8 Reasons Why Your Car Downshifts Hard While Slowing Down

Have you come across the problem when the transmission inexplicably downshifts hard while slowing down, and you want to learn why this is the case? Well, if that is the case, you are in the right place because, in this article, we are going to cover everything you know about this problem.

Doing your own research on a problem is the way to go if you want to be able to diagnose some of these issues and learn more about what they represent and also the causes of why they appear. This is why we are here to help you out.

We’ve previously talked about the 14 common signs of transmission problems and we’re also specialized for CVT transmission problems here at Life On Four.

First, we are going to cover the causes of this problem, then we are going to discuss how to fix the problem and also how to prevent it. Then, we are also going to learn the cost to fix this problem. So, without further ado, let’s dive in.

Causes For Hard Downshifting

Now let’s cover the causes for the problem when the transmission inexplicably downshifts hard while slowing down and learn more about the possible root for this issue.

Knowing the causes is always useful since you can easily determine the amount of money that will be needed for a fix of the problem.

1. Low Transmission Fluid

The most common cause for the problem when transmission inexplicably downshifts hard while slowing down is the situation when you have low transmission fluid.

As you probably know, transmissions use a fluid known as ATF. This is a red fluid that is also known as hydraulic fluid. This fluid makes all gear shifts possible.

Sometimes this fluid starts to leak from the transmission, or if there is an oil cooler it can leak from the hoses.

If the fluid level gets too low, the transmission will not have enough fluid to function properly. In this case, you will end up with a problem when the transmission shifts rough.

This is why it is useful that you check the transmission level every once in a while. If you didn’t know, transmission fluid is only checked when the transmission is warmed up. If you check the fluid when the transmission is cold, you will get a wrong reading.

2. Dirty Or Burnt Transmission Fluid

The second most probable cause for the transmission downshifting hard is dirty or burnt transmission fluid.

As we noted previously, transmissions are using ATF, also known as hydraulic fluid in order to work properly and deliver shifts.

This transmission has a lifespan and usually lasts for about 60,000 miles. When the life of the fluid is spent, this transmission fluid will be burnt and will not deliver good shifts, and will cause many problems running the car.

You can check the transmission fluid condition by removing the dipstick and if the transmission fluid has turned brown, it means that it is time to be replaced.

Another reason that is closely related to burnt ATF is the condition when the fluid gets dirty. This is happening because the transmission during its use releases debris.

There could be metal flakes, clutch material, and gasket material. All these small particles will make the transmission’s life difficult and your transmission will not deliver good shifts.

So, if it shifts hard, it is time to check the fluid condition and see if the fluid is due to be replaced with fresh fluid.

If the fluid has changed color and does not look pinkish, and if the fluid has some debris running through it, it means that it is time for the fluid to be flushed and replaced.

3. Wrong Transmission Fluid

Another reason for the situation when transmission inexplicably downshifts hard while slowing down is using the wrong transmission fluid.

Let’s say that you did the service and you replaced the fluid on your transmission and you start to experience problems. If this happens, this is highly likely because the transmission fluid that was added is not the right one for your transmission type.

In this situation, you will have to redo the service all over again and flush the wrong fluid. This is the case because a lot of people are inexperienced and use the wrong fluid instead of using the proper fluid for that specific transmission.

And nowadays with the invention of CVT transmissions, we see this more and more often. Even though these transmissions are both automatic. They don’t use the same fluid. CVTs are using different types of fluid compared to classical automatics.

So, before you do any type of service to your car, you need to learn which fluid works best for your transmission and make sure that you add the right fluid in order to avoid problems such as this in our situation.

If you are inexperienced, make sure that you visit a shop that specializes in vehicles such as yours and they will highly likely have the exact fluid that your transmission needs.

4. Dirty Transmission Fluid Filter

Another common cause for the problem when transmission inexplicably downshifts hard while slowing down is the dirty transmission fluid filter.

Every automatic transmission has a filter that is designed to trap the metal particles that are inside the fluid.

Sometimes these filters get so blocked out that the fluid doesn’t flow very well. This prevents the fluid from reaching the valve body and allows proper shifts.

So, when the filter is too clogged up, you will start to experience hard shifts and overall poor transmission work. This is why when you flush the transmission fluid, you should always replace the filter and clean the transmission pan in order to get rid of these nasty particles that can cause problems such as this in our case.

Usually, there is a kit where you get the filter and a new gasket for the pan. And getting these parts should be one of your top priorities whenever you intend to do this service.

5. Bad Shift Solenoids

Bad shift solenoids can also cause the transmission to shift poorly and not deliver when it comes to shifting. So, what are these solenoids and why is this the case?

The solenoids are electronic actuators that are controlled by the TCM, also known as the Transmission Control Module. These actuators open and close. They are basically letting the fluid travel throughout the valve body and deliver shifts.

Whenever these solenoids are not opening and closing correctly, you will get the check engine light and other symptoms such as hard shifting.

Luckily, replacing these solenoids is not something expensive to do. It will cost you a few hundred dollars in the worst-case scenario. And after you replace the solenoid, the car’s transmission will work like new.

6. Valve Body Failure

Valve body failures are also common in automatic transmissions. So, what is the valve body?

Well, the valve body as its name implies is the component located on the bottom of the transmission where the valves (solenoids) are located that we previously covered.

This valve body is a maze-like structure where the fluid travels and delivers the shifts. Sometimes these valve bodies tend to fail or get blocked up and when they do, you will start to experience problems with shifting and sometimes the transmission will even completely stop working.

Luckily, there are many parts available on the second-hand market and you can find one of these units for a superb deal. There are plenty of refurbished valve bodies on sale on eBay.

7. Problems With the TCM

The TCM or Transmission Control Module can also fail and cause problems such as this when the transmission downshifts hard while slowing down.

The TCM in general is the computer that controls the transmission. And this unit like with every other computer can fail and cause problems to develop.

In most cases, when the TCM fails, there will be symptoms such as in our case and also, there will be the check engine light with different types of codes concerning the transmission.

What is bad is that diagnosing these units is rather difficult and the only method to diagnose one is to replace it with the same unit from a different car or a new TCM or a refurbished one. If the codes are cleared and the shifts are good, this TCM was the main culprit for this problem.

8. Worn Out Transmission

And the last cause for the situation when transmission inexplicably downshifts hard while slowing down is the worn-out transmission.

Sometimes, the transmission can fail on the inside and cause problems such as these. So, if your car has a lot of miles on this transmission and has never been rebuilt, you might be safe to assume that the problem is caused by a worn-out transmission.

This of course has to be properly diagnosed by a technician and the transmission has to be disassembled in order for the real root of the cause to be investigated.

How To Fix Hard Downshifts While Slowing Down

We covered the causes for this problem, now let’s learn more about how you can fix the issue on your transmission. In other words, what can you do in order to tackle the problem?

The first thing that you want to do is to check the level of the transmission fluid. You can do this by warming up the car and leaving the engine running for a bit and then removing the dipstick so you can check for the level. Only after the transmission is warmed up you will get a proper reading.

If the fluid is low, top it off and this will hopefully solve the problem. If the fluid is dirty on the other hand, you will have to flush the fluid on your car with brand-new fluid. Also, replace the filter in the process.

If the problem still persists, you will have to perform computer diagnostics in order to check if the solenoids or the valve body are causing issues.

If you get codes concerning these components, you will have to replace the solenoid or the valve body.

Still, we recommend that you visit a shop that is working with transmissions and let them sort these issues out. Since the transmission is located at the bottom of the car, working around it can be somewhat dangerous for the inexperienced.

How To Prevent Hard Downshifts While Slowing Down

Preventing this problem can be somewhat difficult because you can never know what could be causing the issue in the first place. Since there are many of these causes that can trigger an issue such as this.

But we can advise that you do regular maintenance on your car. Flush the fluid when the fluid reaches the service interval.

You also need to check your fluids regularly and make sure that they are topped off. This is the basic preventive maintenance that every car owner should do in order to avoid issues such as this.

And if the vehicle is a bit older, you will highly likely have to add some ATF. This is nothing too scary. The important thing is to make sure that the transmission is never left on low fluid because only then, major issues might come along that can be very expensive to fix.

Repair Costs

Repairing a problem such as this is not something crazy expensive and will most likely not require the transmission to be rebuilt (especially if you take action as soon as you notice the first signs of problems).

The problem most often lies in the transmission fluid or possibly the solenoids. In the worst-case scenario, you will have to pay about $500 for a solenoid replacement or up to $250 to flush the fluid.


The problem when transmission inexplicably downshifts hard while slowing down can be really annoying to deal with. But luckily the issue is not that scary in the first place.

This problem is most likely triggered by low fluid level or dirty fluid. Sometimes, blocked transmission solenoids can trigger the issue.

The important thing that you should do when this problem appears is to check the fluid levels and top off the fluids in order to avoid some major transmission damage.

Running the transmission at the right fluid level and having the fluid nice and fresh should be one of your top priorities. Only with fresh transmission fluid, the transmission can regain its functionality to 100% and lube all the moving parts inside the transmission.

If the problem persists, the issue has to be more thoroughly diagnosed and addressed by professionals. There are many shops across the country that are working with transmissions, just make sure you choose a reputable repair centre.

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