift down from third gear.

This can be dangerous, which is why it is advisable to stop your Mazda 3 at the first safe opportunity. You might even notice that there are no lights on the dashboard where it tells you what gear you are on.

Transmission problems in Mazda 3

A new Mazda 3 on a country road

The following are the common transmission problems on Mazda 3.

Instead of the usual way of listing the name of the problem and then the symptom, this list starts with the symptoms first. This will make it easier for you to find the symptom that you’re experiencing and then match it with the description of the problem.

Not all the symptoms below will include a DIY fix because transmission problems are among the most complicated problems that you can encounter in a car—not just with Mazda 3.

Clunking, whining, or humming sound

These sounds can vary with the Mazda 3 trim and model version, but you should be able to describe these sounds as either one of these three.

Manual transmissions produce a more noticeably mechanical sound. It is also louder and harsher sounding.

If you usually hear these sounds whenever your Mazda 3 tries to shift gears, the sound could be coming from the differentials. Thus, the problem could be in the differentials.

Shaking or grinding

You should always experience a smooth ride from your Mazda 3. Once it stops giving you a smooth ride, then it could be a sign of a problem.

If you experience shaking or jerking that can be accompanied by a grinding sound, then your Mazda 3 is likely experiencing a gear problem.

A Mazda 3 with manual transmission can produce a grinding sound whenever you shift gears. If you experience this grinding after stepping on the clutch and shifting, then this could be a sign that the clutch requires a replacement.

This can be caused by several issues, the most common of which is a worn-out gear synchronizer.

Mazda 3 with automatic transmissions might react differently. It could feel like it is taking a long time to get into gear instead of producing grinding sounds. It will no longer give you the usual smooth gear shifting.

You can experience more jarring and shaking as the problem worsens.

all new Mazda 3 Fourth generation at Geneva International Motor Show, compact car manufactured in Japan by Mazda

Noise in neutral gear

You might hear a bumpy sound whenever your Mazda 3 is in neutral gear. This can be caused by dirty transmission fluid.

Check the transmission fluid level. Add more if it is less than the recommended level. If this did not get rid of the noise, then it is certainly because of dirty transmission fluid. Dirty transmission fluid should be completely drained and then replaced.

The noise can also be caused by worn-out transmission parts like bearings or reverse idler gears.


Have you noticed if your Mazda 3 seems to hesitate to get to a higher (or lower) gear? The way your Mazda 3’s transmission system is designed, your transmission should automatically go to the proper gear once you move it to drive mode. Delays in engaging the correct gear are normally a transitioning-related problem.

Mazda 3 variants with manual transmissions can experience a slight delay. This delay can be accompanied by a sudden surge in the engine’s RPM, but there is no movement from your car.

This is usually caused by a worn-out clutch that can only be fixed by replacement. Unfortunately, this can also be a symptom of more severe issues.

Burning smell

Any burning smell in a car is always a cause for concern. A burning smell is usually a sign of burning transmission oil that keeps the parts lubricated and prevents wear.

A low fluid level (or when you’re using the wrong type of fluid) can cause the transmission system to run hot. High temperatures in the transmission area can be caused by increased friction, corrosion, and accumulated dirt, debris, or sludge. Needless to say, this can badly damage the system which can lead to expensive replacements.

We have an article here about the possible causes of a Mazda 3 that will not start.


Mazda3 all new (2015) car running on the moutain road

Resetting or fixing the AT light on your Mazda 3 is a simple activity that should be avoided unless you have already addressed the underlying cause. It is a good idea to address the underlying cause immediately because it can be dangerous to ignore.

If you enjoyed this article, check out this article about the average width of cars.

A new Mazda 3 GT hatchback vehicle on a car dealership lot displayed in front of the showroom, How To Fix The AT Light On Mazda 3?

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  1. Awesome fix took my air bags off my 2006 MX5 and te check engine and AT light came on. Used the above step and instantly worked thanks

  2. I have experienced while driving this morning my transmission clunking and then AT SYMBOL turned on and suddenly turns off again.

  3. When I go to start my car, the AT light comes on with smybol of a car with a key flashing,it wont turn on. after awhile the AT light goes out and then you have to wait 10 seconds, then it will turnover.2003 Mazada

  4. I have a 05 Mazda 6 I crank it up but once I put it n drive it hesitate . To move the at lights comes on wat causes it not move

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