Home TroubleshootingEngine Dirty Throttle Body Symptoms: What You Need To Look Out For

Dirty Throttle Body Symptoms: What You Need To Look Out For

by Kelvin Yates

A rough idle and jumpy acceleration can be the most common dirty throttle body symptoms. Whenever you hit the gas pedal you expect your car to move, right? But a dirty or malfunctioning throttle body might get in the way of that. You might not realize it but a throttle body is a reason why your vehicle actually starts to move.

The throttle body is one of the most essential mechanical parts found in a car. It is usually found in fuel-injected vehicles. Throttle bodies are responsible for regulating the amount of fuel-air ratio in the engine. When the throttle body is in its optimum condition, the engine receives the ideal air-fuel ratio and the perfect performance. However, the combustion process will not occur properly if the throttle body gets damaged.

What Is A Throttle Body

When we talk about the traditional internal combustion engine, the throttle body classifies as a part of the intake system. It is responsible for controlling the amount of air and fuel that is pushed into the engine’s combustion chamber. The throttle body consists of a housing unit that contains a throttle plate that is placed on a shaft.

A throttle body is a tube-shaped housing that contains a flat valve as said before. This flat valve or a butterfly valve rotates according to the amount of air entering the engine. In an electrically fuel-injected car, a throttle position sensor and mass air-flow sensor communicate with the ECU. this further supplies the engine with the correct amount of fuel and air given by the injectors.

When the accelerator or the gas pedal is pressed, the throttle plates open up allowing the air to flow into the engine. When the gas pedal is released, the butterfly closes and effectively chokes off the airflow into the combustion chamber. This process efficiently controls the speed of the vehicle and the power produced by the car.

Where Is The Throttle Body Located

When we talk about old carburated engines, the throttle body is usually built into the carburetor itself. It is opened and closed with the help of a cable and linkage from the gas pedal and engine vacuum. More fuel is released into the combustion chamber as the valves open.

On the other hand, in a fuel-injected engine, the throttle body is usually located between the air filter and the intake manifold. It is connected to the gas pedal mechanically with a cable or electronically with the help of a wire. When the presses the pedal the butterfly in the throttle body pivots to let more airflow.

When that happens, the throttle position sensor reports to the ECU that you have stepped on the gas. And the airflow sensor detects more air and sends a message to the car’s computer to boost the amount of fuel being supplied by the injectors.

Symptoms Of A Dirty Throttle Body

When we talk about modern cars, the throttle body is one of the most important pieces present in the air intake system of a vehicle. As said before it is responsible for the amount of air that flows into the engine, which further burns with the fuel in the cylinders.

At any given time, for the engine to run at its optimum condition, the throttle control unit is responsible for sending the correct amount of fuel-air ratio for the best power output. When this throttle body is malfunctioning or clogged up, it hinders the flow of air into the engine which causes issues with the performance of the car.

It does not only cause issues with the optimum running conditions of the engine but it also sends unburnt fuel to pass through the exhaust system. This can be extremely problematic for your car in the long run. Here are a few dirty throttle body symptoms that might help you figure out what is causing your car to have problems.

Dirty Throttle Body Symptoms #1: Lack Of Power

One of the most common dirty throttle body symptoms is the lack of power that your car will face. As said before the throttle body is responsible for sending the air into the combustion chamber for optimum power.

When the throttle body is malfunctioning or is clogged, there is either excess or less air entering the combustion chamber. This further causes a lack of power and the car does not accelerate as it should.

When you press the accelerator, ideally the throttle body allows a certain amount of air. Excess air and fuel comes into the engine to produce more power and increase the car’s speed. If the throttle body is malfunctioning there won’t be enough air and therefore there will be no surge in power.

Dirty Throttle Body Symptoms #2: Issues With Acceleration

Another one of the dirty throttle body symptoms is a lack of power produced by your vehicle. A malfunctioning throttle body either allows more air into the air-fuel ratio or decreases the amount the air that is needed for optimum combustion. As said in the last point, with a lack of power, the acceleration of the car will definitely have some problems and be hindered.

Any car facing problems with the throttle body will have issues regarding acceleration. Either there will be uneven acceleration or the car would not accelerate after a point in time. Both of these issues can cause problems with the power produced by the car and the mileage of the car will drop quite a bit. There will also be some major problems with the life of the engine.

Dirty Throttle Body Symptoms #3: Higher Or Lower Ideling

Another one of the many dirty throttle body symptoms is the fact that your car either has higher or lower idling than usual. One of the biggest tells of a throttle body not working efficiently is a poor and low idle.

dirty throttle body symptoms

This also includes the fact that the engine will start stalling once the car comes to a stop. The symptoms also include low idling after starting the car or a stalling car once you aggressively press the accelerator pedal.

The dirt or debris collected on the throttle body causes a hindrance to the airflow into the system. This causes the system to be turbulent and further leads to some fluctuating in the idle speed. A fluctuation in the idle of the car can be extremely problematic to your vehicle’s engine health in the long run.

Dirty Throttle Body Symptoms #4: Engine Misfires

The next on the list of important dirty throttle body symptoms is the fact that your car will misfire while facing this problem. Misfires usually occur when there is a problem with the air-fuel ratio.

It usually happens when the air-fuel ratio is very wrong or when there is a weak spark from the spark plug. In layman’s terms, a misfire occurs when there is incomplete combustion inside the combustion chamber. Misfires can mean that your vehicle’s engine condition is not optimum.

As said many times in this article before, a dirty or a malfunctioning throttle body messes up the air-fuel ratio which might be the root cause of your engine misfire. Misfires are usually recognized as small bumps that take place when you rev your engine. They are something that usually happens in a lot of old cars. Especially the ones who haven’t been taken care of properly.

Dirty Throttle Body Symptoms #5: Check Engine Light

One of the most common dirty throttle body symptoms has to be the check engine light. A check engine light is there to notify the owner of the car that there is something wrong with the engine on your car. Like any other part of the engine, the throttle body also has several sensors that are installed to make sure it works properly.

dirty throttle body symptoms

As soon as any one of these sensors detects a problem, they communicate it to the vehicle’s onboard computer and it causes the check engine light to turn on.

There are several other reasons too why the check engine light illuminates. Hence it is best for you and your car to show it to a specialist as soon as possible. You need to get your car scanned for any trouble codes that might be causing the check engine light. It is important for keeping you and your car safe.

Dirty Throttle Body Symptoms #6: Poor Mileage

Another one of the problems on the list of dirty throttle body symptoms is the fact that your vehicle will experience extremely bad fuel economy. The choking of the throttle body can be of a huge impact on the fuel economy of your vehicle. The best way of measuring the mileage in your vehicle is through the full tank to full tank method.

You need to first put a full tank of fuel and make a note of the odometer reader or you can reset one of the trip meters to zero and only then use the car. Once the tank is empty, fill up the tank again and repeat the whole process again.

Divide the distance traveled by the amount of fuel consumed. This will give you an idea of your car’s mileage. If the difference between the two full tanks is more than 15%, there is a high probability that your vehicle is facing throttle body issues.

Dirty Electronic Throttle Body Symptoms

The cars produced in today’s day and age are more technologically inclined. In older cars usually, the throttle body is controlled with the help of a cable. On the other hand, newer cars use sensors to inform the ECM (engine control module) if there is something wrong with the car. They usually inform the ECM about the position of the gas pedal, when it fails, and if there is any problem with the throttle body.

These symptoms can be extremely problematic and a little dangerous for the health of your car. Some of these electronic dirty throttle body symptoms include idle surges, and engine stalling, and a check engine light. Ignoring a faulty ETC will not only cause your engine performance to suffer but it can be a safety hazard as well. Here is a list of all the dirty electronic throttle body symptoms.

dirty throttle body symptoms

1. Acceleration Issues

One of the scarier electronic dirty throttle body symptoms is the fact that your car will experience some acceleration issues. Cars might suddenly start to accelerate for no reason. This can not only be extremely problematic for your car but also for your safety.

This is one of the possibilities if your TPS fails. A TPS or a throttle position sensor is a piece of technology that is used to monitor the air intake of an engine. This sensor is usually placed on the butterfly shaft so it can easily monitor the position of the throttle.

A failed TPS may also result in a lack of power, where you are able to start the car but it does not run for too long.

2. Sporadic Idle

Another symptom on the list of electronic dirty throttle body symptoms is sporadic and odd idling. If your throttle positioning sensor experiences some problems with the throttle body, your car will most probably experience random idle surges. These idle surges might go on for while then the engine dies.

Alongside sporadic idling, your may also notice your vehicle having a rough idle, misfire, or even engine stalling. It is possible that your car will idle either too high or too low.

3. Flashing Check Engine Light

An electronic dirty throttle body symptom is the illumination of the check engine light. Car engines are designed to run in perfect condition or as efficiently as possible. That is why when a part of your engine is not working, it can throw the entire system out of balance.

check engine light warning dashboard

This is the exact purpose of the check engine light. That is why if any of your sensors indicate a problem with the throttle body sensors, you get notified by a flashing indicator light. This is similar to the flashing check engine light in a Ford.

A check engine light can mean a lot of things as there are several sensors in modern cars. Hence it is safer to show your car to a mechanic as soon as your check engine light pops up. If you do not get your check engine light fixed, it may lead to some serious problems down the line.

Problems After Cleaning Throttle Body

Cleaning the throttle body can be an extremely difficult process. If not done properly, it can cause some damage to your car and can be the root cause of some scary problems. There are several reasons why a throttle body might misbehave.

Most of these problems usually arise after cleaning this component. It sounds odd that cleaning a component might create more problems, but if not cleaned properly the throttle body can face some problems. Here is a clearer picture of what actually happens.

1. Dirt Build Up

One of the most common problems with cleaning the throttle body is the dirt build-up inside the throttle body. Usually while cleaning the butterfly play there is usually some debris left that might cause this component to choke up. A clean throttle body is also a dust magnet that might clog up the throttle body. This is why you need to be extra careful while cleaning the components.

2. Poor Fuel Economy

Poor fuel economy means that your car is burning more fuel than required for less mileage. If you notice a drop in the number of miles per gallon that might be an indication that there is a problem with the electronic throttle body.

The fuel economy of a vehicle is not always constant. There will always be a 10% to 15% increase or decrease depending upon the driving conditions and the road conditions. But if there is a significant drop in the fuel economy, the throttle body has not been cleaned properly and might need to be unclogged again.

3. Electrical Issues

When cleaning the throttle body, you need to make sure that each and every part is cleaned properly. This includes getting rid of dirt and grime on all the sensors. When covered in dirt, the throttle body sensor will send wrong and inaccurate signals to ECU causing the engine to not work efficiently.

A dirty sensor can misinterpret information and cause more damage than good to your car. Whenever a car is experiencing any electrical issue, the car shifts to the reduced power mode causing poor power delivery and an uncomfortable drive.

4. High Idle

A high idle is a clear tell of a faulty or dirty throttle body. You will notice your car stalling when you accelerate rapidly or when you stop at a traffic light. A throttle body that has not been cleaned properly can cause interruptions in the airflow. This also leads to unbalanced idle speed.

Throttle Body Replacement Cost

The throttle body might be an extremely important part of a car. Although it is not the most expensive component of your vehicle. Even though it is not very expensive but it is not exactly cheap either. To put in easier words, if your vehicle is in need of a new throttle body, you can expect to spend anywhere between $450 to $600 for both the parts and labor.

People who want to do this as a DIY project might also not save up a huge amount as the parts alone cause a lot. If you do decide to do this job yourself, you can still expect to spend somewhere $400 to $500 for a new throttle body. A DIY repair could certainly help with the throttle body replacement cost.

As the replacement cost for a throttle body is more on the expensive side, it is a good idea to try and clean up your existing throttle body. This might help you save a few bucks.  If you experience any of the dirty throttle body symptoms listed above, you need to start working on your car.

Throttle Body Facts:

  1. The throttle body controls the flow of air into the engine in modern fuel-injected cars.
  2. Proper synchronization between the throttle body, fuel intake, and the accelerator pedal is essential for optimal engine performance.
  3. Dirt or malfunctioning of the throttle body can cause issues with engine performance and unburned fuel passing through the exhaust system.
  4. Symptoms of a dirty throttle body include grime build-up, poor fuel economy, poor or high idle, uneven or slow acceleration, electrical problems, airflow disruptions, and the check engine light illuminating.
  5. Grime build-up and carbon deposits are the main causes of a clogged throttle body.
  6. A clogged throttle body can impact fuel economy, idle speed, and acceleration.
  7. Dirty throttle body sensors can result in faulty or unnecessary corrections to the air-fuel mixture, causing the car to go into a secondary power-reduced mode.
  8. Cleaning the throttle body is the first step to resolving issues, but if it’s electronically controlled, it’s better to get a certified mechanic to inspect it.
  9. Mechanical systems can be cleaned by the car owner, but it’s essential to check the owner’s manual before starting the cleaning process.
  10. If cleaning doesn’t work, a new or used replacement throttle body may be necessary.


A throttle body is one of the most important parts of your intake system. A malfunctioning throttle body can be a barrier in the way to your car performing at its optimum condition. So if your car is facing any dirty throttle body symptoms, you need to show your car to a mechanic. A clogged throttle body is not only bad for the health of your car, but it also puts your safety at risk.

Frequently Asked Questions

There are several questions regarding the dirty throttle body symptoms. That is why we are here to help you know the answer to some of them. Here is a list of some of the most popular and common questions people have…

What Is A Throttle Body

The throttle body is one of the most important pieces present in an engine. It is a part of your vehicle’s intake system that is responsible for controlling the air flowing into your engine. It only allows a certain amount of air to maintain the perfect air-fuel ratio for perfect performance. The throttle body is usually placed between the air intake and the engine manifold. This allows the device to pull fresh air into the combustion process.

How To Clean Throttle Body

There is a proper way of cleaning your throttle body. The throttle body is an important and delicate part of the fuel system. That is why it needs to be cleaned with caution and care. There are several products that are available in the market that will help you do that. WD-40 is the safest product you can use on your throttle body. Remember, while working on your throttle body make sure to disconnect the electrical components as well as the air filter.

How Much Is A Throttle Body

A throttle body might not be the most expensive part of your car, but it is not cheap to fix or replace. A throttle body is extremely important for the smooth and optimum functioning of your vehicle. Hence you need to get your car fixed as soon as possible. Cleaning your throttle body can cost about $400 to $500, and replacing the whole throttle unit costs around $1000 to $1500.

What Are The Symptoms Of A Dirty Throttle Body

A dirty throttle body is easy to diagnose as it comes with several features. Some of these symptoms are lack of power, check engine light turning on, rough idle, issues with acceleration, and poor gas mileage. If your car is facing any of these problems, your car is facing a malfunctioning throttle body.

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