Common Problems After Cleaning the Throttle Body

A high idle is one of the most common problems after cleaning the throttle body, but resetting the ECU could correct the issue.
Written by John Davis
While it’s usually a straightforward job, cleaning your car’s throttle body can result in some problems if you make any mistakes. The most common issues car owners experience after cleaning the throttle body are a high idle and the check engine light turning on.
  • Your car’s throttle body is a small but essential piece of the vehicle’s air intake system, and it’s one of the most critical components of your vehicle to maintain.
  • Cleaning the throttle body shouldn't cause problems—but if it’s done incorrectly, it can result in electrical problems and high idling. 
  • Resetting your car’s ECU after cleaning the throttle body can reduce the chances of problems arising.

The purpose of your car’s throttle body

The throttle body is the part of your car’s air intake system that controls the airflow to the engine. It is connected to the gas pedal between the air filter and the intake manifold. 
The mass airflow sensor (MAF sensor) is usually attached to the throttle body, and relays information about the air quality, temperature, and density to the car’s electronic control unit (ECU). 
The throttle body contains a butterfly valve known as a “throttle plate” which opens in response to the driver’s input on the accelerator pedal. When the driver presses down on the pedal, the control valve inside the throttle body opens, allowing more air into the engine. 
Often, a
throttle position sensor
(or TPS) is attached to the throttle body to help relay information to the ECU about the valve’s position. This data tells your car’s ECU whether you’re idling, pressing the pedal to the floor, or hovering somewhere between the two. 

The signs of a dirty throttle body

The throttle body is a vital component of your vehicle’s air intake system—and a dirty throttle body can lead to problems with your car’s engine performance. 
These are some of the most common symptoms of a dirty throttle body:
  • Grime buildup:
    One of the most common signs of a dirty throttle body is dirt or grime buildup. This inhibits the amount of air that can get to your engine, reducing your accelerating power. Carbon deposits may form inside the throttle body and cause similar issues.
  • Poor fuel economy:
    A clogged or dirty throttle body can cause your car’s fuel economy to plummet. If you notice your mileage dropping by 10-15%, you might have a clogged throttle body.
  • A check engine light:
    A bad throttle body can alert the vehicle’s electronic throttle control, which will turn on your car’s
    check engine light
    . Problems with the throttle body sensor can also result in check engine codes, like P0121. 
  • Rough engine idle:
    An irregular or jerky idle speed is one of the most common signs of a clogged or dirty throttle body. This happens when uneven airflow causes the engine’s idle to fluctuate. 
  • Vehicle stalling:
    If your car stalls after coming to a stop or when pressing on the gas pedal, you might have a dirty or clogged throttle body. Similar to a rough idle, this happens because of inconsistent airflow entering the engine.
  • Slow or jerky acceleration:
    If your car’s engine isn’t receiving good quality air or the right air/fuel mixture, you may have issues accelerating. This means your vehicle is effectively choking and needs more airflow to perform well.
  • Engine misfires:
    An incorrect air/fuel mixture caused by a dirty throttle body commonly results in engine misfires. This can feel and sound like a small bump or ping when revving your engine. 

Choosing the right throttle body cleaner

Car enthusiasts and DIY-ers are typically able to handle cleaning the throttle body without professional help—but before you can start, you’ll need to purchase the correct type of cleaner. 
Using the incorrect chemical on your car’s throttle body can damage components and result in even more problems than just some dirt or a clog.
While throttle body cleaners and carb cleaners are often used interchangeably, you should avoid using regular carburetor cleaners on your throttle body. Note, however, that some throttle body cleaners are multipurpose and have “carb cleaner” in their names. 
Look for these cleaners at your local auto parts store or online:

How to clean the throttle body without taking it off

While you can completely remove the throttle body for cleaning, performing this service with the part still attached to the car is possible. If you’re not comfortable tackling a throttle body cleaning on your own, your local repair shop or dealership should be able to perform this service for you. 
It’s a relatively simple process and shouldn’t require many more tools aside from a socket set, a flathead screwdriver, a clean rag or toothbrush, and a helper. If you’ve got those in your garage, you’re ready to get started: 
  • Step 1:
    Open the hood and locate the air intake system. Then, follow the air tube from the air filter to find the throttle body. 
  • Step 2:
    Disconnect the air tube from the throttle body. You will need to loosen the hose clamps to do this, and you may also need to remove the air box and filter.
  • Step 3:
    Clean the throttle body. Have your helper turn on the engine and lightly press the gas pedal to open the butterfly valve while you spray your cleaner inside the throttle body several times. Then, wipe the inside of the throttle body with your clean rag or a toothbrush. Be careful not to touch the inside of the throttle body with your fingers unless you are wearing gloves, as the oil from your skin can cause dirt to stick to the component. 
  • Step 4:
    Turn off the engine and reassemble the air intake system. 
  • Step 5:
    Wait 5-10 minutes, then start your car. You may notice some smoke coming from your exhaust, especially if you used Sea Foam to perform a top-end clean. The best way to clear this smoke is to drive your car a few miles until the exhaust is clear. 
Key Takeaway
To clean your throttle body without removing it, disconnect the air tube, spray several squirts of your cleaner into the throttle body while your helper presses the gas pedal, then use a rag or toothbrush to wipe out the inside of the component. 

Why cleaning the throttle body is important

Cleaning the throttle body removes dirt, grime, and carbon buildup from the component. It’s an important service that you should perform every 60-75,000 miles to keep your engine running smoothly. 

Resetting the ECU after cleaning the throttle body

Resetting the ECU after cleaning the throttle body is always smart, as doing so will reduce the chances of problems after clearing the throttle body, like a high idle. Luckily, it’s a simple process that takes only a few minutes: 
  • Step 1:
    After you finish cleaning your throttle body, start the car and let it idle for four minutes. The RPMs might be high at first but should gradually settle down as the ECU absorbs the data.
  • Step 2:
    Turn off the car for 90 seconds. Then, turn it back on and allow it to idle for another four minutes. 
The engine should idle like normal after you complete these steps. If there is still a high or uneven idle, there is a problem beyond the ECU.

How to fix high idle problems after throttle body cleaning

Some of the additional problems that can cause a high idle after cleaning your throttle body include:
  • A vacuum leak:
    A vacuum leak occurs when the throttle body allows more air into the engine than necessary, resulting in a too lean situation. If this happens, your first step should be to check the vacuum hose for leaks and replace or repair it if necessary.
  • A torn intake hose:
    It’s possible to damage the intake hoses when cleaning the throttle body. If you tear one of these hoses, you might experience a high idle. To fix this issue, simply replace or repair the hose.
  • Electrical problems:
    You can often diagnose and fix electrical issues with the throttle body by using an OBDII scan tool. However, some electrical problems may be complex and require the attention of an expert.
  • Leftover grim in the throttle body:
    You might experience a high idle if you did not thoroughly clean the throttle body. You can fix the issue by cleaning the part again. If the throttle body is especially dirty, you may need to remove it from the vehicle for deep cleaning. 

Does cleaning a throttle body damage it?

Properly cleaning the throttle body should not damage it. However, if you mishandle any parts or don’t sufficiently clean the component, you can cause damage to the throttle body, such as vacuum leaks, torn intake hoses, and leftover grime or carbon buildup.
 “Super cheap!
saved me over $4500 during the entire year. The money really adds up.” —D’Shawn G.


Easiest way to compare and buy car insurance

No long forms
No spam or unwanted phone calls
Quotes from top insurance companies
Find insurance savings — it's 100% free