Symptoms of a Bad or Failing Throttle Body

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Cost of Replacing a Bad or Failing Throttle Body

Common signs include dirt, grime, and carbon deposits on the inside of the housing, electrical problems, vacuum leaks, and a very poor or high idle. Our certified technicians can come to you and diagnose the problem. You will receive a $30 credit towards any follow-up repairs that result from the diagnostic. Following are example prices for Throttle Body Replacement. Click on the button below to get an upfront quote for your car.

Cars Estimate Parts Cost Labor Cost Savings Average Dealer Price
2011 GMC Yukon $443 $372.69 $70.00 7% $480.19
2014 Kia Optima $432 $362.38 $70.00 7% $469.88
2012 Chevrolet Express 2500 $338 $268.13 $70.00 9% $375.63
2013 Audi A4 Quattro $683 $584.81 $98.00 7% $735.31
2004 Lexus ES330 $473 $375.20 $98.00 9% $525.70
2006 Porsche Cayenne $461 $390.66 $70.00 7% $498.16
GET A QUOTE FOR YOUR CAR Get a fair and transparent estimate upfront

How to Diagnose a Bad or Failing Throttle Body?

throttle body

In today’s modern fuel injected cars, the throttle body is a critical piece of the air intake system that controls the amount of air flowing into the engine. The amount of air allowed in is a function of how far the driver presses the accelerator pedal to the floor. As you press down on the pedal, a sensor called a throttle position sensor receives a signal relative to where your foot is, ranging from all the way up (zero acceleration), to all the way down (full acceleration). This sensor relays this information to the car’s main computer giving it constant updates as to the position of the throttle. The position of the pedal along this range is how the computer knows what to tell the fuel injection system in terms of how much more or less fuel to inject into the system.

When this process is regulated properly, a perfect balance of air and fuel is introduced to your car’s engine, allowing it to run smoothly and perform at an optimum level. There are a number of reasons that a throttle body may fail to work properly.

1. Dirt, grime, and carbon deposits on the inside of the housing

Dirt and grime can build up inside the housing, causing interruption in air/fuel flow. As a result of not having an ordinarily smooth surface for the fuel and air to flow through, this delicate mixture is interrupted with a rough surface which causes an imbalance in flow. Similar to dirt and grime, carbon deposits can create an uneven surface inside the walls of the throttle body which can disrupt the atomization of the air/fuel mixture.

2. Electrical problems

Electrical connection problems can cause inaccurate or intermittent information to be relayed to the car’s computer. As with any electrical connection, connectivity issues can cause a wide variety of unpredictable signals to be transmitted. In the case of the throttle body (and related sensor), when this happens it causes inaccurate or intermittent information to be relayed to the car’s computer, resulting in faulty corrections to the air/fuel mixture.

3. Vacuum leaks or an incorrectly adjusted throttle stop

Vacuum leaks can disrupt the air/fuel flow due to an imbalance of air flow which can cause throttle body pressure problems. The issue could also be an incorrectly adjusted throttle stop. This is a component that acts as a gate-keeper and establishes a minimum or maximum position for a throttle body plate to be opened or closed.

4. Poor or high idle

When a throttle body is not functioning correctly, some noticeable characteristics may be poor or very low idle. This can include stalling when coming to a stop or very low idle after starting, or even stalling if the throttle is quickly pressed (resulting in the throttle body plate opening and closing very quickly).

In the case of a vacuum leak, you may experience a very high idle, which is caused by too much air being allowed into the intake system. This typically is caused by a fairly large vacuum leak. All of these symptoms will contribute to poor engine performance and as a result will cause your check engine light to come on.

As a part of your regular service intervals, include the air induction service and fuel injection flush which cleans out any carbon deposits and dirt. You will need to have the Check Engine Light shut off by a qualified mechanic, such as one from [YourMechanic]. This will include scanning your car’s computer system for fault codes, which will likely indicate problems with your fuel injection system, and specifically throttle body components. These will give the mechanic an indicator as to what to check for and how to repair the problems.


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YourMechanic Throttle Body Replacement Service

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13 years of experience
174 reviews
13 years of experience
Pete was awesome! He was very thorough & done the job in no time! He took the time to answer all questions I had! Very easy going guy who truly knows what he's talking about! I even learned things that I didn't know before. I highly recommend him to anyone! Will be booking him again! This was my first time going through YourMechanic & it was great!


38 years of experience
883 reviews
38 years of experience
Ben showed up on time and gave me a quick call so I could get him in our gate. He was an absolutely amazing personality and mechanic. He had the old part out and the new part on the vehicle in under 20 minutes. The computer resetting took longer than the installation! The car is running well and cannot find any problems with the service at all. Although I have used a house-call-car-doctor previously in another city, and find the costs of overhead gone and the convenience amazing, the parts and service guarantee from this company were the tipping points on my decision to go with YourMechanic.


30 years of experience
363 reviews
30 years of experience
Always on time, friendly and knows what he is doing! This is the 4th time we've have Matthew work on one of our cars. I have recommended him to a friend and know that they feel the same way!


31 years of experience
85 reviews
31 years of experience
Very satisfied with the work done and friendly personality

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