Symptoms Of A Bad Transmission Valve Body

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automatic transmission valve body

The transmission valve is the heart of your car’s engine. It controls the flow of fuel and air, which in turn dictates how much power you get to use when you step on the gas. If it gets stuck or breaks down, it can cause all sorts of problems for your vehicle.

The symptoms that indicate a bad transmission valve are not always easy to spot because they could manifest themselves differently depending on what type of problem is present with your engine.

This article discusses the symptoms of a bad transmission valve body. Noticing any of these symptoms means your vehicle needs attention and it’ll allow you to prevent irreparable damage. So, let’s get started.

What is a Transmission Valve Body?

new valve body

A transmission valve body is a maze-lie control center that consists of multiple solenoids, passages, and valves. The primary function of this component is pretty simple despite its complex structure. It directs transmission fluid where it’s needed and helps your vehicle to shift gears smoothly.

Getting the transmission fluid to the right place becomes difficult for any vehicle if its transmission valve body isn’t operating as it’s supposed to. Not only can it damage the transmission of your vehicle but it can also make the driving experience difficult for you.

How Does an Automatic Transmission Valve Body Work?

entire transmission

Before we discuss the symptoms of a bad transmission valve body, it’s important to understand how this component actually works. Having a solid understanding of the working procedure of this critical component is important so that you can monitor its performance and determine whether or not it needs replacement.

The transmission valve body in your car functions by using hydraulic fluid and moves it around through multiple channels to manage and regulate proper gear shifting and clutch engagement. It controls all hydraulic circuits of gears by using an electric solenoid valve and sensors.

It controls your gear shift manipulation and allows you to shift from one gear to another. If the transmission valve body is unable to move transmission fluid and get it to the right place at the right time, it’ll be impossible for your vehicle to shift gears.

What are the Types of Transmission Valve Body?

Primarily, there are two different types of the transmission valve body.

Electronic Valve Body

The first type is called the electronic valve body and most modern cars are equipped with it. It uses ECT (Electronic Controlled Transmission) that comes with clutches and bands operated through hydraulics.

The electric solenoid of the electronic transmission valve body makes it a more advanced and elaborate controlled scheme as compared to non-electronic ones as it controls all the hydraulic circuits. The transmission controller can also monitor engine speed, anti-lock braking system, vehicle speed, and throttle position.

Hydraulic Valve Body

The other type is known as the hydraulic valve body. As the name implies it controls all the valves connected to the shifting level by using hydraulic pressure. In order to accommodate the change in the handle’s position, it covers and uncovers different valve body passages.

For example, the transmission fluid will be transferred to the clutch to activate the first gear if you put your vehicle’s gear lever to drive.

What Components of a Transmission Valve Body Houses?

The following components are located inside your vehicle’s transmission valve body:

  • Shift valve
  • Throttle valve
  • Shuttle valve
  • Manual valve
  • Pressure regulator valve
  • Vacuum valve
  • Governor valve
  • Kick down valve

Can you drive with a bad transmission valve body?

You should not—we emphasize, not—drive with a faulty transmission valve body for too long. A minor problem with your transmission valve body may develop into a major issue with your whole transmission over time. When you have an ineffective transmission valve body, you’re putting a significant strain on your car’s engine.

Bad Transmission Valve Body: Symptoms

Typically, having a bad valve body symptoms are noticeable. You might not be able to drive your vehicle for too long because it makes the driving experience very frustrating. You’ll have difficulty changing gears and you might also hear some odd sounds.

Here’s a list of some of the most common symptoms of a bad transmission valve body. We recommend you get your vehicle fixed as soon as possible if you notice any of the following symptoms.

Wrong Gear Change

On any automatic gearbox, the transmission valve body works as the main control system for changing gears. It’s designed to efficiently respond to the throttle pedal that you have. It also shifts gears at the right RPM in order to ensure better fuel efficiency.

However, if you’re noticing that your vehicle is changing the gears at the wrong time and affecting the fuel efficiency, it can be a sign of a bad transmission valve body. For example, you can notice gear skipping or down or upshift when you were not expecting.

In this scenario, you must take your vehicle to your mechanic to get it checked right away to avoid further damage.

Slipping Transmission

Experiencing clutch slip isn’t something new to drivers with manual cars. But it’s certainly not a good sign if you have a car with an automatic box. It happens when you try to accelerate your car by lowering the throttle pedal and the RPM increases but your vehicle doesn’t speed up,

On a manual box, the culprit is a worn-out friction plate most of the time but there could be multiple reasons when it comes to automatic cars. It can be a valve that’s failing to extend as it’s supposed to or it has started sticking inside the valve body assembly.

Resultantly, it keeps gears from engaging properly and they start slipping as you lower the throttle.

Banging or Knocking Sounds

If you hear knocking or banging sounds while shifting gears like going from drive to reverse or opposite, then your vehicle most probably has a flawed transmission valve body. You may also hear odd noises while applying brakes.

It’s important to note that if you’re only hearing weird sounds when you step on your brake pedal, then it might not be a problem with your transmission valve body. But if it’s happening while changing gears as well, then you must not rule out the possibility of a faulty valve body.

Sharp Gear Changes

If your vehicle has a bad transmission valve body, you might also experience that the process of changing gears is becoming harsher. Every automatic vehicle is designed to have smooth gear shifting to improve the driver’s comfort and experience.

You might experience that your car jerks forward a little every time it changes gear. Bear in mind, this problem only gets worse with time and if you leave it unchecked, then you’ll need to replace your transmission valve body.

Not only will it cost you a whole lot of money but also time and effort. Therefore, get your car checked as soon as you can if you’re experiencing sharp gear changes.

Not Changing Gears

As well as wrong gear change, you can also experience that your vehicle is not changing gears as it should if the transmission valve body is faulty. This symptom is noticeable if you know how your vehicle works and when it changes gears as you accelerate or slow down.

On the other hand, you might not be able to notice this sign if you’ve bought the vehicle recently. In this case, you’ll need to look at the RPM reading when the gear shift happens. If it’s delayed then your car requires diagnosis.

Transmission Fluid Leak

hydraulic fluid leak

This symptom will only be visible if you have a vehicle with a hydraulic valve body system. In this type of system, the transmission fluids are pulled or pulled across different galleries to disengage and engage different valves. The fluid keeps all the chambers of the transmission valve body lubricated and keeps it from overheating.

The leakage of transmission fluid is not usually but when it happens, the valves inside the body fail to operate efficiently. If you have a car with a hydraulic valve body system, then consider inspecting for leaks once in a while is an effective method to catch an oil leak.

Unable to Downshift

If your car isn’t able to downshift then the most probable culprit is a bad transmission valve body system. In this situation, the transmission fluid fails to navigate properly to the right place and the vehicle can’t pressurize the gears to downshift. Not only does it break the driving experience but it also degrades the performance of your car greatly. You might also experience difficulty maintaining a constant speed on the road or speeding up the vehicle.

Check Engine Light

If you notice any of the symptoms that we have discussed so far, then it’s highly likely that your car’s MIL (Malfunction Indicator Lamp) or check engine light will turn on. You must take your vehicle to the mechanic or use an OBD2 scanner yourself if you’re a DIY enthusiast for proper diagnosis.

You’ll find some trouble/error codes that will inform you regarding the exact problem. The most common error codes related to the transmission valve body system are P2707, P0829, P0783, P0751, and P0715.

It’s important to note that many people take small symptoms for granted in the beginning. But even the slightest symptoms of a bad transmission valve body can result in devastating and irreversible consequences.

Can You Continue Driving After Noticing Any of These Symptoms?

Driving your car with problems for too long is never a good practice. You can only go so far by ignoring the check engine light or turning on your vehicle’s radio louder so that you don’t hear the banging or knocking sounds.

Whether it’s a problem in your transmission valve body or any other part, it’s destined to become worse with time. The minor problems will become major and you’ll end up having an unresponsive car that needs the replacement of expensive parts.

That’s why you must not waste time and take your vehicle to an auto repair shop right after noticing any of the aforementioned symptoms.

What is the Cost of Transmission Valve Body Replacement?

transmission valve body properly

Replacing your vehicle’s transmission valve body isn’t cheap and that’s why many car enthusiasts like to do it on their own. Not only does it cost a lot of money but it also takes at least 2 to 3 hours even for an experienced mechanic.

According to AAA (American Automobile Association), the replacement cost of a transmission valve body ranges from 300 to 1000 US dollars on average. You can go to the AAA official website to calculate the transmission valve body replacement cost accurately depending upon the year, model, and make of your vehicle.

The cost includes both parts and labor. Keep in mind that the cost varies depending upon your vehicle. For example, if you own a luxury car such as Volvo or Mercedes-Benz, then you should expect to pay even more.

If you’re on a budget then rather than purchasing a new transmission valve body, we recommend you buy a remanufactured one that’ll allow you to get away by paying less. However, still, the cost that you’ll need to spend on replacement will be astronomically higher than the repair cost.

So the best-case scenario is to get your transmission vehicle body checked if you experience any symptoms.

Should You Go For Transmission Valve Body Replacement?

If you want to keep driving your car in the foreseeable future, then spending money on the transmission valve body replacement is worth it. But if you own a very old car that doesn’t even worth a thousand dollars then spending the same amount of money to replace a transmission valve body might not be a good idea.

Tips for Keeping Your Transmission Valve Body in a Good Condition

The most important advice to keep your car from having a bad transmission valve body is proper maintenance. Considering your vehicle to your mechanic regularly is the best way to find out and fix problems in your transmission valve body.

It’s also important to use a high-quality transmission oil because you don’t want to experience heat and sub-par lubrication issues. A bad quality oil can also decrease the lifespan of key components. So in the long run, it’ll be cheaper to use high-quality transmission oil than to get the entire gearbox rebuilt.

Last but not least, you must keep an eye on your check engine light. It only turns on if some abnormal behavior is detected and that’s why you must never ignore it.


Transmission valve body replacement isn’t a cheap process and you should seek help from a professional mechanic if there are any symptoms. If your transmission is working properly, then the best thing to do is take care of it by using high-quality oil and making sure that you go in for regular maintenance. Make sure not to ignore the check engine light as this could be one sign of an issue with your vehicle’s transmission valve body.

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